Yes T cells, but three different T cells (alpha beta, gamma delta and NK Tcells), and also B-1 cells mediate contact sensitivity

Transfer of contact sensitivity (CS) responses by immune lymphoid cells was the first finding that distinguished cellular from humoral immunity. CS ha s remained the most studied T cell reaction in vivo, and is the prototype f or a variety of delayed-type hypersensitivity (DTH) responses. DTH in essen ce is the recruitment of effector alpha beta -T cells out of vessels into p eripheral tissues. The T cells then are activated by antigen presenting cel ls to produce pro-inflammatory cytokines. It has been assumed that the alph a beta -T cells alone are responsible, but recent studies show that three o ther lymphocyte subsets are involved: CS-inducing NK T cells, CS-initiating B-1 cells, and CS-assisting gamma delta -T cells. Therefore, the effector alpha beta -T cells are essential, but cannot be recruited into the tissues without the local action of IgM antibodies produced by B-1 cells rapidly ( 1 day) post-immunization. The IgM complexes with the challenge antigen to l ocally activate complement to lead to vascular activation required for T ce ll recruitment. This process occurs early (1-2 hours) in the elicitation ph ase, and is called CS-initiation. The essential CS-inducing NK T cells acti vate the B-1 cells by producing IL-4 rapidly (1 hour) after immunization, a nd gamma delta -T cells assist the local inflammatory function of the recru ited CS-effector alpha beta -T cells. Thus, four lymphocyte subsets are req uired for elicitation of responses: CS-inducing NK T cells, CS-initiating B -1 cells, CS-assisting gamma delta -T cells, and finally the CS-effector al pha beta -T cells. Three of these four cell types are present in the immune lymphoid cell population that adoptively transfers CS: B-1 cells, gamma de lta -T cells, and the alpha beta -T cells.