Cytotoxic agents active against mucinous adenocarcinoma of the ovary

OBJECTIVE: To determine the stability of immunoglobulin E levels in obstetric sera. METHODS: AlaSTAT(R) and AlaTOP(R) (Diagnostic Products) were used to assay total and specific IgE levels in obstetric sera collected in Memphis, TN and Portland, OR. The samples were collected from the Collaborative Perinatal Project (CPP) between 1959 and 1965 and stored at -20 degrees C. The assay results were compared with IgE levels found in sera collected at the same locations for the Calcium for Pre-eclampsia Prevention Study (CPEP) and stored since 1992 at -70 degrees C. The samples were also assayed for cockroach (CR) and mouse urine specific IgE using the AlaSTAT(R) assay (Diagnostic Products). RESULTS: Total IgE and specific IgE to CR and mouse urine were detectable in older and recent samples. The median total IgE for the recent and older Portland samples was 26 IU/ml and 65 IU/ml, respectively. The median total IgE was identical (40 IU/ml) in the recent and older Memphis samples. CONCLUSION: Long-term storage does not diminish the ability to measure serum IgE. Levels of IgE in sera stored 32-37 years were equal to or greater than levels in sera stored for 5 years. reserved.     

Prognostic evaluation of cardiogenic shock by the severity

The aim of this study was to assess the total IgE levels in the supernatants and cellular components of colostrum from atopic and nonatopic mothers. Immunoglobulin E protein was detected in 34/39 milk samples, with a median level of 0.3 microgram/l. In 13 mothers, IgE protein was also detected in the cellular fraction of colostrum, with a median level of 0.13 microgram/l. Of the total IgE content in breast milk, 5-12% was transported intracellularly. The total IgE antibody levels were similar in both milk supernatants and cells from atopic and nonatopic mothers. There was a strong relationship between total IgE antibody levels in serum and in breast milk (r = 1.0, P < 0.001), suggesting that IgE antibodies were passively transported from blood into breast milk. The levels of total IgE in human milk are probably too low to have a significant effect on the regulation of the IgE antibody levels in the neonate.     

The relative paucity of IgE in human milk

The levels of IgE were determined in paired samples of serum and milk when whey obtained 3 to 8 days of postpartum, from 16 human lactating mothers who had reported a history of allergy to a variety of common allergens. Two assay procedures were employed to measure total IgE, a double-antibody assay and a commercially available solid phase assay (RIST). In addition, each sample of serum and whey was tested for specific IgE antibodies to a variety of allergens by the RAST test. The levels of total serum IgE were between 30 and 2300 I.U./ml and relatively good agreement was observed for both the double-antibody and RIST methods. In contrast, total IgE levels in milk whey were either undetectable (less than 3.0 I.U./ml in 14 of 16 subjects) or very low when analyzed by the double-antibody method, but were very high (400 to 1650 I.U./ml when analyzed by the RIST method. However, IgE added to milk whey could be measured by the double-antibody procedure indicating that the low levels detected in milk were not a fault of the double-antibody assay. It was assumed that the RIST test was subject to nonspecific interference by factors in milk whey which caused the determination of high, but incorrect, levels of IgE. Specific IgE antibodies were detected in the serum of 10 of 16 subjects but were not present in milk whey. A comparison of the whey/serum ratios of albumin, IgA, and IgE suggested that little, if any, IgE is selectively synthesized or secreted in the mammary gland.     

Distribution of a stable isotope of chromium (53Cr) in serum, urine, and breast milk in lactating women

To determine the fate and distribution of chromium during lactation, six lactating women (25-38 y old) were given three doses of the tracer 53Cr (7.55 micromol/d, or 400 microg/d) on days 1, 2, and 3 of the study. Diet records, blood samples taken while subjects were fasting, and 24-h composite milk and urine samples were collected from day 0 to day 6. Fasting blood samples, morning milk samples, and 24-h urine samples were also collected on days 8, 10, 15, 30, 60, and 90. 53Cr and natural and total chromium concentrations in biological fluids were measured with gas chromatography-mass spectrometry and total urinary chromium was measured with atomic-absorption spectrometry. 53Cr was detectable in serum 2 h after dosing and continued to be detected from day 30 to day 60. Changes in total serum chromium concentration in response to the oral dose suggested that chromium concentrations in blood were not tightly regulated. 53Cr was not detected in breast milk and no significant changes in natural chromium concentration in milk were observed in response to the oral doses, suggesting that breast-milk chromium concentrations are independent of intake. The estimated chromium intake of exclusively breast-fed infants was 2.5 nmol/d (0.13 microg/d), below the lower end of the range of estimated safe and adequate daily dietary intakes (10-40 microg/d) for infants 0-6 mo of age. The baseline chromium concentration in urine and the minimum 53Cr absorption in lactating women were comparable with values for nonpregnant, nonlactating subjects. Chromium losses in breast milk do not appear to be compensated for via increased absorption or decreased excretion.     

