Heterogeneity of macrophage populations in human lymphoid tissue and peripheral blood

Human lymphoid tissue and peripheral blood leukocytes were stained with six monoclonal antibodies directed against monocyte/macrophage populations. The staining pattern described by each of these monoclonal reagents was compared with the distribution of morphologically distinguishable tissue macrophages. The results show that there exists considerable heterogeneity of tissue macrophages based on the expression of surface and/or cytoplasmic antigens; furthermore, the distribution of cells bearing particular antigenic determinants is associated with distinct regions in normal lymphoid tissue. Double staining methods demonstrated that these antibodies bind to different, as well as to identical, macrophage populations. OKM-1 antibody binds predominantly to sinus histiocytes and tingible body macrophages. The Leu M-1 reagent stains interdigitating reticulum cells, while the KiM-4 antibody labels follicular dendritic cells. Leu M-3 antibody identifies cells predominantly in the germinal center, and histiocytes lining the sinuses. Both CM-1 and BRL-M.1 appear to stain tissue macrophages distributed throughout the lymphoid tissue.     

Comparative efficacy of laboratory methods for cytomegalovirus detection in autopsy material

Eighty eight autopsy specimens obtained from 30 fetuses, still-borns and infants died during the first year of life, all suspected for congenital virus infection at postmortem examination, were studied. The specimens were analyzed by 3 techniques: rapid culture method (RCM) for detection of cytomegalovirus (CMV) infectious activity, the immunocytochemical method for detection of CMV antigen in prints of organs and polymerase chain reaction (PCR) for detection CMV DNA. CMV was detected in 16 out of 26 specimens (61.5%) by PCR, in 43 out of 88 specimens (49%) by RCM and in 15 out of 64 specimens (23%) in prints. The comparison of immune reagents revealed that monoclonal antibodies (McAb) were more specific than polyclonal serum antibodies, as the latter yielded the positive reaction in 10 out of 26 cases (38%), found to be negative in PCR. The data thus obtained indicate that complex techniques, including PCR and RCM in combination with McAb, should be used for evaluation of CMV infection role in child mortality.     

Cross reactive identification of types 1 and 2C fibers in human skeletal muscles with monoclonal anti-neurofilament (200 kd) antibody

Types 1 and 2C fibers in human skeletal muscle were cross-reactively identified with monoclonal anti-bovine neurofilament (200 kd) antibody. Thirty seven biopsy samples including sixteen vastus lateralis muscles, twelve lumbar paravertebral muscles, six gluteus medius muscles, two flexor carpi ulnaris muscles, and one flexor pollicis longus muscle, were examined. Serial transverse sections were stained histochemically with myofibrillar ATPase (pH 10.4, 4.6, 4.3) and DPNH-tetrazolium reductase reactions, and immunochemically using the avidin-biotin-peroxidase complex with the primary antibodies of monoclonal anti-bovine neurofilament (200 kd, 160 kd, 70 kd) antibodies and anti-bovine glial filament acidic protein antibody. The immunochemical reaction with anti-NF (200 kd) antibody could distinguish two kinds of fibers; positive and negative in all of the specimens. No fiber was recognized with other antibodies. Myosin ATPase reactions in serial sections proved that the positively stained fibers with anti-NF (200 kd) antibody were types 1 and 2C fibers and negative fibers types 2A and 2B fibers. At present, it is not known what substance is responsible for the cross-reaction with the monoclonal anti-NF (200 kd) antibody in types 1 and 2C fibers, but this unique antibody would be valuable in two aspects: one concerns the problem of the evolution of fiber types, and the other the utility as another supplemental method to conventional myosin ATPase scheme.     

