Detection of intracellular cytokines by flow cytometry

During the last years it has become increasingly clear that production of most cytokines is not confined to one cell type. Thus, a method to detect cytokines at the single cell level would be a helpful tool to study the contribution of different cells to cytokine production in heterogeneous cell populations. Recently, Sander et al. (1991) demonstrated that it is possible to detect intracellular cytokines by fixation with paraformaldehyde, permeabilization with saponin and subsequent indirect immunofluorescent staining using fluorescence microscopy. Here, we describe a modified method to increase the specific intracellular staining which enables us to detect IFN-gamma, IL-2 and IL-4 producing cells by single laser flow cytometry. The carboxylic ionophore monensin was used to interrupt intracellular transport processes leading to an accumulation of the cytokine in the Golgi complex. This resulting increase of the signal/noise ratio permitted us to detect weakly fluorescent cells such as IL-4 producing cells. While IL-4 was detected in approximately 1-3% of peripheral mononuclear cells from healthy donors, up to 30% of the cells produced IFN-gamma and nearly 50% IL-2 after phorbol ester and ionomycin stimulation. Microscopic and flow cytometric analysis showed a highly significant correlation. Using three-color flow cytometry it was possible to measure intracellular cytokines and cell surface markers simultaneously. Subpopulations of human T cells (e.g., CD4+ CD45R0-) producing a restricted cytokine pattern could be identified by cell surface staining and were characterized by their cytokine production. Consequently, there was no further need for cell sorting to determine cytokine producing subsets in heterogeneous cell populations. We have tested human T cell clones for intracellular cytokine production and found a high concordance to ELISA analysis of the supernatants. We conclude that detection of intracellular cytokines by flow cytometry is a rapid, easy and semiquantitative assay which may be used to study individual cells in heterogeneous populations as well as to screen homogeneous cells for their cytokine pattern. This method is particularly relevant in view of the accumulating evidence of the functional role that subsets of (T) cells may play in various diseases depending on the pattern of cytokines they produce.     

Detection of intracellular antigens by flow cytometry: comparison of two chemical methods and microwave heating

Detection of intracellular antigens by flow cytometry requires effective fixation and permeabilization of the cell membrane. This study compares three fixation/permeabilization techniques: two commercial chemical reagents, the ORTHOPermeaFix (OPF) and the FIX&PERM Cell Permeabilization Kit (F&P), and a novel method based on microwave heating (MWH). They have been applied to the detection of two nuclear (p53 and rb/p105) and two cytoplasmic (bcl-2 and mdr-1/gp-170) antigens, using positive- and negative-control cell lines and peripheral blood mononuclear cells. Western blotting was performed as a control of protein expression. For the four antigens assessed, cellular morphology, discrimination between intact cells and debris, percentage of positive cells, and mean fluorescence intensity were examined. For this last parameter, the assessment of the MWH technique was performed using SD and a graphical approach inspired by the concepts described by Bland and Altman (Lancet 1986;346: 1085-7) as well as Petersen et al. (Clin Chem 1997;43: 2039-46). The statistical analysis shows that MWH is comparable to the commercial methods and that its reproducibility is also equivalent to OPF and F&P. As assessed for some of the most clinically relevant intracytoplasmic and intranuclear antigens, the MWH method appears to be a valuable and inexpensive alternative. It is worth noting that, unlike commercial reagents, MWH altered surface antigens. Interestingly, this feature, which would prevent cell selection on the basis of combined membrane and intracellular epitopes, is associated with a decrease of nonspecific background fluorescence.     

