title: CD4+CD57+ T cells derived from peripheral blood do not support immunoglobulin production by B cells.
abstract: A small subpopulation of CD4+ T cells found in peripheral blood coexpresses the CD57+ marker normally found on, e.g., NK cells. It is known that this population occurs in a higher frequency in certain diseases. The same antigen has also been shown to be expressed on CD4+ T cells derived from germinal centers. The localization of this cell population to specialized lymphoid structures suggests that it may play a role in the evolution of the antibody response following antigenic stimulation in vivo. We have examined the ability of peripheral blood helper T cells coexpressing CD57 to participate in B cell activation/differentiation and evaluated their responses to polyclonal stimulation. The CD4+CD57+ T cells do not express mRNA for a number of different cytokines or for the CD40 ligand after activation in vitro. Furthermore these cells do not induce differentiation of B cells into immunoglobulin-producing cells. Consequently, despite their CD4 phenotype and their ability to be activated, to express the IL-2 receptor, and to enter into the cell cycle, they do not act as T helper cells under conditions where CD4+/CD57- cells normally do so. The findings suggest that this peripheral blood helper T cell population is functionally different from regular CD4+ T cells. The basis for the lack of proper costimulatory signals for immunoglobulin production might be related to the low expression of CD28.
authors.affiliation: Department of Immunotechnology, Lund University, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Andersson
authors.forename: M
authors.initials: M
authors.lastname: Ohlin
authors.forename: C A
authors.initials: CA
authors.lastname: Borrebaeck
authors.forename: R
authors.initials: R
authors.lastname: Carlsson
mesh_terms: D015703:Antigens, CD / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D018106:CD28 Antigens / Q000096:biosynthesis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018959:CD57 Antigens; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation / Q000276:immunology; D008222:Lymphokines / Q000502:physiology; D008969:Molecular Sequence Data; D010641:Phenotype; D013601:T-Lymphocytes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D018959:CD57 Antigens; D007136:Immunoglobulins; D008222:Lymphokines