Monoclonal antibodies as a tool for phylogenetic studies of major histocompatibility antigens and β 2-microglobulin

The cross-reactivity of several monoclonal antibodies recognizing monomorphic determinants of human HLA-A, B, C, and DR antigens and human 2-microglobulin (2m) has been studied on peripheral blood leukocytes in 24 different species. An monoclonal HLA-A-, B-, and C-specific antibody and four monoclonal HLA-DR-specific antibodies cross-reacted with cells from all the primate species tested. Furthermore, antibodies HLA-DR-specific were positive with peripheral blood leukocytes (PBL) from cows, goats, sheep, horses, and dogs. Two monoclonal 2m-specific antibodies, which were positive with PBL from certain primates, also reacted with cells from cows, goats, sheep, horses, and dogs. Two other #2m-specific antibodies reacted only with PBL from chimpanzees. No reaction could be detected with all our reagents in other classes tested (birds, reptiles, amphibians, and Teleostei).     

The use of a panel of monoclonal antibodies in the evaluation of cytologic specimens from the central nervous system

A panel of monoclonal antibodies was tested immunohistochemically to determine the utility of such reagents in distinguishing among metastatic carcinoma, lymphoma, leukemia and primary brain tumors. The monoclonal antibodies used were: (1) a cocktail comprised of three anti-glial fibrillary acidic protein antibodies (alpha-GFAP); (2) UJ13A, a panneuroectodermal antibody; (3) B72.3, which recognizes a carcinoma-distinctive tumor-associated glycoprotein complex; and (4) 2D1, a pan-leukocyte antibody. Fifty-three specimens (21 cerebrospinal fluids, 1 ventricular fluid, 2 brain cyst fluids, 12 needle washings, 15 imprints, 1 subdural fluid and 1 post-shunt fluid) were obtained from 21 gliomas, 2 meningiomas, 1 pineoblastoma, 11 metastatic tumors, 3 lymphomas, 1 leukemia and 14 cases without tumor. alpha-GFAP stained all 21 gliomas and 5 of 5 cases containing reactive brain fragments. UJ13A had a reactivity pattern similar to that of alpha-GFAP, but also stained the meningiomas, pineoblastoma, oat-cell carcinoma and embryonal rhabdomyosarcoma. B72.3 stained all adenocarcinomas and the large-cell carcinoma. 2D1 stained lymphoma and leukemia, all inflammatory cells and 4 of 12 glioblastomas. Although no single antibody was diagnostic of a specific tumor type, this panel accurately differentiated among most primary brain tumors, metastases, leukemias and lymphomas.     

抗乙型肝炎病毒e抗原和核心抗原双特异性单克隆抗体的建立与应用

用基因工程技术在大肠杆菌中高效表达的乙型肝炎病毒核心抗原(内含高滴度的e抗原)免疫Balb/C小鼠,取免疫小鼠脾细胞与小鼠骨髓瘤细胞(Sp2/0)融合,获得两株分泌高滴度既抗-HBe又抗-HBc的双特异性杂交瘤细胞系。细胞培养上清液中抗体滴度为100～1000以上;免疫腹水中的抗体滴度为8万至10万以上,均属IgG2a亚类。细胞在实验室连续传代二年多,仍保持高效分泌抗体能力。此单克隆抗体与HBeAg或HBcAg的结合可被抗-HBc或抗-HBc阳性血清所抑制,竞争抑制率在85.9％～96.8％之间。用此单克隆抗体与HBe的β型单克隆抗体和抗HBc的α型单克隆抗体配对,可组装成检测HBeAg/抗-HBe和抗-HBc的诊断试剂,具有重要的应用价值。     

Site-specifically modified 111In labelled antibodies give low liver backgrounds and improved radioimmunoscintigraphy

Site-specific modification of monoclonal antibodies at their oligosaccharide had previously been demonstrated to produce excellent ¹¹¹In imaging in a xenograft model using a Brown Norway (BN) rat lymphoma and a rat anti-BN MHC monoclonal antibody [Lee C. et al. Fed. Proc. Abstr. 43 3014 (1984)]. These results are due, in part, to lack of liver uptake, so we wanted to evaluate the extent of hepatic uptake observed with different monoclonal antibodies in normal mice. Biodistribution data were obtained for four monoclonal antibodies by first modifying each antibody at its carbohydrate with a diethylenetriaminepentaacetic acid (DTPA) derivative. The antibodies were then labelled with ¹¹¹In and injected into normal mice. Images were obtained 24 h post-injection, and at 48 h the mice were dissected and the tissue-to-blood (T:B) ratios determined. T:B ratios were approximately 1 (or less) for every organ evaluated, indicating minimal non-specific uptake into these organs. Data is also presented for the BN-rat system which shows excellent localization into the tumor xenograft and low non-specific organ uptake. These data indicate that modification of antibodies site-specifically at their oligosaccharide results in minimal non-specific uptake into non-target tissues and enhanced localization into the tumor target, and that this may represent a preferred method for production of ¹¹¹In labelled antibodies.     