Detection of myeloperoxidase by flow cytometry in acute leukemia

BACKGROUND: To evaluate long-term results of intraocular pressure after trabeculectomy for congenital glaucoma. METHODS: Data concerning 55 eyes (30 patients) who underwent trabeculectomy for congenital glaucoma were recorded. Mean age at diagnosis was 3.4 months (range: 2 days to 10 months). Mean follow up was 56.8 months. Associated anterior segment abnormalities, need for one or more new trabeculectomy procedures during follow up, and intraocular pressure at the last examination were noted. RESULTS: Of the 55 eyes, 48 met the success criteria (87.3%). A second and sometimes third or fourth trabeculectomy were necessary during follow up in 17 eyes (31%). Of the seven failures at final examination, six (85%) had been diagnosed and operated on before the age of 1 month, whereas 15 of the 48 eyes with good results (31.2%) were in this group (p < 0.02). Of the seven failures at final examination, six (85%) were operated on two to four times, whereas 10 of the 48 eyes with good results (20.1%) were in this group (p < 0.01). An associated anterior segment abnormality was present in 13 eyes (23%), and did not seem to influence the final outcome. CONCLUSION: Trabeculectomy is an effective procedure for long-term control of intraocular pressure in congenital glaucoma. The early diagnosis and surgical treatment correspond to a poor long-term prognosis, probably related to initially severe cases. In these cases, intraocular pressure is difficult to control despite repeated surgical procedures.     

Preliminary study of the basophil activation test for drug allergy using anti-membrane antibodies and flow cytometry

This study deals with the basophil activation test (BAT) in drug allergy, basophil activation being analysed by flow cytometry. In the seven cases studied here (pollen, mite and drug hypersensitivity), we shown that BAT was a reliable test which presented interesting future prospects.     

Anti-seminal plasma antibodies associated with infertility: II. Comparative investigation of human antibody binding to normo-, astheno-, and azoospermic seminal plasma antigens

We present a new method to detect epididymal sperm aneuploidy (ESA) in mice using simultaneous fluorescence in situ hybridization (FISH) with DNA probes specific for mouse chromosomes X, Y and 8. The method was applied to Robertsonian (Rb) translocation (8.14) heterozygotes and homozygotes as well as the chromosomally normal B6C3F1. The sex ratios of sperm did not differ from the expected 1:1 and the hybridization efficiencies were approximately 99.7% for over 60 000 sperm analyzed. Mice heterozygous for Rb (8.14) produced about tenfold higher rates of sperm with chromosome 8 hyperhaploidy than did Rb (8.14) homozygotes or chromosomally normal mice, while frequencies of sperm with hyperhaploidies for chromosomes X and Y were unaffected in all three lines of mice. Hyperhaploid frequencies obtained with the ESA method were consistent with those of the previous testicular FISH method and were validated by published data obtained by conventional cytogenetic analyses (meiotic metaphase II and first cleavage). Thus, the mouse three-chromosome ESA assay together with the previously developed aneuploidy assay for human sperm constitute a promising pair of interspecific biomarkers for comparative studies of the genetic and physiologic mechanisms of the induction and persistence of aneuploidy in male germ cells.     

Ki-67 labeling indices in non-small cell lung cancer: comparison between image cytometry and flow cytometry

Expression of the proliferation-associated nuclear antigen Ki-67 was studied in 27 human non-small cell lung cancers (NSCLCs). We measured immunohistochemical Ki-67 labeling indices using image cytometry (ICM) and flow cytometry (FCM) and compared the indices determined with the two methods. Ki-67 labeling indices of tumor cells ranged from 2% to 59% with ICM, and from 3% to 56% with FCM, varying from case to case. There was a linear correlation of values between the two methods (r = 0.77, P < 0.05). To examine whether Ki-67 labeling indices represent tumor proliferative activity, we studied the relationship between the Ki-67 labeling index and the S-phase fraction determined by FCM. There was a positive correlation between the Ki-67 labeling index and the S-phase fraction (r = 0.91, P < 0.01). Comparison of Ki-67 labeling indices and clinicopathological parameters showed lower Ki-67 labeling indices in well-differentiated tumors than in moderate and poorly differentiated tumors (P < 0.05). No correlation was observed between Ki-67 labeling indices and p53 expression. It was concluded that the Ki-67 labeling index was in fact measured with both ICM and FCM, and that it represents tumor proliferative activity of NSCLCs.     

