Occurrence and specificity of human natural and in vitro induced antibodies to Nocardia opaca antigens

Nocardia opaca, a Gram-positive bacterium, is a potent source of immunostimulatory substances. Screening of sera of adult human donors revealed that all sera tested contained antibodies reactive with isolated Nocardia fractions (Nocardia delipidated cell mitogen, NDCM; Nocardia lysozyme digest, NLD; Nocardia water-soluble mitogen, NWSM; and fraction B). The respective values of reciprocal titres for IgM and IgG were in the range of 100 to 12,800, and 10 to 320 for IgA antibody isotypes, when NLD or fraction B were used as antigens in enzyme-linked immunosorbent assay (ELISA) tests. The level of antibodies directed to NDCM, a potent polyclonal B cell activator, was found to be the lowest. In vitro spontaneous as well as NDCM-induced production of antibodies to NDCM by human peripheral blood lymphocytes involved mainly the IgM class. Western-blot analysis demonstrated that antibodies in normal human sera react with nocardial antigens of molecular mass approximately 60, 40, 20 and 15-10 kDa. The same antigens were also recognized by rabbit and mouse hyperimmune sera, also confirming the immundominancy of these nocardial antigens in other species. The presence of anti-nocardia antibodies in human sera and their production by both stimulated and non-stimulated lymphocytes points to the natural sensitization of humans either by ubiquitous no-cardial components or by cross-reactive bacterial or food antigens.     

Cross-reactions between mouse Ia and human HLA-D/DR antigens analyzed with monoclonal alloantibodies

Two mouse monoclonal anti-I-E/Ck alloantibodies (H7-8.26 and H10-81.10) directed against 2 distinct determinants of the specificity Ia-7 and 1 anti-I-Ak alloantibody (H8-15.9) directed against a public determinant common to the I-A subregion products of the H-2k, H-2b, H-2d, H-2q, and H-2ja haplotypes identified cross-reactive determinants on lymphoid cells from various mammalian species, including rat, dog, pig, cow, hamster, and guinea pig. In man, these antibodies detected nonpolymorphic determinants of DR antigens on B cell-enriched peripheral blood lymphocytes from 50 unrelated individuals. These cross-reactive DR determinants were also detected on lymphoblastoid B cell lines, on PHA-activated peripheral T lymphocytes, and on allospecific cytolytic T cell clones, but not on various DR-negative human T leukemia cell lines. Two chains of 29,000 and 35,000 daltons m.w., corresponding to DR antigens, were precipitated by H7-8.26 and H8-15.9 antibodies from radiolabeled membrane extracts of Raji cells. Competitive binding experiments indicated that the 3 mouse anti-Iak antibodies identified 3 distinct cross-reactive determinants on human cells. The results indicate that: a) The cross-reactivity described between mouse I-E/C gene products (Ia-7) and human DR antigen(s) involves, in fact, several distinct and topologically distant determinants. b) At least 1 determinant cross-reacting with DR can be identified on I-Ak gene products. c) The intriguing genetic problem of mouse MHC allotypic determinant(s) being nonpolymorphic in man cannot be simply explained by the deletion of an I-E alpha chain in some strains of mice.     

Effect of sulfate on carbon and electron flow during microbial methanogenesis in freshwater sediments

Rickettsiae of the spotted fever group were detected by haemocyte test in 8 (12%) of 51 partially engorged Dermacentor marginatus females collected in March/April 1975 in South Germany. Four strains of rickettsiae were isolated from ticks positive in haemocyte test. It was concluded with isolated strain BRD-1 and homologous immune guinea pig, hamster and mouse sera in CF cross reactions with antigens and immune sera against other members of the SF group, that the newly isolated strains are similar, almost undistinguishable from Rickettsia slovaca.     

Purification and characterization of an agglutinin in the red alga Agardhiella tenera

The red alga, Agardhiella tenera was found to contain a glycoprotein which agglutinates mouse leukemia cells, L5178Y but not L1210. It also agglutinates guinea pig and rabbit erythrocytes, and has weak activity against human A, B and O, mouse, horse and sheep erythrocytes and hamster and mouse lymphocytes. The agglutination was not inhibited by simple sugars. The major active component was purified and determined to be a beta-structure protein containing 2.7% glucose as sugar moiety. The molecular weight was estimated to be 12,000 by gel filtration and 13,000 by polyacrylamide gel electrophoresis, in the presence of sodium dodecylsulfate. Its isoelectric point was 6.1, and it contained high amounts of glycine, serine and threonine, but no half cystine or histidine. It had no subunit structure, and the C- and N-terminal amino acids were threonine and arginine, respectively.     