Medullary Thyroid Cancer that Stains Negative for CA 19-9 has Decreased Metastatic Potential

Objective: Presently, no clinical tools are available to diagnose the metastatic potential of medullary thyroid cancer (MTC) at disease presentation. Surveillance with calcitonin (Ct) and carcinoembryonic antigen (CEA) is currently recommended for the observation and diagnosis of metastatic disease after initial treatment of MTC. Recently, carbohydrate antigen (CA)19-9 staining has been associated with aggressive forms of MTC and metastatic spread. This pilot study explored whether positive CA19-9 staining of MTC tissue is associated with its metastatic potential.Methods: Sixteen cases of MTC were identified, and tissue specimens were immunostained for CA 19-9 and other MTC tumor markers. Clinical information about patients' MTC was collected through a retrospective chart review.Results: Overall, 63% of the specimens stained positive for CA19-9. The median size of positively staining specimens was 2.6 cm (interquartile range [IQR] 1.2-3.2) compared to 0.7 cm (0.5-1.2) in negatively staining MTC specimens (P = .04). All specimens from patients diagnosed with stage IV MTC stained positive for CA19-9, compared to only 40% of cases that were classified as stages I to III (P = .03). Furthermore, 100% of the primary specimens that were documented to have metastatic spread stained positive for CA19-9. The sensitivity for ruling out stage IV MTC based on negative staining for CA 19-9 was 100%.Conclusion: Based on these results, we conclude that negative staining of MTC for CA19-9 may be associated with its decreased metastatic potential.Abbreviations: CA = carbohydrate antigen CEA = carcinoembryonic antigen Ct = calcitonin IHC =immunohistochemistry MTC = medullary thyroid cancer     

Suitability of yeast- and Escherichia coli-expressed hepatitis B virus core antigen derivatives for detection of anti-HBc antibodies in human sera

Antibody to hepatitis B virus core antigen (anti-HBc) is one of the most important serological markers during hepatitis B virus (HBV) infection. The quality of the hepatitis B virus core antigen (HBcAg; diagnostic antigen) is crucial to the accuracy of anti-HBc detection. In an attempt to explore the suitability of recombinant HBcAg (rHBcAg) for diagnostic purposes, HBcAg was expressed in Escherichia coli (E. coli) and Pichia pastoris (P. pastoris) and evaluated for the detection of anti-HBc. The expression level of the recombinant protein satisfied the criteria for large-scale biologic production. P. pastoris- and E. coli-derived rHBcAg were purified with gel filtration followed by sucrose gradient (reagents A and C) or with a monoclonal anti-HBc antibody binding (reagents B and D) and were utilized to detect anti-HBc in competitive inhibition enzyme-linked immunosorbent assay (ELISA) format. The ELISA using P. pastoris-derived rHBcAg had a higher specificity and sensitivity than that using E.coli-derived rHBcAg to detect the anti-HBc standard panel. Serum specimens were collected from HBV-infected patients and healthy individuals (voluntary blood donors). Anti-HBc was detected in those specimens using P. pastoris- and E. coli-derived rHBcAg. The positive rate of anti-HBc detection in HBV-infected patients' sera was 100% with reagents A and B, 96.4% with reagent C, and 93.6% with reagent D. The negative rate in healthy control sera was 100% with reagents A and B, 97.0% with reagent C, and 99.7% with reagent D. These data indicate that P. pastoris-derived rHBcAg is superior to E.coli-derived rHBcAg for the detection of anti-HBc using the diagnostic ELISA.     