Differentiation of two strains of Mycoplasma gallisepticum with monoclonal antibodies and flow cytometry

Identification of infecting Mycoplasma spp. is difficult and not routine for strain. This paper describes a procedure for the rapid identification of the strain of M. gallisepticum. Monoclonal antibodies were prepared against M. gallisepticum F and M. gallisepticum S6. Aliquots of 24-hour broth cultures of these organisms were incubated briefly with either of the monoclonal antibodies. A second incubation was made with anti-mouse immunoglobulin conjugated to fluorescein isothiocyanate. Fluorescent intensity associated with the organisms was measured with a flow cytometer. The criterion for identification was a comparative increase in fluorescent intensity when the strain and monoclonal antibody were homologous. The procedure correctly differentiated the F and S6 strains of M. gallisepticum in a blind study.     

Detection of multidrug resistance in patients with leukemia by using flow cytometry and RNA in situ hybridization]

Multidrug resistance (MDR) in leukemia and the reversal of MDR by cyclosporin A (CsA) in vitro have been studied through intracellular accumulation of daunorubicin (DNR) in leukemic myeloblasts. The study was carried out with real-time flow cytometry and relative expression levels of MDR, which is estimated by RNA in situ hybridization in 26 patients suffering from leukemia. The change of intracellular DNR accumulation in vitro after adding CsA was also analyzed. The results showed that intracellular DNR accumulation in newly diagnosed and treated patients (MDR1 negative) with remission increased significantly than that in refractory and relapsing patients (P < 0.01). Good reversal effect was obtained in refractory patients and MDR1 positive relapsing patients by adding CsA (P < 0.01). It is suggested that MDR detection by the two above-mentioned methods could help to project the chemotherapy schedule clinically, CsA had obvious reversal effect on the drug-resistant leukemic cells in vitro.     

A comparison of cytogenetic studies and flow cytometry in breast carcinomas

The increased use of DNA-based typing techniques has improved the accuracy and reliability of HLA types assigned to patients requiring an allogeneic bone marrow transplant and their potential donors, facilitating better donor selection. The benefits of this technology, which will completely replace serologic typing within the next few years, have not yet been fully exploited since the typing information obtained in the form of DNA sequence polymorphisms is presently converted to an HLA allelic type for submission to a registry. Furthermore, within the registry, the allelic type may be further converted to a serologic antigen for use in the search and match process. Because the current nomenclature system makes selection of donors who are likely to provide optimal matches difficult, it is critical that DNA-based HLA typing data be recorded by registries as sequence polymorphisms tested as positive or negative rather than interpreted HLA types and that searching and matching utilize these polymorphisms. Until this transition is complete, we will not fully utilize this powerful HLA typing technology to best serve those patients seeking unrelated donors.     

Simultaneous identification of antibodies to Brucella abortus and Staphylococcus aureus in milk samples by flow cytometry

Two flow cytometric assays are described herein. The single cytometric test (SCT) detects antibodies to either Brucella abortus or Staphylococcus aureus in the serum or milk of a cow or water buffalo. The double cytometric test (DCT) detects both anti-B. abortus and anti-S. aureus antibodies concurrently. In the SCT, the sample to be tested is incubated in succession with the antigen (either B. abortus or S. aureus) and the proper secondary antiserum (fluorescein isothiocyanate-labelled rabbit anti-cow immunoglobulin antiserum or rabbit anti-water buffalo immunoglobulin antiserum). In the DCT, the sample to be tested is incubated first with B. abortus and S. aureus antigens and then with the secondary antiserum. The B. abortus antigen used in the DCT is covalently bound to 3-microm-diameter latex particles. The difference in size between B. abortus and S. aureus permits the establishment of whether the antibodies are directed against one, the other, or both antigens. When compared to the complement fixation test, the SCT and DCT each show a specificity and a sensitivity of 100%. The SCT has been used previously to detect anti-S. aureus antibodies. Here its use is extended to the detection of anti-B. abortus antibodies. The DCT is described here for the first time. The DCT appears to be useful for large-scale brucellosis eradication programs. It offers the possibility of using one test to identify animals that are serologically positive for both B. abortus and S. aureus.     