Interspecies differences in enzymes reacting with organophosphates and their inhibition by paraoxon in vitro

1 Inhibition of cholinesterases (ChE) and carboxylesterases (CaE) by paraoxon (Px) was studied in vitro in the serum, liver, lung and muscle of mouse, guinea pig, rabbit and man (serum only). Moreover, the role of Px hydrolyzing enzyme (Pxase) in the detoxification of Px was studied by inhibiting its activity with EDTA. 2 The ChE and CaE activities as well as their sensitivity to Px varied in different tissues and species. The ChEs were more sensitive than CaEs to Px except in the liver. The CaE activity in human and rabbit sera was low and resistant to Px, indicating that it may have a minor importance for the binding of Px. 3 The Px-inhibited ChEs were spontaneously reactivated in the mouse and rabbit sera during 24 h. In mouse, also the CaE activity was recovered. The presence of EDTA in the incubation medium prevented this reactivation indicating that Pxase takes part in the reactivation process. 4 In rabbit, the serum Pxase activity was very high suggesting a good Px detoxifying capacity of the rabbit serum. 5 The results show that amounts and sensitivities of esterases to OPs in rodents may markedly differ from that in man. Possible species-related differences in the affinity of ChEs and CaEs for OPs and the OP hydrolyzing activity should be taken into the consideration, when animal data are extrapolated to man.     

Disturbances of the blood-brain barrier without expression of amyloid precursor protein- containing neuritic clusters or neuronal loss during late stages of thiamine deficiency in guinea pigs

Generalized oxidative deficits associated with experimental thiamine deficiency (TD) lead to selective neurodegeneration. In mouse brain, TD produces region-specific breach of the blood-brain barrier (BBB), neuronal loss and an accumulation of amyloid precursor protein (APP) in abnormal neurites. The APP-laden abnormal neurites within the damaged areas of mouse brain aggregate into neuritic clusters which strikingly resemble the neuritic component of Alzheimer amyloid plaques. However, amyloid beta-peptide (Abeta) immunoreactivity has not been demonstrated in these neuritic clusters, possibly because the Abeta region of APP in mice contains three amino acid substitutions as compared with the amino acid sequence of human Abeta. In contrast, the guinea pig nucleic acid sequence is more related to the human sequence and the Abeta region is identical in sequence to that of human APP. Thus, the current studies tested whether the presence of an authentic Abeta fragment of APP (i.e., identical to that of man) might make guinea pigs more vulnerable to the development of Abeta-containing neuritic clusters following TD. During late stages of TD, BBB abnormalities, manifested by immunoglobulin G (IgG) extravasation and increased NADPH diaphorase reactivity in microvessels, occurred in brain areas known to be damaged by TD in mice. However, despite the prolonged thiamine deprivation and the advanced neurological symptoms of guinea pigs, no significant neuronal loss or altered APP/Abeta immunostaining occurred in any brain region. Microglial activation, another early marker of damage in mice, was not evident in thiamine-deficient guinea pig brain. Ferritin immunoreactivity and iron deposition in oligodendrocytes within areas of BBB abnormalities were either slightly enhanced or unchanged as compared to controls. This is the first report of brain abnormalities in the guinea pig model of dietary and pyrithiamine-induced TD. The results demonstrate species differences in the response to TD-induced damage, and further support the role of BBB and nitric oxide in the initial events in TD pathology.     

Generation of polyclonal rabbit antisera to mouse melanoma associated antigens using gene gun immunization

