Membrane-associated interleukin 1 is required for the activation of T cells in the anti-CD3 antibody-induced T cell response.

To establish the role of the membrane-associated form of IL 1 in T cell activation, we tested the accessory function of monocytes (Mo) that were unable to secrete or release soluble IL 1. The data obtained show that strictly purified resting T cells start to proliferate in response to anti-CD3 antibody (OKT3) stimulation in the presence of paraformaldehyde (PFA)-fixed Mo or 3-day cultured Mo (macrophages). The findings that i) PFA-fixed Mo did not produce or release IL 1, ii) the accessory function of PFA-fixed Mo could be inhibited with pretreatment with anti-IL 1 antibody, iii) PFA-fixed Mo had a comitogenic effect in the murine thymocyte assay, and iv) there was a temporal difference between the capacities to function in the comitogenic assay and to produce soluble IL 1, suggest that human Mo can express membrane-associated IL 1 and that it is functionally relevant.