Immunoglobulin A levels in southern elephant seal (Mirounga leonina) milk during the suckling period

Immunoglobulin A (IgA) levels in milk samples from southern elephant seals at King George Island, Antarctica are reported. IgA levels were determined throughout the suckling period (approximately 23 days). The IgA concentration in southern elephant seal milk was lower than in other mammals and, unlike most mammalian milk, was not high during early lactation. There was not a definite pattern in IgA levels, which fluctuated within narrow limits throughout the suckling period (mean +/- SD, 30.81 +/- 6.38 mg IgA/100 g milk). If IgG was present, its level was too low to be detected by the method used. This is the first evidence in Southern elephant seal of the possibility of transmission of passive immunity after birth involving secretion of IgA in the milk.     

Spontaneous IgE production in asthmatic children

In this study, we demonstrated spontaneous IgE production by peripheral blood mononuclear cells of asthmatic children. In 26 asthmatic children, the level of spontaneous IgE ranged 0.1-15.0 IU/ml and in 5 healthy normal children showed under 0.051 IU/ml. In 5 of asthmatic children, specific antibody of Dermatophagoides farinae was detected from PBMC by CAP RAST. In healthy normal children, specific antibody of Df was not detected. Spontaneous IgE production by PBMC and serum IgE level showed well correlation (gamma = 0.835, p < 0.001). Spontaneous IgE production and specific antibody of Df by PBMC also showed well correlation (gamma = 0.717, p < 0.001) IgE production of asthmatic children was inhibited by IFN-gamma.     

Toward optimal health: the experts respond to hair loss in women. Interview by Jodi Godfrey Meisler

Lactose intolerance is a common adverse reaction to milk in adults, while milk hypersensitivity is a disorder of infancy. We hypothesized that milk hypersensitivity may cause many unspecific gastrointestinal disorders in adults. Twenty adults were subjected to double-blind, placebo-controlled milk challenge. Phagocyte activity, and Fc gamma and complement receptor expression of phagocytes were assayed, and serum total IgE, milk-specific IgE, and serum reactivity to milk protein were determined. The challenge increased phagocyte activity and complement receptor expression of phagocytes in subjects designated milk-hypersensitive, who had gastrointestinal symptoms from milk ingestion but normal lactose tolerance. The increase was not detected in lactose-intolerant or control subjects. The milk-hypersensitive group was also distinguished from the lactose-intolerant group by enhanced serum reactivity to milk protein. Only two out of nine milk-hypersensitive subjects had detectable milk-specific serum IgE. It is concluded that milk hypersensitivity in adults, occurring as gastrointestinal reactions, may be more common than previously thought.     

The development of atopic sensitization in Estonian infants

In a prospective study, 251 infants were followed from birth up to 12 months of age, recording manifestations of allergy by questionnaires at 3, 6, 9 and 12 months and by clinical examinations at 6 and/or 12 months. Blood samples were obtained at birth and at 6 and 12 months and analysed for serum IgE levels. The children were skin-prick tested with foods at 6 and 12 months of age and with inhalant allergens at 12 months. Blood samples from SPT-positive individuals and controls were analysed for the presence of IgE antibodies to common inhalant allergens and their cord sera for the presence of IgE antibodies to cow's milk and egg. Twelve infants (7%) were sensitized against foods [3 to cow's milk (CM) and 9 to egg white (EW)] at 6 months and 11 (5%) (2 to CM and 9 to EW) at 12 months. Seventeen infants (7%) had IgE antibodies against inhalant allergens at 6 and/or 12 months, as determined by either SPT and/or the demonstration of circulating IgE antibodies. Out of 30 children with positive SPT and/or circulating IgE antibodies against foods and inhalant allergens at any age, 6 had atopic dermatitis, 4 gastrointestinal food allergy, 1 urticaria and 4 probable allergy, while 15 had no clinical manifestation of allergy. Immunoglobulin E antibodies against Ascaris were detected in 17% of the infants with S-IgE levels > 20 kU/l. The study indicates that the incidence of sensitization and manifestations of allergic disease is similar among Estonian and Scandinavian infants during the first year of life. Given earlier findings indicating a significantly higher prevalence of atopic disease in Scandinavian school-children relative to their counterparts in Eastern Europe, the present study suggests that the key events which determine disease expression do not occur exclusively during the first year of life.     