Immunocytochemistry of brain-reactive monoclonal antibodies in peripheral tissues

Among a total of 135 tissue-reactive monoclonal antibodies previously prepared, 81 were brain-selective and were classified into neuronal and non-neuronal categories. The neuronal antibodies were again subdivided into antineurofibrillar, antiperikaryonal-neurofibrillar, and antisynapse-associated groups. On the basis of morphologic, developmental, biochemical, and pathologic criteria, the antibodies in at least two of these groups were found to detect heterogeneous antigens (called "neurotypes") rather than different antigenic determinants in single antigens. On examining the distribution in peripheral organs of staining patterns of 11 antineuronal brain-reactive antibodies, we now confirm that these antibodies are, indeed, largely brain-specific. In general, non-neuronal elements in liver, lung, heart, thymus, intestine, adrenal, and spleen remained unstained. However, most of the antibodies stained peripheral neural elements. Occasional antibodies did stain selected, non-neuronal structures. Four out of five antineurofibrillar antibodies stained nerve fibers in adrenal medulla, intestine and thymus. All of three antiperikaryonal-neurofibrillar antibodies also stained nerve fibers in the adrenal medulla, but not in other organs. Two out of three antisynapse-associated antibodies stained what appear to be nerve contacts on adrenal medullary cells, but not on any other peripheral cells examined. The non-neuronal peripheral staining patterns were restricted to selective nuclear staining exhibited by two out of five antineurofibrillar antibodies and the staining of macrophage and selected cardiac muscle nuclei by two of three antisynapse-associated antibodies. However, one antineurofibrillar antibody also stained the cytoplasm of selected liver cells. Among non-neuronally reacting antibodies, two antibodies stained nuclei of all cells except neurons in brain as well as peripheral organs. An antibody staining the ciliary epithelium of choroid plexus also stained basal bodies of ciliated bronchial epithelium. The overall data suggest that the specificity of brain-reactive antibodies is high and that their cross-reactivity with epitopes in non-nervous tissue is rare. In these cases, the antibodies seem to provide specific reagents for these additional structures as well as for their specific brain antigens.     

Unidirectional potentiation of binding between two anti-FBP MAbs: Evaluation of involved mechanisms

The monoclonal antibody MOv19 directed to a folate binding protein shows temperature-dependent potentiation of binding of the noncompeting monoclonal antibody MOv18 to the relevant antigen, but the mechanism involved in this phinomenon had remained unclear. Use of chimeric versions of both monoclonal antibodies and the F(ab′)₂ and fan fragments of MOv19 revealed an increment in MOv18 binding in all combinations irrespective of the orgin of the Fc portin of the monoclonal antibody. The potentiating effect of bivalent MOv19 fragments on ¹²⁵l-MOv18 binding was similar to that of the entire monoclonal antibody and occurred at saturating concentrations of both reagents at which monovalent binding prevails. Similarly, the monovalent fragment also induced a significant increase in MOv18 bunding. Howener, the potentiation sccurred only at very high concentrations of antibody fragment. Homologous inhibition was drastically reduced using MOv19 Fab fragment, suggesting a low binding stability of the monovalent reagent. Immunoblotting analysis and binding in the presence of exogenous purified folate binding protein indicated a cross-linking between soluble and cell surface molecules mediated by the bivalent monoclonal antibodies. The extentof the increase in MOv18 binging at O°C with high amounts of exogenous folate binding protein was lower than that obtained at 37⁰C in the absence of added molecule. Release of ¹²⁵l-MOv18 from the cell surface was significantly higher in the absence of MOv19 than in its presence. Affinity constant values of ¹²⁵l-MOv18 binding evaluated in the presence of MOv19 or control monoclonal antibody MINT5 were comparable, whereas the number of binding sites per cell detected by ¹²⁵l-MOv18 was significantly higher in the presence of MOv19 than MINT5. Together, the data suggest that monoclonal antibody MOv19 induces a conformational change of the molecule it binds that increases the number of antigenic sites anvailable for MOv18 binding and, in turn, the binding stability of the latter, MOv19 bivalency also contributes to the MOv18 binding increment by cross-linking released and cell surface–anchored folate binding protein molecules. © Wiley-Liss, Inc.     

