Detection of surface and cytoplasmic CD4 on blood monocytes from normal and HIV-1 infected individuals.
CD4 on blood monocytes is generally regarded as being found on a subset of blood monocytes. However, our results show that all monocytes are CD4+ but the number of molecules per cell is lower than T cells. We have performed immunofluorescent (flow cytometry, microscopy) analysis of monocytes from normal donors and HIV-1-infected patients using anti-CD4 (Leu-3a) and the monocyte-specific marker anti-CD14 (Leu-M3) monoclonal antibodies. Specifically: (1) 91% of monocytes from normal individuals show dual positivity for CD14 and CD4 (n = 14) as measured by flow cytometry; (2) 76% of monocytes expressed surface bound CD4 and CD14 when an enhanced two colour immunofluorescence microscopic technique was employed; (3) all CD14+ monocytes stained with an intensity of 3+(-)4+ for cytoplasmic CD4. Few monocytes were CD14- and CD4+. Cell surface CD4 expression was blocked with unconjugated anti-CD4 prior to staining; (4) the staining intensity for cytoplasmic CD4 in T cells was negligible; (5) CD4 expression on monocytes obtained from patients was as observed with normal individuals. The conclusion drawn is that all monocytes are CD4+ and the CD4 expression in monocytes is mainly cytoplasmic. Thus, all monocytes are potentially infectable with HIV-1.
Department of Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ontario, Canada.
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Izaguirre
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Garber
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D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis*; D015704:CD4 Antigens / Q000032:analysis*; D003593:Cytoplasm / Q000276:immunology*; D005434:Flow Cytometry; D015497:HIV-1; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D018950:Lipopolysaccharide Receptors; D008856:Microscopy, Fluorescence; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D015214:Antigens, Differentiation, Myelomonocytic; D000954:Antigens, Surface; D015704:CD4 Antigens; D018950:Lipopolysaccharide Receptors