Formation of antisperm antibodies in women treated with fallopian tube sperm perfusion

Fallopian tube sperm perfusion (FSP) is a combination of ovarian stimulation and intra-uterine insemination using a large volume (4 ml) of inseminate containing 10(7)-10(8) spermatozoa. The inseminate will flush the Fallopian tubes and some of it will end up in the pouch of Douglas. In the present study, we have investigated whether the FSP method will result in the formation of serum antisperm antibodies in the female. A total of 184 treatment cycles were given to 128 women. The indications for treatment were: unexplained infertility (n = 35), various infertility diagnoses (n = 28) and donor insemination (n = 65). Prior to treatment, 11 (8.6%) women had a positive tray-agglutination test (Friberg) and/or a positive immunobead test. After completing one to four treatment cycles, another six (4.7%) women had developed serum antisperm antibodies. The antibodies induced by the treatment were of isotype IgM and directed against the tail-tip of the spermatozoa. Two of the women, who prior to the treatment had antisperm antibodies, showed an increase in antibody titre during treatment. There was no statistically significant difference in the pregnancy rate between the women with antisperm antibodies and the women without. In our opinion, the small risk of developing antisperm antibodies is no contra-indication for treating infertile couples with FSP.     

Detection of K-ras point mutation by in situ PCR in cell suspensions: comparison of the indirect and direct methods

In situ PCR is a new technique for the localization of low copy number sequences. We report here a method for the in situ visualization of a point mutation in K-ras codon 12 by indirect in situ PCR. Twenty-five primers were examined to select mutant-specific primers. Harvested cell lines were fixed and suspended in PCR mixture. Forty cycles of PCR in cell suspension was performed in a thermal cycler using a hot start method. Cells were cytocentrifuged onto slides, and post-fixation was performed. The specimens on the slides were then hybridized with a digoxigenin-labeled probe, followed by color reaction. Both Calu-1 (mutated: TGT) and NCI-H460 (wild type: GGT) cells had strong hybridization signals in the nuclei with general primers. But with mutant-specific primers, only Calu-1 cells had hybridization signals. No signal was observed without primers or Taq DNA polymerase. Southern blotting of the same preparation confirmed desired amplification. We also applied direct in situ PCR, but this method failed to detect the point mutation. We conclude that our indirect in situ PCR method shows the feasibility of in situ identification of single cells carrying point mutations.     

Characterization of Ehrlichia risticii binding, internalization, and proliferation in host cells by flow cytometry

