Glomerular T-lymphocyte infiltration has recently been demonstrated to precede glomerular macrophage influx in a pre-immunized model of anti-glomerular basement-membrane antibody-induced glomerulonephritis (antiGBM-GN). In the current study, the functional role of these glomerular T-lymphocytes in directing macrophage localization was sought by measuring their production of macrophage migration inhibition factor (MIF). MIF activity in supernatants from cultured isolated glomeruli was measured in a conventional capillary tube bioassay. Glomerular T-lymphocytes (OX19 positive cells) were maximal (1.95 +/- 0.19 cells/glomerular cross section, c/gcs) 24 hours after injection of antiGBM antibody into sensitized animals. Seventy-two hours after antibody injection, T-lymphocyte numbers were reduced (1.02 +/- 0.14 c/gcs) while macrophage accumulation was maximal (at 24 hrs 4.2 +/- 1.3 macrophages/glomerulus (m/g), at 72 hrs 19.8 +/- 3.7 m/g). MIF activity was only detected in supernatants from T-lymphocyte infiltrated glomeruli (12 hrs 40.81 +/- 4.32% migration inhibition, 24 hrs 45.11 +/- 4.11% migration inhibition, 48 hrs 38.24 +/- 3.53% migration inhibition, 72 hrs 20.86 +/- 3.85% migration inhibition, all P less than 0.05). Control glomeruli from normal animals, pre-immunized animals given normal sheep globulin, pre-immunized animals given anti-GBM antibody and Cyclosporin A, and non-pre-immunized animals given antiGBM antibody did not contain glomerular T-lymphocytes, and their supernatants contained no MIF activity. This data indicates that the glomerular T-lymphocytes in pre-immunized antiGBM-GN are sensitized cells which release MIF and thus may direct glomerular macrophage localization in this model of antibody-induced glomerulonephritis.