Lymphocytes from patients with melanoma have been used to clone melanoma associated antigens which are, for the most part, nonmutated melanocyte tissue differentiation antigens. To establish a mouse model for the use of these 'self' antigens as targets for anti-tumor immune responses, we have employed the mouse homologues of the human melanoma antigens Tyrosinase, Tyrosinase Related Protein-1 (TRP-1), gp100, and MART-1. We sought to generate antisera against these proteins for use in the construction of experimental recombinant and synthetic anti-cancer vaccines, and for use in biologic studies. Using genes cloned from the B16 mouse melanoma or from murine melanocytes, we immunized rabbits with plasmid DNAs coated onto microscopic gold beads that were then delivered using a hand-held, helium-driven 'gene gun'. This strategy enabled us to generate polyclonal rabbit sera containing antibodies that specifically recognized each antigen, as measured by immunostaining of vaccinia virus infected cells. The sera that we generated specifically for TRP-1, gp100, and MART-1 recognized extracts of the spontaneous murine melanoma, B16. The identities of the recognized proteins was confirmed by Western blot analysis. The titers and specificities of these antisera were determined using ELISA. Interestingly, serum samples generated against murine MART-1 and gp100 developed antibodies that were cross-reactive with the corresponding human homologues. Recognition of human gp100 and murine Tyrosinase appeared to be dependent upon conformational epitopes since specificity was lost upon denaturation of the antigens. These antisera may be useful in the detection, purification and characterization of the mouse homologues of recently cloned human tumor associated antigens and may enable the establishment of an animal model of the immune consequences of vaccination against 'self antigens.     

Mammalian transcobalamin II metabolism. The immunological and the biological cross-reactivity of mammalain transcobalamin II

Assay of the reactivity between the chicken anti-rabbit transcobalamin II antiserum and the sera of 19 vertebrate species was carried out by both immuno-diffusion and Sephadex G-200 gel filtration column chromatography. Mammalian transcobalamin II cross-reacted with the antiserum whereas the serum vitamin B-12 binders of the bird, amphibian reptile and fish did not. The biological activity of the purified rabbit transcobalamin II was assessed using reticulocytes or erythrocytes of human, rabbit, guinea pig and rat. The purified rabbit transcobalamin II promoted the uptake of vitamin B-12 by the cells but showed a great variation in its activity. It is suggested that the rabbit transcobalamin II is immunologically and biologically similar to the serum transcobalamin II of the mammalian species studied.     

Inhibition of major histocompatibility complex class I antigen presentation in pig and primate cells by herpes simplex virus type 1 and 2 ICP47

Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) express an immediate-early protein, ICP47, that effectively inhibits the human transporter associated with antigen presentation (TAP), blocking major histocompatibility complex (MHC) class I antigen presentation to CD8+ T cells. Previous work indicated that the mouse TAP is relatively resistant to inhibition by the HSV-1 and HSV-2 ICP47 proteins (ICP47-1 and ICP47-2) and that mouse cells infected with HSV-1 are lysed by anti-HSV CD8+ cytotoxic T lymphocytes (CTL). Therefore, mice are apparently not suitable animals in which to study the in vivo effects of ICP47. In order to find an animal model, we introduced ICP47-1 and ICP47-2 into cells from various animal species-mice, rats, guinea pigs, rabbits, dogs, pigs, cows, monkeys, and humans-and measured TAP activity in the cells. Both proteins were unable to inhibit TAP in mouse, rat, guinea pig, and rabbit cells. In contrast, ICP47-1 and ICP47-2 inhibited TAP in pig, dog, cow, and monkey cells, and the TAP in pig and dog fibroblasts was often more sensitive to both proteins than TAP in human fibroblasts. These results were extended by measuring CD8+-T-cell recognition (CTL lysis) of cells from various species. Cells were infected with recombinant HSV-1 constructed to express murine MHC class I proteins so that the cells would be recognized and lysed by well-characterized murine anti-HSV CTL unless antigen presentation was blocked by ICP47. Anti-HSV CD8+ CTL effectively lysed pig and primate cells infected with a recombinant HSV-1 ICP47- mutant but were unable to lyse pig or primate cells infected with a recombinant HSV-1 that expressed ICP47. Therefore, pigs, dogs, and monkeys may be useful animal models in which to test the effects of ICP47 on HSV pathogenesis or the use of ICP47 as a selective immunosuppressive agent.     

Sequence and functional analysis of cloned guinea pig and rat serotonin 5-HT1D receptors: common pharmacological features within the 5-HT1D receptor subfamily