Generation of hybridomas producing human monoclonal antibodies against human cytomegalovirus

In vitro stimulation of human lymphocytes were studied in connection with cell fusion. When splenic lymphocytes were stimulated with human cytomegalovirus (CMV), they produced IgG but not IgM antibody against CMV. The stimulation with 50 ng/ml of CMV antigen induced the maximum antibody response, and higher concentrations of CMV antigen decreased antibody response and increased nonspecific IgG production. Human splenic lymphocytes were stimulated for 6 days with CMV antigen (50 ng/ml) and/or B-cell growth factor (BCGF), and then fused with mouse myeloma cells. Stimulation with a combination of antigen and BCGF were able to generate CMV-specific hybridomas synergistically. Two of these hybridomas were cloned by limiting dilution. The human monoclonal antibodies produced by them, C1 and C23, bound to CMV but not to other herpesviruses. C23 neutralized virus infectivity C1 did not at all. This method for generation of hybridomas producing human monoclonal antibodies against a predefined antigen may be applicable to a variety of viral antigens.     

Production of a diagnostic monoclonal antibody in perennial alfalfa plants.

The increasing use of monoclonal antibodies (mAbs) in diagnostic reagents necessitates efficient and cost-effective mAb production methods. In blood banks, one of the most routinely used reagents is the anti-human IgG reagent used for the detection of non-agglutinating antibodies. Here we report the production of a functional, purified anti-human IgG, through the expression of its encoding genes in perennial transgenic alfalfa. Transgenic plants expressing the light- and heavy-chain encoding mRNAs were obtained, and plants from crosses were found to express fully assembled C5-1. The purification procedure yielded mainly the H2L2 form with specificity and affinity identical to those of hybridoma-derived C5-1. The ability to accumulate the antibody was maintained both in parental F1 lines during repeated harvesting and in clonal material; the antibody was stable in the drying hay as in extracts made in pure water. Also, plant and hybridoma-derived C5-1 had similar in vivo half-lives in mice. These results indicate that plant C5-1 could be used in a diagnostic reagent as effectively as hybridoma-derived C5-1, and demonstrates the usefulness of perennial systems for the cost-effective, stable, and reliable production of large amounts of mAbs.     

Use of monoclonal antibody blends in the identification of enteroviral aseptic meningitis

Monoclonal antibody pools directed against group B coxsackievirus and echovirus antigens (Chemicon, Temecula, California) were evaluated as tools in the identification of enteroviral aseptic meningitis. Cerebrospinal fluid (CSF) and serial dilutions of stock coxsackievirus were inoculated into tube and shell vial Rhesus monkey kidney (RhMk) cell cultures. Positive cellular fluorescence was observed only in conjunction with cytopathic effect (CPE). The time from inoculation to CPE was similar with both tube and shell vial cultures.Direct CSF testing failed to reliably identify positive specimens as fluorescent debris, and a lack of available cells hindered results.Viral components of each antibody blend demonstrated positive cellular fluorescence when appropriately stained. False-positive fluorescence was not observed when cells, infected with other CSF viruses, were stained with these reagents.The findings suggest a role for these reagents (available both as blends and type-specific reagents) in the culture confirmation and identification of many common enteroviral serotypes associated with aseptic meningitis.     

The T3/T cell receptor complex: antigenic distinction between the two 20-kd T3 (T3-delta and T3-epsilon) subunits.

