title: A false expression of CD8 antigens on CD4+ T cells in a routine flow cytometry analysis.
abstract: The two-colour flow cytometry method applied in a routine enumeration of peripheral blood T lymphocyte subsets reveals that in some patients the entire population of CD4+ lymphocytes seems to express CD8 determinants as well. However, expression of the CD8 antigens on the cell surface is much lower in comparison with typical CD8+ cells. Moreover, in one-colour staining with an anti-CD8 antibody, cells with weak CD8 expression are not observed and only one typical population of CD8+ lymphocytes is seen. Investigating this phenomenon, we showed that after washing patient cells in RPMI before CD4/CD8 staining, the CD4+ T cell population did not show CD8 "co-expression". These results suggest that CD4+ lymphocytes, which seem to co-express CD8 antigen, in fact do not have this antigen on their surface. Moreover, after the addition of patient plasma to healthy donor cells prior to CD4/CD8 staining, a weak CD8 expression on normal CD4+ cells was noticed. Therefore we can assume that the agent(s) causing this phenomenon is/are present in the plasma of some patients. Altogether, these observations suggest that this phenomenon is nonspecific and probably results from cross-linking of anti-CD8 mAbs with anti-CD4 mAbs caused by factor(s) present in plasma of some patient. However, identification of that/these factor(s) requires further research.
authors.affiliation: Department of Clinical Immunology, Polish-American Institute of Pediatrics, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Bukowska-Straková
authors.forename: Jarosław
authors.initials: J
authors.lastname: Baran
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Gawlicka
authors.forename: Danuta
authors.initials: D
authors.lastname: Kowalczyk
mesh_terms: D000328:Adult; D018791:CD4 Lymphocyte Count / Q000379:methods; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D016827:CD8 Antigens / Q000378:metabolism*; D002648:Child; D005189:False Positive Reactions; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008297:Male
chemical_list: D016827:CD8 Antigens