This study was undertaken to investigate the pharmacology of cloned guinea pig and rat 5-hydroxytryptamine (serotonin; 5-HT)1D receptor sites. Guinea pig, rat, and mouse 5-HT1D receptor genes were cloned, and their amino acid sequences were compared with those of the human, dog, and rabbit. The overall amino acid sequence identity between these 5-HT1D receptors is high and varies between 86 and 99%. The sequence homology is slightly more divergent (13-27%) in the N-terminal extracellular region of these 5-HT1D receptors. Guinea pig and rat 5-HT1D receptors, stably and separately expressed in rat C6 glial cells, are negatively coupled to cyclic AMP formation upon stimulation with agonists, as previously found for cloned human 5-HT1D receptor sites. The cyclic AMP data show some common pharmacological features for the 5-HT1D receptors of guinea pig, rat, and human: an almost similar rank order of potency for the investigated 5-HT1D receptor agonists, stereoselectivity for the binding affinity and agonist potency of R(+)-8-hydroxy-2-(di-n-propylamino)tetralin, and equal 5-HT1D receptor-mediated antagonist potency for methiothepin and the 5-HT2 receptor antagonists ritanserin and ketanserin. In conclusion, the pharmacology of the cloned 5-HT1D receptor subtype seems, unlike the 5-HT1B receptor subtype, conserved among various mammal species such as the human, guinea pig, and rat.     

Cytotoxic effects of islet cell surface antibodies

Antibodies against rat islet cells were produced by immunisation of rabbits with neonatal rat islet cells. In the presence of complement the rabbit anti-rat islet cell surface sera were strongly cytotoxic for both, neonatal rat islet cells and spleen lymphocytes as revealed by the high percentage of 51Cr release from these cells. However, after absorption with rat lymphocytes and rat liver powder the cytotoxicity of the islet cell antisera for rat lymphocytes was drastically reduced while the release of 51Cr from islet cells was only slightly influenced. These data indicate that islet cell specific antibodies were still present in the antisera after absorption. Native normal rabbit serum was also cytotoxic for neonatal rat islet cells and spleen lymphocytes. The release of 51Cr from islet cells and lymphocytes was vigorously reduced after absorption of the normal rabbit serum with lymphocytes and was paralleled by a similar decrease of insulin release from intact islets under conditions where the active insulin secretion was blocked pharmacologically. Intact islets prelabeled with 51Cr were also used as targets but this approach was less suitable for the detection of cytotoxic islet cell surface antibodies.     

Influence of pathologic scotopization on the extended Rayleigh match

Specific antigens of virulent strains of Chlamydia psittaci isolated from ruminants were characterized by western blotting. The immunoblot analyses were performed with chlamydial elementary bodies from abortive (AB7 strain) or intestinal (iB1 strain) chlamydiae using mouse and rabbit immune sera raised against viable chlamydiae or proteic extracts. Eleven antigens were found to be AB7-specific, but only 4 (96, 90, 88 and 49-50 kDa) were recognized by both mouse and rabbit sera against viable AB7 strains. These could be candidates for specific diagnosis of caprine and ovine abortive chlamydiosis. No iB1-specific antigen recognized by mouse and rabbit anti-sera could be identified.     

Electrical parameters in gallbladders of different species. Their contribution to the origin of the transmural potential difference

Amphotericin B enhances Na+ conductance of the mucosal membrane of gallbladder epithelial cells and in such a way it modifies the brush border electromotive force. On this basis a method to measure cell and shunt resistances by comparing changes of the mucosal membrane potential (Vm) and of the transmural p.d. (Vms) is developed. This method is applied in gallbladders of different vertebrate species (i.e. rabbit, guinea pig, goose, tortoise, toad, trout). The two tested mammals, rabbit and guinea pig, exhibited a lower shunting percentage (89--93%) than the nonmammals (96--97%), but this fact did not bring about a homogeneous positive Vms. This means that shunting percent contributes, but it is not the only source of differences in Vms, in accordance with that reported by Gelarden and Rose (J. Membrane Biol. 19:37, 1974). Moreover, mammals exhibited a lower luminal resistance and a lower ratio between luminal and basolateral resistance than nonmammals. Possible causes of these differences are discussed.     