The Canadian Cardiovascular Society--the first and the next 50 years

BACKGROUND: Although beta2-adrenoceptor agonists are widely used in the treatment of asthma, a number of studies have suggested that their long-term use may exacerbate the condition. One possible mechanism for this stems from the in vitro observation that beta2-agonists increase IgE synthesis by human blood mononuclear cells. OBJECTIVE: We sought to examine the effect of regular beta2-agonist therapy on IgE production in vivo in human volunteers. METHODS: Placebo or salbutamol (8 mg BD) tablets were given in a double-blind, randomized fashion to 25 volunteers allergic to grass pollen throughout a period encompassing the UK grass pollen season (April through September). Levels of serum IgE were measured monthly, and nasal IgE was measured at the height and end of the season. Efficacy was assessed through monthly recordings of symptoms of blocked nose (vascular) and other symptoms of rhinitis (nonvascular). RESULTS: For the whole group the geometric mean of serum IgE levels rose from a baseline of 58.7 IU/mL (range, 0 to 1027 IU/mL) to 140 IU/mL (range, 12 to 878 IU/mL) at the height of the pollen season (P =.0001). There was no significant difference between the magnitude of the rise in IgE between the groups with a ratio of increase for salbutamol/placebo of 1.17 (confidence interval = 0.78 to 1.75). There was no change in nasal IgE levels. Total and nonvascular symptom scores were reduced by salbutamol, reaching statistical significance at the height of the pollen season (P <.05). CONCLUSION: An oral dose of the beta2-agonist salbutamol, sufficient to maintain therapeutic levels and provide clinical benefit, does not accentuate the seasonal increase of IgE in human atopic volunteers.     

Risk factors for sensitisation to methyltetrahydrophthalic anhydride

OBJECTIVES: To examine an association between specific IgE to methyltetrahydrophthalic anhydride (MTHPA) and exposure time, atopic history, smoking habits, and total IgE concentrations. METHODS: A cross sectional survey was carried out on a population of 148 workers from two condenser plants using epoxy resin with MTHPA, an acid anhydride curing agent known to cause allergy. RESULTS: Using a Pharmacia CAP system with a MTHPA human serum albumin conjugate, specific IgE antibody was detected in serum from 97 (66%) out of the 148 workers exposed to MTHPA. Stepwise multiple linear regression analysis showed a striking relation between log concentrations of specific and total IgE (P < 0.0001). Furthermore, when the workers were divided into two groups according to a cut-off point (100 IU/ml) between low and high total IgE, current smoking was significantly (P = 0.025) associated with specific IgE production only in the group with low total IgE (< 100 IU/ml). CONCLUSIONS: Smoking is the most significant risk factor for raising specific IgE to MTHPA in the group with low total IgE concentrations.     

IgE-induced passive sensitization of human isolated bronchi and lung mast cells

Passive sensitization of human isolated lung with serum from atopic asthmatic patients provides an opportunity to study the link between airway hyper-responsiveness and the allergic process. To directly demonstrate the role of immunoglobulin E (IgE) in the effect of the atopic serum, we have compared the effect of passively sensitizing both human bronchi and isolated lung mast cells with either serum from atopic asthmatic patients or human monoclonal IgE. Peripheral bronchi ( < 5 mm in internal diameter) were dissected out from human lung obtained at thoractomy and isometric contraction was studied in response to a variety of immunological stimuli according to the sensitization protocol. Mast cells were also isolated from human lung and histamine release was measured under similar experimental conditions. A contractile response was elicited by either the specific antigen or anti-IgE (0.6-600 ng.mL-1) but not anti-immunoglobulin G (IgG) 0.2-20 micrograms.mL-1) in airways sensitized with atopic serum (total IgE concentration of approximately 1,000 international units (IU).mL-1). The maximal contractile response to anti-IgE was 75 +/- 22% of the response to 1 mM acetylcholine. Similarly, anti-IgE released histamine from isolated lung mast cells sensitized with atopic serum up to 22.4 +/- 2% of total histamine measured within mast cells. When isolated airways or mast cells were sensitized with human monoclonal IgE (1,000 IU.mL-1), response to anti-IgE in terms of contractile response or histamine release, respectively, were not significantly different from those obtained following passive sensitization with atopic serum. Finally, the bronchial contractile response to anti-IgE depended not only on the concentration of anti-IgE but also on that of IgE (300-2,000 IU.mL-1) used to sensitize the airways. These results indicate that the effect of antigen or anti-IgE in peripheral bronchi passively sensitized with atopic serum is mimicked when sensitization is carried out directly with human monoclonal IgE.     

