Question

Are the apc produce cytokine to convert naive t cell to th1 or 2 , or the naive tcell produce cytokine to convert another naive to t cell .. another question , sometime toll like receptor join to mhc and sometime tcr join mhc !!!

Answer 1

Antigen presentation by APC (antigen presenting cell) stimulates naive CD4+ T cells (TH0) to become mature "helper" CD4+ cells (TH1 and TH2). APCs such as macrophages and dendritic cells produce cytokines (mainly IL-12 and IL-10) that contribute to the preferential expansion of TH1- or TH2-type cells.

APCs produce cytokine to convert naive T-cell to TH1 or 2.

Naive T-cells do not convert another naive T-cell to helper cells 1 or 2.

Yes, Toll like receptor (TLR) joins MHC II to mediate innate immunity while T-cell receptor (TCR) joins MHC II for effective adaptive immune response.