The binding, internalization, and proliferation of Ehrlichia risticii in P388D1 cells and equine polymorphonuclear (PMN) leukocytes were studied by immunofluorescent staining and flow cytometric analysis. The binding of ehrlichiae to P388D1 cells at 4 degrees C was dose dependent, and the antigens of bound organisms were susceptible to pronase treatment. Additionally, the binding of ehrlichiae to P388D1 cells was diminished when either P388D1 cells or ehrlichiae were treated with 1% paraformaldehyde for 30 min or 0.25% trypsin for 15 min. These results indicate that the ehrlichial ligand and host cell receptor are likely surface proteins. Following incubation at 37 degrees C, bound E. risticii and/or its antigens were removed with pronase and indirect immunofluorescent staining in the presence of saponin was used to examine intracellular ehrlichiae. Our results indicate that E. risticii was internalized into P388D1 cells within 3 h and proliferated by 48 h of incubation. The microfilament-disrupting agent cytochalasin D and the transglutaminase inhibitor monodansylcadaverine were used to differentiate between phagocytosis (sensitive to cytochalasin) and receptor-mediated endocytosis (sensitive to monodansylcadaverine) of E. risticii by P388D1 cells. In concentrations that produced distinctive morphological changes and inhibited phagocytosis of polystyrene latex beads, cytochalasin D did not suppress the infectivity of E. risticii. Binding, internalization, or proliferation of E. risticii was not affected by cytochalasin D. However, monodansylcadaverine inhibited infection of E. risticii in a dose-dependent manner. The agent did not affect the attachment of ehrlichiae to host cells, but it did suppress internalization and proliferation. These results suggest that E. risticii is internalized by receptor-mediated endocytosis and that productive infection by E. risticii does not depend on phagocytosis by the P388D1 cells. Although E. risticii did not bind to the surface of equine PMN leukocytes at 4 degrees C, organisms were taken up by this cell at 37 degrees C. E. risticii, however, failed to survive in equine PMN leukocytes.     

The significance of a positive flow cytometry crossmatch test in primary kidney transplantation

This study was conducted to determine the efficacy of the T cell flow cytometry crossmatch (T-FCXM) test in 841 first cadaver donor transplants. Results showed one-year graft survival rates were 82% for T-FCXM-negative patients, compared with 75% for T-FCXM-positive patients (P = 0.01). Early one-month graft failure was 13 percentage points higher in those with a positive T-FCXM than those with a negative T-FCXM. The positive crossmatch patients also had more frequent immunological failures. A positive T-FCXM was found in 39% of the sensitized patients (PRA > 10%) and 8% of those who had not been sensitized. Patients with a positive T-FCXM in either category had a 74% graft survival rate. Thus, most of the T-FCXM-positive results occurred in patients with complement-fixing antibodies. It is suggested that flow cytometry crossmatching (FCXM) be used prospectively, despite the fact that many patients with a positive crossmatch did have successful transplants (TXs). In the current climate of a cadaver kidney scarcity and large recipient waiting pools, utilization of kidneys for patients with the highest probability of success seems a most prudent policy.     

Detection of Moraxella bovis antibodies in infectious bovine keratoconjunctivitis by a passive hemagglutination test

A passive hemagglutination test was developed to detect antibody response to Moraxella bovis in tears. Tannic acid-treated sheep erythrocytes were sensitized with sonicated antigen prepared from M bovis cultures. The test was found to be a relatively simple, specific, and reliable procedure for titrating antibodies in lacrimal secretions. The hemagglutination test could be a valuable method for seroepizootiologic investigation of infectious bovine keratoconjunctivitis.     

Measurement of ceroid accumulation in macrophages by flow cytometry

The accumulation in macrophages of ceroid, an autofluorescent polymer composed of oxidised protein and lipid, can be monitored semiquantitatively by staining techniques. However, such methods are crude and give little information about the amount of ceroid within cells. Flow cytometry, however, can give a quantitative assessment of cellular ceroid accumulation in vitro. Recently, flow cytometry was explored as a method for measurement of the accumulation in macrophages of ceroid. The accumulation appeared to be diminished in the presence of the antioxidant, alpha-tocopherol. This is consistent with the role of lipoprotein oxidation in ceroid accumulation. Here the optimum wavelengths of emission and excitation, using both conventional fluorescence spectroscopy of cellular ceroid and flow cytometric measurements with a number of optical filters, are determined. The use of optimal wavelengths determined in these studies enhances overall sensitivity. The findings are discussed in the context of future investigation of cell-mediated lipid oxidation and its potential antagonists.     