Perspective on allogeneic melanoma lysates in active specific immunotherapy

PURPOSE: To compare calcium ionophore-induced cataract formation and in vitro light scattering in cultured lenses from guinea pig and rabbit. METHODS: Lenses from guinea pig and rabbit were cultured for 5 or 6 days with calcium ionophore A23187. To assess the involvement of calpain in cataract formation; SDS-PAGE, immunoblotting and calcium determinations were performed. For in vitro light scattering, lens soluble proteins from rabbit were hydrolyzed for 24 h by either endogenous lens calpain, or by addition of purified m-calpain and then further incubated for up to 10 days. Light scattering was measured daily at 405 nm. RESULTS: Lenses from younger guinea pigs cultured in A23187 first developed outer cortical opacities followed by nuclear cataract. Total calcium was markedly increased by A23187 in lenses of all ages. Proteolysis of crystallins and alpha-spectrin were observed in nuclear cataract in younger guinea pigs. This was attenuated with age, in association with the attenuation of cataract formation with age. Calpain 80 kDa subunit in the lenses cultured with A23187 was also decreased. Co-culture with SJA6017 or E64d (reversible and irreversible inhibitors of calpain, respectively) reduced A23187-induced nuclear opacities, proteolysis of crystallins and alpha-spectrin, and loss of calpain without affecting increased total calcium. In contrast, rabbit lenses cultured in A23187 did not develop nuclear cataract, although biochemical changes in cultured rabbit lenses were similar to those in cultured guinea pig lenses. Furthermore, no appreciable in vitro light scattering occurred in soluble proteins from rabbit lenses after activation of endogenous m-calpain, or after addition of exogenous purified m-calpain, although crystallins were partially hydrolyzed by calpain. CONCLUSIONS: Both rabbit and guinea pig lenses undergo calpain-induced proteolysis upon elevation of lenticular calcium. However, factors in intact guinea pig lenses may promote light scattering and insolubilization after proteolysis by calpain, but these factors were not functional in rabbit lenses. Discovery of the factors promoting light scatter and insolubilization after proteolysis will help to explain the role of certain crystallin polypeptides in cataract formation.     

Generation of cytotoxic immune responses during the progression of a rat glioma

Cytotoxic T lymphocytes specific for tumor-associated antigens are produced by exposing animals to tumor cells and stimulating lymphocytes from animals immunized in vitro with tumor cells and small amounts of interleukin-2 (IL-2). This study was designed to determine whether a fast-growing immunogenic avian sarcoma virus-induced glioma produces primed cytotoxic T lymphocyte precursors during its progression. Lymphocytes from intracerebral glioma-bearing rats generally failed to proliferate in vitro in response to immunization with tumor cells and IL-2 and, when proliferative responses were observed, the lymphocytes were not cytotoxic for glioma cells. However, when the same tumor was growing subcutaneously, lymphocytes proliferated and exhibited glioma-specific cytotoxicity when stimulated in vitro with autologous tumor cells and IL-2. Subcutaneous immunization of intracerebral glioma-bearing rats with tumor cells and adjuvant induced strong cytotoxic T lymphocyte responses. The results demonstrated that, while intracerebral tumor progression itself does not induce an anti-glioma immune response, immune responses to tumor-associated antigens may be induced by systemic immunization of tumor-bearing animals. The results suggest that the immunogenicity of brain tumors is masked by the immunologically privileged status of the brain, not by the induction of generalized immune suppression during tumor progression.     

Tissue distribution of histamine N-methyltransferase-like immunoreactivity in rodents

The rat kidney histamine N-methyltransferase was purified to homogeneity from Escherichia coli transfected with its recombinant cDNA. An antiserum to the enzyme was raised in rabbit by immunization with the purified protein. Western blot analysis of rat tissues with the antiserum revealed a band with identical mobility to that of purified enzyme in the extracts of kidney, jejunum, and brain, where the enzyme activity was detected. The antiserum cross-reacted with a 32K protein in mouse liver, brain, stomach, kidney and lung, and a 33K protein in guinea pig brain, stomach jejunum, spleen, lung, and kidney. The intensity of the staining in western blotting correlated well with the enzyme activity in all the tissues in these three species, suggesting that our antiserum is useful for quantifying histamine N-methyltransferase protein in rodent tissues.     

In vitro activation of mouse macrophages by rat lymphocyte mediators

Macrophage-activating factors (MAF)3 were released by presensitized rat lymphocytes stimulated in vitro with the appropriate antigens. Different supernatants of presensitized rat lymphocytes specifically stimulated in vitro with several different mouse, dog, and rat tumor or normal cells were capable of rendering normal rat and mouse macrophages nonspecifically cytotoxic in vitro to their respective syngeneic tumor cells. The release of active mediators by rat lymphocytes sensitized in vivo was dependent upon immunologically specific recognition of an antigen in vitro. When rat lymphocytes were incubated in vitro with antigens unrelated to the in vivo sensitizing antigens, no release of MAF occurred. Once rat MAF was released, it activated both syngeneic (rat) and xenogeneic (mouse) macrophages to kill tumor cells in vitro. These activated marcophages destroyed all syngeneic tumor targets. Such cytotoxicity was obtained even when the cells used to elicit release of MAF were totally unrelated to the target tumor cells. The data thus demonstrated that MAF can cross strain and even species specificities and can activate macrophages to kill tumors in a nonspecific manner. The cytotoxicity mediated by in vitro activated mouse macrophages decreased with time once the macrophages were removed from MAF; and by 7 days postactivation, the macrophages were not cytotoxic. However, when incubated again with MAF, significant reactivation was observed. This suggested that activation of macrophages in vivo may be a continuous process of lymphocyte-macrophage interaction.     