Clonally distributed (clonotypic) antigen receptors on human T lymphocytes (alpha and beta chains) are associated with three invariable T3 polypeptide chains (T3 gamma, delta and epsilon), together forming the T3/T cell receptor complex. Monoclonal antibodies prepared against the two 20-kd T3 polypeptide chains demonstrated that T3-delta and T3-epsilon are distinct polypeptide chains. Only one monoclonal antibody (anti-T3-delta chain) reacted with the T cell surface as judged by indirect immunofluorescence, and by its mitogenicity for quiescent peripheral blood lymphocytes. Immunohistological staining and immunoprecipitation experiments showed that both the T3-delta and T3-epsilon chains are T cell-specific. As seen with the anti-alpha/beta chain reagent WT-31, anti-T3-delta chain monoclonal antibodies stained medullary thymocytes more intensely than cortical thymocytes, whereas the difference between the staining of cortical and medullary thymocytes was generally not apparent with anti-T3-epsilon chain antibodies. Because of this specificity and their ability to react with both the denatured and the native forms of each polypeptide chain, these new monoclonal reagents will be useful tools in studies of the biosynthesis and cell surface expression of the T3/T cell receptor complex during normal and malignant thymic differentiation.     

番木瓜环斑病毒单克隆抗体的制备及在病毒分型上的初步应用

本试验是用番木瓜环斑病毒(Papaya ringspot virus, PRV)提纯制剂免疫的BALB/c小白鼠脾细胞与Sp~2/o-Ag14骨髓瘤细胞融合,获得三个能稳定传代并分泌抗番木瓜环斑病毒的单克隆抗体的杂交瘤细胞系。其中23H1 McAb的效价较高,用ELISA检测,腹水抗体效价高达1:76800,能被PRV兔抗血清所阻断。这3个杂交瘤细胞系产生的单抗与TMV和CMV无血清交叉反应。它们可把PRV四个毒株初步区分为三个血清型。     

Assessment of the specificity of a commercial human parvovirus B19 IgM assay

Background: It is important to investigate a possible cross-reaction of anti-rubella IgM in the IDEIA^™ Parvovirus B19 IgM test because many B19 infections are either asymptomatic or have clinical symptoms similar to those of rubella virus infections. Epstein-Barr virus (EBV) IgM, cytomegalovirus (CMV) IgM, measles IgM and rheumatoid factor (RF) IgM cross-reactions were also studied.Objectives: In the period from February to September 1994 (including a parvovirus B19 epidemic) more than 10 000 serum samples were examined for parvovirus B19 IgM in Denmark. This gave an opportunity to evaluate the commercial IDEIA^™ Parvovirus B19 ELISA kit (DAKO A/S, Glostrup, Denmark), which was used routinely at Statens Serum Institut from the beginning of 1994 and onwards.Study design: A total of 123 parvovirus B19 IgM positive sera were tested for reactivity in rubella IgM EIA. A total of 78 rubella IgM positive sera, 60 EBV VCA-IgM positive sera, 30 CMV IgM positive sera and 24 measles virus IgM positive sera were tested for reaction in IDEIA^™ Parvovirus B19 IgM test. Finally, 25 parvovirus IgM positive sera were tested for specific IgM against measles virus, EBV (VCA), CMV and for RF.Results: One anti-B19 IgM positive serum sample reacted positively in the rubella IgM test. Of rubella IgM positive serum samples 4% cross-reacted in IDEIA^™ Parvovirus B19 IgM test, as did 17 and 20% of EBV VCA-IgM and CMV IgM positive serum samples respectively. None of measles virus IgM positive serum samples cross-reacted in the IDEIA^™ Parvovirus B19 IgM test. Of 25 initially parvovirus B19 IgM positive sera 20% cross-reacted in EBV VCA IgM test and 8% in the CMV IgM test. None reacted positively in measles virus IgM test; 28% showed weak reactivity in RF IgM test.Conclusions: Precautions must be taken when results of IgM assays are interpreted. Epidemiological and clinical observations must be considered.     

