title: Helper activity for immunoglobulin synthesis of T helper type 1 (Th1) and Th2 human T cell clones: the help of Th1 clones is limited by their cytolytic capacity.
abstract: A large number of CD4+ human T helper type 1 (Th1) clones specific for purified protein derivative and of Th2 clones specific for the excretory/secretory antigen of Toxocara canis, derived from the same individuals, were analyzed for both cytotoxic capacity and helper function for immunoglobulin (Ig) synthesis. The great majority of Th1, but only a minority of Th2 clones exhibited cytolytic activity. All Th2 (noncytolytic) clones induced IgM, IgG, IgA, and IgE synthesis by autologous B cells in the presence of the specific antigen, and the degree of response was proportional to the number of Th2 cells added to B cells. Under the same experimental conditions, Th1 (cytolytic) clones provided helper function for IgM, IgG, and IgA, but not IgE, synthesis with a peak response at 1:1 T/B cell ratio. At higher T/B cell ratios, a strong decrease of Ig synthesis was observed. All Th1 clones lysed Epstein-Barr virus transformed autologous B cells pulsed with the specific antigen. The decrease of Ig production at high T/B cell ratios correlated with the lytic activity of Th1 clones against autologous antigen-presenting B cell targets. These data suggest that Th1 differ from Th2 human T cell clones not only for their profile of cytokine secretion, but also for cytolytic potential and mode of help for B cell Ig synthesis.
authors.affiliation: Division of Clinical Immunology and Allergology, University of Florence, Italy.
authors.forename: G F
authors.initials: GF
authors.lastname: Del Prete
authors.forename: M
authors.initials: M
authors.lastname: De Carli
authors.forename: M
authors.initials: M
authors.lastname: Ricci
authors.forename: S
authors.initials: S
authors.lastname: Romagnani
mesh_terms: D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D015704:CD4 Antigens / Q000032:analysis; D002450:Cell Communication; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis; D007073:Immunoglobulin E / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007700:Kinetics; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007073:Immunoglobulin E