Identification d'un nouveau mécanisme de régulation négative de la réponse lymphocytaire T CD4+

Although T cells proliferate extensively during an immune response, they don't expand indefinitely. The mechanisms limiting the expansion are poorly understood, though the disappearance of antigen, or competition for limiting amounts of antigen, have been suggested. During my PhD, I studied the recruitment of antigen-experienced CD4 T cells into a localized immune response. We found that the recruitment of antigen experienced T cells is selectively inhibited compared to that of naive T cells. This preferential inhibition begins as soon as day 2 of the immune response and takes place before antigen disappearance. Importantly, this inhibition is antigen specifie and relies on the presence of responding T cells that present MHCII/peptide complexes captured from their antigen presenting cells early in the response. This inhibition of antigen-experienced CD4 T cells proliferation by MHCII/peptide bearing T cells generates a negative feedback loop that regulates CD4 T cell proliferation.