Coxsackie B virus infection and β cell autoantibodies in newly diagnosed IDDM adult patients

Background: Environmental agents such as viruses have been identified as potentially important determinants of insulin-dependent diabetes mellitus (IDDM). Enterovirus infections, Coxsackievirus B especially, could be linked to the β cell damaging process and to the onset of clinical IDDM.Objectives: Enteroviral (EV) infection and β cell autoimmunity were studied in adult patients at the onset of IDDM.Study design: A total of 14 newly diagnosed-IDDM patients with ketosis or ketoacidosis were compared to, anteriorly diagnosed IDDM patients with metabolic decompensation, non-IDDM patients with metabolic decompensation and healthy adults. EV infection was studied by genomic RNA detection in whole blood using a RT-PCR assay. In order to assess the level of β cell autoantibodies at the time of the initial metabolic decompensation, serum specimens from IDDM patients were tested for GAD65 antibodies and islet cell antibodies (ICAs).Results: Coxsackie B3 or B4 virus genome was detected and genotyped in five of 14 (35.7%) newly diagnosed IDDM patients and in one of 12 (8%) patients in the course of IDDM. By contrast, none of the 12 non-IDDM patients and none of the 15 healthy adults was positive for enterovirus RNA detection in whole blood. Positive GAD65 antibodies and ICAs assays were not significantly correlated to a positive EV-RNA detection.Conclusion: The present study demonstrates that Coxsackie B virus RNA sequences can be detected in the peripheral blood from adult patients at the onset or in the course of IDDM and suggests that a Coxsackie B virus infection could initiate or accelerate β cell autoimmune damaging process.     

Identification of cell subpopulations by dual-color surface immunofluorescence using biotinylated and unlabeled monoclonal antibodies

A new method of dual-color immunofluorescence is presented for analysis of surface antigen distribution among heterogeneous cell suspensions. It involves flow cytometric analysis of cells stained with a biotinylated first monoclonal antibody and/or with an unlabeled second monoclonal antibody. After addition of streptavidin-phycoerythrin and/or fluoresceinated goat antimouse immunoglobulin antibody, single-cell fluorescence intensities are measured and biparametric graphic representations are obtained, allowing one to determine the percentage of cells stained by each of the monoclonal antibodies or both. The validity of the method was assessed on human peripheral blood mononuclear cells by using three sets of two monoclonal antibodies: CD8 and CD5, CD3 and CD4, CD11 and HLA-DR. The results showed that dual staining did not induce significant quenching or competition between pairs of antibodies. The procedure is simple and sensitive. It requires only minute amounts of monoclonal antibodies. It is readily applicable to the screening of hybridoma supernatants and to the characterization of new antibodies to cell surface antigens with respect to well-defined markers.     

Human eosinophils express CR1 and CR3 complement receptors for cleavage fragments of C3

The functional and antigenic characteristics of C3 receptors expressed on human eosinophils were investigated using rosette assays with sheep erythrocytes coated with C3 fragments and flow cytometric analysis of cells stained with anti-receptor antibodies. Purified peripheral blood eosinophils from 13 patients with hypereosinophilia expressed CR1 antigens. In 8 patients, a mean of 14 + 9.5% eosinophils formed C3b-dependent rosettes that were inhibited by F(ab')2 anti-CR1 antibodies. This number increased to 33% following stimulation with leukotriene B4 (LTB4) (10(-7) M). Similar numbers of C3b rosettes were formed by hypodense and normodense eosinophils. Eosinophils from 2 patients from this group expressed 20,000 125I-labeled monoclonal anti-CR1 antibody binding sites/cell. In another group of patients, 55 +/- 9% eosinophils spontaneously formed C3b-dependent rosettes that could not be enhanced by LTB4. In all patients, a mean of 16 +/- 9% eosinophils formed cation-dependent rosettes with C3bi-bearing intermediates that were inhibited by anti-CR3 antibody OKM1. All eosinophils stained with monoclonal antibodies against the alpha chain of CR3. There was no C3d-dependent rosette formation with eosinophils and no eosinophils stained with monoclonal anti-CR2 antibody. Thus, human eosinophils express CR1 and CR3. Since CR3 is required for the adhesion of granulocytes to surfaces and antibody-dependent cellular cytotoxicity of neutrophils, the interaction of C3 fragments with CR3 and CR1 on eosinophils may be of importance in eosinophil-mediated damage of opsonized targets.