IgE antibody during infection with the ovine abomasal nematode, Teladorsagia circumcincta: primary and secondary responses in serum and gastric lymph of sheep

A monoclonal antibody to ovine IgE was employed in an ELISA to investigate the IgE antibody responses in serum and gastric lymph to a primary infection of Teladorsagia circumcincta, and following challenge in previously infected sheep. During a primary response, IgE antibody to antigens derived from the infective third stage (L3) and adult (L5) worms were negligible, with low levels of IgE antibody detected in serum and lymph. In contrast, there was a pronounced IgE antibody response in 2/4 sheep to L3 antigens during 2-8 days after challenge of previously infected animals but low levels of IgE antibody to L5 antigens. This response was confirmed in a second but similar experiment, where relatively high levels of IgE antibody was detected to antigens from L3. Antibody levels were higher in lymph than in serum from the same animals, and Western blots of L3 antigen following SDS-PAGE under reducing conditions revealed several bands of MW26-96KD which reacted with the IgE antibody from gastric lymph. Immunohistochemical staining indicated that these IgE antibodies may be reacting with allergens associated with the surface cuticle of the worms.     

Microsatellite analysis and telomerase activity in archived tissue and urine samples of bladder cancer patients

We performed microsatellite analysis and tested telomerase activity in paired tissue and urine of bladder cancer patients from frozen archived samples. DNA obtained from microdissected tumor and urine sediment was analyzed and compared to peripheral lymphocytes for microsatellite alterations (loss of heterozygosity [LOH] or instability) using a panel of 20 microsatellite markers in 15 patients with transitional or squamous cell carcinoma of the urinary tract. Additionally, telomerase activity was determined in 12 microdissected tumor specimens and corresponding frozen urine pellets. Tumor cell DNA was detected by microsatellite analysis (LOH or shift) in at least one marker in 14/15 microdissected tumor specimens and in 13/15 DNA samples obtained from urine sediments. Telomerase activity was present in 11/12 tumor samples but could not be detected in any of the corresponding urine sediments. Frozen archived urine samples are useful for retrospective studies utilizing microsatellite analysis or other PCR-based approaches after DNA extraction. However, the evaluation of telomerase protein activity in stored urine samples appears to be unsuitable.     

Functional gastrointestinal disorders: psychological, social, and somatic features

BACKGROUND: Helminthic infections induce an IL-4-dependent polyclonal stimulation of IgE synthetization. It is still unclear, however, what role helminths play in allergic sensitization. OBJECTIVE: We sought to determine the relationship between Ascaris-specific IgE and allergic sensitization in a nontropical country. METHODS: In 2 consecutive cross-sectional surveys in 1992-1993 and 1995-1996, data from school entrants (age range, 5 to 7 years), third graders (age range, 8 to 10 years), and sixth graders (age range, 11 to 14 years) were collected. The 2 younger groups were reexamined in the second survey. Data for about 2300 children, including a cohort of 700 subjects, were analyzed. Ascaris IgE and total and specific IgE to inhalant allergens were measured, and skin prick tests were performed. Information about asthma and allergic rhinitis was collected by a questionnaire. RESULTS: Children who were Ascaris-IgE seropositive (>0.35 IU/mL) in both surveys had 10-fold higher levels of total IgE (451 IU/mL vs 45 IU/mL, P < .001) and higher prevalence rates of allergen-specific IgE seropositivity (56.3% vs 26.6%, P < .001). They also had a higher prevalence of allergic rhinitis (12.6% vs 3.7%, P < .001) and asthma (5.7% vs 1.6%, P < .05). In subjects who were Ascaris-seronegative in the first survey but seropositive in the second survey, total and specific IgE increased markedly. Sensitization to Dermatophagoides pteronyssinus increased nearly 3-fold in this group. In contrast, in children who became Ascaris-seronegative, total and specific IgE decreased. CONCLUSIONS: Contact with low doses of helminthic antigen is associated with an increase of total and specific IgE production. Helminthic infections in East German children are not the cause for a low prevalence of allergies in the former East Germany.     

