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 |
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| Authors: | G F Del Prete M De Carli M Ricci S Romagnani |
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| Affiliation: | Division of Clinical Immunology and Allergology, University of Florence, Italy. |
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| 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. |
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