Differential effects of CD4 and CD8 engagement on the development of cytokine profiles of murine CD4(+) and CD8(+) T lymphocytes

A simple culture system devoid of antigen-presenting cells was used to exam ine the ability of immobilized antibodies to lymphocyte function-associated antigen-1 (LFA-1) (CD11a), CD28 and CD4 or CD8 to modulate the responses o f normal murine CD4(+) and CD8(+) lymph node T cells to immobilized anti-CD 3 antibody and interleukin-2 (IL-2). All the antibodies enhanced proliferat ive responses to limiting anti-CD3 antibody. Both CD4(+) and CD8(+) cells p roduced substantial titres of IL-3 and interferon-gamma (IFN-gamma) in prim ary and secondary cultures regardless of the coactivating antibodies used f or priming. By contrast, the combination of anti-CD4 with anti-CD3 antibody stimulated significantly higher titres of IL-4 than any other antibody com bination in cultures of CD4(+) cells. This CD4-dependent IL-4 response was induced in CD4(+) T cells of naive (CD44(low)) phenotype and was similar in magnitude to the response induced by exogenous IL-4 but, unlike the latter , was not associated with elevated IL-3 synthesis. A comparable effect of a nti-CD8 antibodies on CD8(+) cells was not observed: although IL-4 producti on by CD8(+) cells was induced by exogenous IL-4, it was not detected follo wing coactivation with anti-CD8 or any other antibodies. We conclude that a nti-CD4 antibody is a potent inducer of IL-4-secreting CD4(+) T cells whose effects can be distinguished from those of anti-CD8 antibody on CD8(+) T c ells and from those of IL-4 on either subset.