Leucocyte interaction with other cells is facilitated by the adhesion molecules, leucocyte function-associated antigen-1 (LFA-1)-binding to intercellular adhesion molecule-1 (ICAM-1) and for T cells and natural killer (NK) cells the binding of LFA-2 (CD2) to LFA-3. As these interactions are critical for the mediation of graft destruction by effector T cells, we examined whether there was a change in the expression of these molecules during rejection compared to normal kidneys. In normal kidneys, peritubular and glomerular capillaries and large vessel endothelium expressed ICAM-1 and LFA-3, but tubular cells expressed only low levels of LFA-3. LFA-1-expressing cells, which were probably macrophages, were observed in the glomerulus. A few scattered LFA-1-expressing cells in the interstitium were probably tissue macrophages or dendritic cells, and only occasional interstitial mononuclear cells expressed LFA-2. During rejection, there was an infiltrate of mononuclear cells expressing LFA-1 and the T cell and NK cell component of the infiltrate expressed LFA-2. Neither of these markers was expressed by kidney parenchymal cells except for one allograft with severe rejection which showed LFA-1 beta chain expression by some tubular cells. Tubular cells had increased expression of ICAM-1 during rejection but there was no increase in LFA-3. The importance of LFA-2 and ICAM-1 expression on kidney tubular cells for adhesion of activated T cells was also examined in an in vitro system.(ABSTRACT TRUNCATED AT 250 WORDS)