title: Flow cytometry analysis of OKT4 epitope deficiency in South African black children.
abstract: A case of OKT4 epitope deficiency referred for investigation with suspected immunodeficiency is described. Flow cytometry analysis of OKT4 epitope deficiency in a study group of healthy black children showed different manifestations of the lack of OKT4 epitope; a complete lack of OKT4+CD4+ peripheral blood lymphocytes (PBL) with normal numbers of OKT4A+ and Leu3a-CD4+ PBL, decreased percentage OKT4+CD4+ compared with OKT4A+ and Leu-3a+CD4+ PBL, decreased fluorescent staining intensity with OKT4 and a biphasic OKT4 staining pattern associated with a reduced OKT4/Leu-3a ratio. The percentage and fluorescent intensity of OKT4+CD4+ PBL in the study group were significantly lower (P < 0.0001) than Leu-3a+CD4+ and OKT4A+CD4+ PBL. There is thus considerable risk of under-estimating the number of CD4+ cells in black South Africans if the OKT4 MoAb is used.
authors.affiliation: Department of Paediatrics and Child Health, Institute of Child Health, Rondebosch, South Africa.
authors.forename: E J
authors.initials: EJ
authors.lastname: Hughes
authors.forename: E A
authors.initials: EA
authors.lastname: Goddard
authors.forename: P
authors.initials: P
authors.lastname: Bouic
authors.forename: D W
authors.initials: DW
authors.lastname: Beatty
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000032:analysis* / Q000276:immunology*; D044383:Black People / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000032:analysis* / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000453:epidemiology / Q000235:genetics / Q000276:immunology*; D007223:Infant; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D018655:Lymphocyte Count; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology; D013019:South Africa / Q000453:epidemiology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D010835:Phytohemagglutinins; D015759:Ionomycin