Fate of rubella genome ribonucleic acid after immune and nonimmune virolysis in the presence of ribonuclease

To determine whether rubella virion ribonucleic acid (RNA) becomes accessible to nuclease attack after immune lysis of the viral envelope, virions containing radioactively labeled RNA were examined in three ways with the following results. (i) Incubation of purified virus with heat-inactivated rubella convalescent human serum and guinea pig complement resulted in an increase in acid-soluble RNA. Antibody was required; the reaction was temperature dependent and was blocked by ethylenediaminetetraacetic acid. When exogenous nuclease was added prior to lysis, radioactivity in virions was reduced to 15% of that in unlysed control pellets (ii) Sucrose gradient sedimentation profiles of RNA released from lysed and unlysed virions under controlled conditions showed that the nuclease content of serum-virus mixtures was sufficient to eliminate all RNA of genome size, although degradation was not complete. (iii) Virions were also lysed by unheated human immune sera in the absence of guinea pig complement and by some, but not all, unheated antibody-negative sera.     

The antigen (CANDTEC antigen) detected by CAND TEC test for diagnosis of candidiasis

Most guinea pigs inoculated with 5.4 x 10(9) of C. albicans intraperitoneally, produce CANDTEC antigen (GPCANDTECAG) in sera. The antigen is heat-labile (at 56 degrees C for 30 min) as is that in humans. According to gel filtration, the molecule size of the antigen from guinea pigs was 4000KDa or more. ELISA revealed the antigen-positive gel fractions to contain a small amount of mannan from the yeasts and C3. ELISA using rabbit anti-GPCANDTECAG serum indicated that the two CANDTEC antigens from guinea pigs and humans shared determinants. Gel filtration indicated that the CANDTEC antigen from patients was from 4000KDa to 3000KDa. In the antigen-positive gel fractions, IgM was detected by ELISA, but mannan and C3 were not detected. However, immunoblotting analysis on the antigen-positive fraction revealed a unique band of 200KDa, stained with concanavalin A-ALP. These findings indicate that CANDTEC antigens in guinea pigs and humans are immune complexes formed after infection of Candida, although the antigens have different components.     

Overload syndromes of the peritalar region

BACKGROUND: The purpose of this study was to investigate lymphocyte adhesion to Kupffer cells as a component of an immune-mediated mechanism for halothane hepatitis. METHODS: Kupffer cells were isolated from guinea pigs exposed to 1.0% halothane/40% oxygen and cultured with various synthetic antigens (trifluoroacetyl-protein adducts or hepatocyte homogenate from halothane-exposed animals). Latex beads were also added to Kupffer cell cultures to determine if activation of these macrophages would result in an increased cellular adhesion. Lymphocytes which had been surfaced-labeled with biotin were added to treated Kupffer cells, and lymphocyte adhesion was determined using a streptavidin-peroxidase reagent for colorimetric detection. RESULTS: Trifluoroacetyl-lysine, trifluoroacetyl-rabbit albumin or guinea pig albumin did not induce lymphocyte adhesion. Latex beads also had no effect on cellular adhesion. A noticeable increase in lymphocyte adhesion to Kupffer cells previously treated with either trifluoroacetyl-guinea pig albumin or hepatocyte homogenate was observed. Stimulation of lymphocytes with phorbol myristate acetate did not have an effect on adhesion. Addition ofantimajor histocompatibility complex II antibody had a significant inhibitory effect on lymphocyte adhesion to Kupffer cells treated with trifluoroacetyl-guinea pig albumin or homogenate. CONCLUSION: These results demonstrate that the halothane trifluoroacetyl-guinea pig albumin antigen and hepatocyte homogenate enhances the adhesion of lymphocytes to cultured Kupffer cells and that this interaction involves major histocompatibility complex II expression on stimulated Kupffer cells. The interaction between Kupffer cells which present specific trifluoroacetyl-antigens and lymphocytes from halothane-exposed animals may play an important role in the pathogenesis of halothane hepatitis.