The expressions and cellular distributions of two pairs of adhesion molecules CD2/LFA-3 (leukocyte function-associated antigen-3) and LFA-1/ICAM-1 (intercellular adhesion molecule-1) were examined in inflammatory cellular infiltrates of advanced squamous cell carcinomas of the head and neck by immunohistochemical techniques including double-staining methods. Thirteen patients were investigated using the following monoclonal antibodies (mAbs): CD2, LFA-3 (CD58), ICAM-1 (CD54), LFA-1 (CD11a), the alpha/beta and gamma/delta T-cell receptor, pan T cells and broadly distributed monocyte/macrophage (m/m phi) [Fc gamma RII (CD32), 25F9, RM3/1]. LFA-3 staining was observed on a high number of cells (968 +/- 112 cells/mm2), correlating to the number of Fc gamma RII (CD32; P < 0.01), 25F9 (P < 0.05) and RM3/1 (P < 0.05) positive m/m phi. Its ligand CD2 was found on 365 +/- 126 cells/mm2, representing about 50% of CD3+ cells (730 +/- 286 cells/mm2). CD2 positivity correlated to CD3 and CD8 (P < 0.01) but not to CD4+ T cells. LFA-1 and ICAM-1 were expressed on lymphocytes as well as on m/m phi. ICAM-1+ cells (902 +/- 205 cells/mm2) correlated to CD3+, CD8+ and RM3/1+ cells (P < 0.01). LFA-1 positivity (803 +/- 255 cells/mm2) showed correlations to nearly all investigated antigens, as well as to CD4+ T cells (P < 0.05). These results show that different m/m phi subsets display distinct patterns of adhesion molecule expressions suggesting different pathways of regulation. The CD3+ lymphocyte population revealed a lack of CD2 expression that was more pronounced in the CD4+ subset and indicated impaired lymphocyte function.