Detection of fetal red cells in fetomaternal hemorrhage using a fetal hemoglobin monoclonal antibody by flow cytometry

OBJECTIVES: To describe clinicians' behavior regarding firearm safety counseling practices, develop a model to predict current counseling behavior, and identify resources that might positively influence willingness to counsel according to medical guidelines. DESIGN: Four hundred sixty-five primary care Los Angeles County, California, pediatricians, family physicians, and pediatric nurse practitioners who serve families with children aged 5 years and younger received mailed questionnaires; 325 (70%) responded. MAIN OUTCOME MEASURE: Clinician self-reported behavior. RESULTS: Of the respondents, 80% stated that they should counsel on firearm safety; only 38% do so. Of those clinicians who currently counsel, only 20% counsel more than 10% of their patient families. Firearm safety counseling behavior is positively associated with a clinician being 49 years or younger (odds ratio [OR]=2.19, P=.02); a perception that counseling is beneficial (OR=2.62, P=.02); and household handgun ownership (OR=2.47, P=.02). Clinician households that report gun ownership counsel differently than those clinicians who report not possessing a household gun. There are no significant differences in the rates of counseling across specialties and crime area types. Forty-one percent of clinicians report that patient education handouts would increase their likelihood of counseling. CONCLUSIONS: In Los Angeles County gaps exist between clinicians' views of the benefits of counseling families with young children regarding firearm safety and their actual behavior. Guidelines and handouts are available from major medical organizations. Research should focus on how to get practitioners to use available materials, enabling them to better adhere to guidelines.     

Circulating antibodies to Chlamydia trachomatis in women: relationship to antisperm and antichlamydial antibodies in semen of male partners

The relation between antibodies to Chlamydia trachomatis and spermatozoa in sera of 112 asymptomatic female partners of infertile couples with no history of C.trachomatis infections and antichlamydial antibodies in semen or antisperm antibodies on ejaculated spermatozoa of their male partners was examined. Samples were tested for immunoglobulin (Ig)A and IgG antibodies to C.trachomatis by enzyme-linked immunosorbent assay; antisperm antibodies in sera and on motile spermatozoa were assayed by immunobead binding. IgG antibodies to C.trachomatis were detected in 24 (21.4%) of the women; only five (4.5%) women were positive for antichlamydial IgA. Antichlamydial IgG was detected in sera from 10 (40.0%) of 25 women whose partners had antichlamydial IgA in semen as opposed to 14 (16.1%) of 87 women whose partners' semen were negative for this antibody (P = 0.02). Similarly, antichlamydial IgG was detected in sera from five (50%) of 10 women whose partners had antichlamydial IgG in semen as opposed to 19 (18.6%) of 102 women whose partners' semen lacked this antibody (P = 0.03). There was no relation between antichlamydial antibodies in women and circulating antichlamydial antibodies in men. A strong correlation (P = 0.001) was observed between IgG antichlamydial antibodies in a woman's serum and antisperm antibodies on ejaculated spermatozoa of her partner [8 of 14 (57.1%) versus 16 of 98 (16.3%)]. Conversely, antichlamydial antibodies in a woman's serum was unrelated to the presence of antisperm antibodies in either her own serum or her partner's serum. The data demonstrate that chlamydial infections of the male genital tract, which are associated with antisperm antibody formation on ejaculated spermatozoa, are likely to be transmitted to the female partner. In contrast, the presence of antichlamydial antibodies in sera does not necessarily appear to indicate an infection of the genital tract and is not associated with the heterosexual transmission of C.trachomatis.     

Oxygen consumption of human seminal plasma: relationships with semen characteristics

It is possible to determine oxygen consumption rate in human seminal plasma through voltammetric measurements. The seminal fluid of the sterile patients in this investigation was characterized by an anomalous sperm motility. Also studied was a control group of proven fertile subjects. The mean value of oxygen consumption resulted greater in the reduced sperm motility group than in the control group. The polyaminoxidase system is the most important factor in oxygen consumption in seminal plasma; however, it is likely that the high toxicity of polyamine degradation products is the cause of reduced and/or anomalous sperm motility in some seminal fluids.