Systemic lupus erythematosus with deficiency of the T4 epitope on T4 helper/inducer cells

Flow cytometry analysis of OKT4 epitope deficiency in South African black children

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.

Lack of Leu-3a epitope on T-helper (CD4) lymphocytes

Human T-helper cells express membrane-bound CD4 antigen whose many epitopes are recognized by different monoclonal antibodies. The epitope recognized by Leu-3a and similar clones has been shown to be the location for human immunodeficiency virus (HIV) receptor. We have found a unique blood donor whose CD4+ T-helper lymphocytes were lacking Leu-3a epitope. CD4+ T-helper cells lacking Leu-3a epitope might be resistant to HIV infection.

The influence of age, race, and gender on peripheral blood mononuclear-cell subsets in healthy nonsmokers

To investigate the influence of age, race, and gender on the cellular immune system, we determined T-cell, B-cell, monocyte, natural killer (NK)-cell, and HLA-DR+-cell subsets in 266 nonsmokers from a population-based random sample of healthy adults using monoclonal antibodies and flow cytometry. Blacks had a lower total white blood-cell count than whites (P less than or equal to 0.0001), due primarily to a decrease in granulocytes. There was no significant difference in absolute lymphocyte count between blacks and whites. Blacks had a higher proportion of CD19+ cells (Leu 12+ B cells) and a lower proportion of CD3+ cells (OKT3+ T cells) than whites (P less than or equal to 0.01). Female sex and increasing age were independently associated with an increased percentage of CD4+ cells (OKT4A+ helper-inducer T-cell subset), resulting in a higher helper/suppressor ratio among women and older individuals (P less than or equal to 0.05). Black race and increasing age were independently associated with an increased proportion of HLA-DR+ cells (P less than or equal to 0.0001) which was not attributable to B cells or monocytes. No significant age, race, or gender effects were observed for CD14+ cells (Leu M3+ monocytes) or CD16+ cells (Leu 11A+ natural killer cells). These data demonstrate that age, race, and gender are each associated with significant differences in peripheral blood mononuclear-cell subsets. Population-based data such as these provide an important foundation for future design and interpretation of human flow cytometry data.

Functional properties of neoplastic T cells in helper T cell prolymphocytic leukaemia with IgM hypergammaglobulinaemia

A case of T cell prolymphocytic leukaemia of helper/inducer T cell phenotype with IgM hypergammaglobulinaemia in a 65-year-old Saudi man is presented. The neoplastic T cells in the patient had an OKT3+, OKT4+, OKT8-, OKT11+, OKCLL+, OKIa1+, OKDR+, Tac+ phenotype. The presence of OKIa1+, OKDR+, and Tac+ antigens indicates that the leukaemic T cells were in an activated state. The cells responded to phytohaemagglutinin, but showed a diminished response to concanavalin A. The reduced interleukin 2 receptor expression and interleukin 2 production were associated with defective concanavalin A-induced proliferation. There was suppression of mixed lymphocyte culture reaction between the patient and two healthy donors in response to concanavalin A. In vitro immunoglobulin production experiments demonstrate that the leukaemic T cells provided an enhanced helper cell function to produce IgM, and suppressor cell function to produce IgG immunoglobulins by pokeweed mitogen-induced normal B lymphocyte differentiation. In this study we also found that the patient's T cells proliferate in response to lipopolysaccharides, thus providing the first evidence that leukaemic (OKT4+) T cells from a prolymphocytic leukaemia patient can be stimulated by lipopolysaccharides.