In vitro evaluation of cell-mediated immunity in mice: experiments with soluble and cellular antigens in a spleen-thymus cell leucocyte migration test (LMT).

A modification of the macrophage or leucocyte migration inhibition assay usable in a murine model has been developed. The system operates with mixed spleen–thymus cell populations from mice sensitized to soluble protein or to transplantation antigens. In order to obtain significant inhibition it was found necessary to preincubate the sensitized cells with specific antigen for 24 hr prior to the migration assay. The macrophage inhibitory factor (MIF) has been found to determine the rate of migration inhibition in the mouse system whereas the role of humoral antibody is negligible. The murine MIF is not strain specific and operates in the absence of specific antigen. Spleen–thymus cells from St/a mice sensitized to a first set C3H skin allograft were inhibited by approximately 30% while cells sensitized to a second set graft showed a 50% inhibition when migrating against C3H cells or MIF produced by confrontation between sensitized St/a lymphoid cells and C3H antigen.