Recently activated naive CD4 T cells can help resting B cells, and can produce sufficient autocrine IL-4 to drive differentiation to secretion of T helper 2-type cytokines.

摘要: Development of T cells during primary responses was investigated using pigeon cytochrome C-specific naive Th from TCR transgenic mice. Naive CD4 did not activate and help resting B cells. This failure found to be primarily because the were incapable stimulating Th. Provision a costimulatory signal such as anti-CD28, or addition APCs that express molecules, dendritic cells, activated B7+ B7+ICAM(+)-expressing fibroblasts, induced activation promoted cell-dependent for IgM secretion. cell little 24 h helper activity, Ig secretion required production small amounts IL-4 by On initial stimulation, secrete only IL-2. By mRNA analysis, also shown produce IL-4, however induction message occurred after additional stimulation with Ag. A single exposure Ag/APC followed 4 12 days in culture led generation effector which secreted IL-2 some IFN-gamma, no detectable IL-5, could In contrast, similar cultures received one more times this period generated capable secreting easily titers well able now promote IgG1 IgE responses. Generation these Th0-like effectors accompanied increasing each restimulation, anti-IL-4 inhibited development capacity Th2 cytokines. These studies reinforce notion must interact professional APC, rather than cell, initiation response, but show an interaction can result rapid ability provide cognate They suggest if receive multiple stimulations Ag/APC, enough endogenous produced drive differentiation into type 2 The existence autocrine feedback mechanism suggests amount availability Ag influence nature polarization response.