Immunoprocedures for detecting human chorionic gonadotropin: clinical aspects and doping control

The pregnancy hormone human chorionic gonadotropin (hCG) is also present at low concentrations in plasma and urine of men and nonpregnant women. hCG immunoreactivity occurs in various molecular forms: Besides the intact hCG heterodimer, considerable amounts of proteolytically cleaved forms, free subunits, and fragments are found in plasma and urine. Especially in urine, proteolytic fragments constitute a major part of the hCG immunoreactivity. The different forms of hCG cross-react to various degrees in immunoassays and constitute a problem for standardization of specific hCG determinations. After injection of hCG (10,000 IU of Pregnyl; Organon), above-normal concentrations of hCG can be detected in serum and urine for 7-11 days. Most immunoassays for hCG also measure hCG beta. Quantitative hCG determinations are mainly performed on serum samples, and very few commercial hCG determinations have been validated for determination of urine samples. Considerable care must therefore be exercised when utilizing such assays to analyze urines for doping control.     

Presence of high levels of non-degraded gliadin in breast milk from healthy mothers

BACKGROUND: Secretion of dietary antigens into breast milk has been extensively documented. The presence of these antigens is of relevance because they could be involved in the modulation of the immune response in neonates. The objective of this study is to determine the gliadin concentration in milk, colostrum, and serum samples from healthy lactating mothers on a normal diet. Gliadin levels in milk samples from a group of six mothers after a brief period of gluten restriction were also determined. The molecular weight of secreted gliadins was also analysed. METHODS: Gliadin concentration was determined with a highly sensitive competitive enzyme-linked immunosorbent assay, modified so as to eliminate anti-gliadin antibody interference. The level of gliadin/IgA anti-gliadin immune complexes in milk, colostrum, and serum samples was determined. RESULTS: Gliadin was detected in all 49 milk samples. Its concentration varied between 5 and 1200 ng/ml (mean, 178 ng/ml). In colostrum (n = 14) gliadin levels were higher (range, 28-9000 ng/ml; mean, 883 ng/ml), not being detectable in one case. Gliadin was detectable in 14 of 31 serum samples, in which levels were lower than in milk and colostrum samples (mean, 41 ng/ml). Neither a correlation between gliadin levels in milk, colostrum, and serum samples from the same subject nor a relation between gluten intake and gliadin concentration in milk samples from six subjects under a 3-day gluten-free diet could be found. Higher levels of immune complexes were observed in colostrum samples than in milk and serum samples. No correlation was detected between gliadin concentration and the level of immune complexes. The analysis of milk and colostrum samples by immunoblotting showed bands of immunoreactive gliadin presenting Mr similar to those of native proteins from wheat extracts. CONCLUSIONS: Very high levels of gliadin were detected in milk samples from healthy mothers on an unrestricted diet. Gliadin levels were higher than those reported for dietary antigens in other studies. Breast milk contained non-degraded gliadins and gliadin/anti-gliadin IgA immune complexes.     

Natural history of cows' milk allergy in children: immunological outcome over 2 years

In this investigation 98 children (median age 24 months) with cows' milk allergy (CMA) were studied over a median period of 2 years to see whether acquisition of clinical tolerance to cows' milk was associated with the changes in levels of IgG and IgE anti-cows' milk antibodies, and skin test reactivity to a cows' milk extract. Two groups of CMA patients were examined. The first were IgE sensitized and responded rapidly to small volumes of cows' milk with urticaria, and/or exacerbations of eczema, and/or wheeze, and/or vomiting (n = 69). The second, a late reacting group (n = 29) demonstrated coughing, diarrhoea, eczematoid rashes, and/or a combination of these which developed more than 20 hr after commencing normal volumes of cows' milk. Significant immunological changes were confined to the 69 IgE sensitized immediate-reacting-group of patients. Of these, there were 15 children who achieved clinical tolerance to cows' milk and they showed a significant fall in the levels of skin test reactivity to cows' milk over the study period (P < 0.01). In addition, these 15 children had lower serum IgE antibodies to cows' milk proteins both at the outset and the final follow-up compared with the 54 patients whose CMA persisted. No consistent change in the IgG antibody responses to cows' milk proteins was seen in either group of patients over the study period. The findings suggest patients with immediate type hypersensitivity to cows' milk proteins whose disease persists for more than 2 years have a more severe dysregulation of IgE synthesis to cows' milk proteins from the outset.(ABSTRACT TRUNCATED AT 250 WORDS)     

Levels of organochlorine pesticides residues in milk of urban mothers in Kenya

Organochlorine compounds (OCPs) are toxic products capable of producing serious adverse health consequences. When used to control pests, certain OCPs persist in the environment and accumulate in the fatty tissues of living organisms, reaching higher levels in animals higher in the food chain. Many countries have therefore either restricted or banned the use of OCPs. DDT used to be widely used in Kenya to control pests, but is now used only to control mosquito populations. The contamination of human milk by organochlorine and other related compounds is a major concern in many parts of the world. Findings are reported from a study conducted to assess the levels of OCPs in an urban area of Kenya and to compare OCP levels in human milk from a previous study in rural areas of the country. 216 milk samples were collected from mothers aged 18-30 years in hospital maternity wards or attending postnatal clinics in selected areas in Nairobi in 1991. All mothers involved in the study were nursing either their first or second child, and had lived in Nairobi for at least 5 years before the date of sampling. Samples were collected from mothers who were up to 4 weeks postpartum and analyzed for the presence of OCP residues. 9 OCPs were detected, with p,p'DDT and p,p'DDE being the most frequently encountered contaminants in all samples analyzed. p,p'DDE was detected in 99.5% and p,p'DDT in 78.2% of all samples. Other residues detected were dieldrin (27%), beta-HCH (18.5%), lindane (12%), and alpha-HCH (8.8%). Levels of sum DDT ranged from 0.004 to 6.321 mg/kg fat. Mothers living in Nairobi have low levels of OCPs in their breast milk compared to mothers in rural areas. The relatively lower urban levels could be attributed to the restricted use of OCPs. People need to be taught how to safely use pesticides.     

Day-case adenoidectomy--is it safe?

In a prospective study we looked for the presence of both IgE plasma cells in small bowel mucosa and specific serum IgE antibodies to cow milk in children suspected of cow milk protein intolerance. Thirty-one children with complaints possibly due to cow milk intolerance were submitted to two consecutive cow milk elimination/challenge tests. The diagnosis of cow milk protein intolerance was confirmed in 16 of our 31 patients on the basis of two positive elimination/challenge tests. IgE plasma cells were found in nine of 16 patients with proven cow milk protein intolerance and in only one of the 15 patients without cow milk protein intolerance (p < .01). The RAST for cow milk was positive in six of 16 infants with cow milk protein intolerance and in two of the 15 other infants. Serum IgE level was of no value for the diagnosis of cow milk protein intolerance. Neither of these diagnostic procedures was sensitive enough to be used as a screening test for cow milk protein intolerance. Furthermore, the relationship between specific IgE antibodies for cow milk and the presence of mucosal IgE plasma cells was poor: five of nine infants with cow milk protein intolerance and the presence of mucosal IgE plasma cells had negative RASTs for cow milk.     

Immunogenicity of casein phosphopeptides derived from tryptic hydrolysis of beta-casein

The immunogenicity of phosphopeptides derived from tryptic hydrolysis of beta-casein (CN) was investigated in a rat model system. The titers of specific immunoglobulin (Ig)G and IgE antibodies made in response to intraperitoneal sensitization to beta-CN, casein phosphopeptides, and skim milk proteins were examined using indirect and amplified indirect ELISA, respectively. Serum IgG antibodies from rats injected with beta-CN were significantly more reactive to beta-CN, casein phosphopeptides, and skim milk proteins coated on microtiter plate wells than were the IgG antibodies generated in rats that had been subjected to other treatments. A significant difference in titers because of the time of sampling (14 or 21 d postinjection) was noted for IgE but not for IgG. Rats that were injected with casein phosphopeptides did not produce IgG antibodies that crossreacted with either skim milk proteins or beta-CN. Specific antibody levels for the IgE class rarely exceeded those of unimmunized controls. The findings suggest that immunogenicity of the phosphopeptides was reduced compared with that of native beta-CN and skim milk proteins.