Culture-associated enhancement of LECAM-1 expression by lymphocytes and partial inhibition of enhancement by IL-4.

Recent studies have shown that the human leukocyte endothelial cell adhesion molecule-1 (LECAM-1) functions as a homing receptor, mediating leukocyte binding to high endothelial venules in peripheral lymph nodes. Increasing evidence has demonstrated that cytokines, such as IL-4, can modulate the expression of surface proteins such as homing receptors on a variety of cells. We thus investigated the modulatory effects of cytokines on LECAM-1 expression by lymphocytes using single- and dual-color flow cytometry. We found that the density of LECAM-1 expression increased markedly during 3 days of culture and that this culture-associated enhancement (CAE) of LECAM-1 expression was significantly inhibited by IL-4. B cells and both major T cell subsets (CD4, CD8) exhibited CAE of LECAM-1 expression, but the inhibitory effect of IL-4 on this response occurred only in the T cell populations. The inhibitory effect of IL-4 on enhanced LECAM-1 expression was reversible, and characterized all 3 LECAM-1 epitopes assessed. Natural killer cells, in contrast, did not exhibit CAE of LECAM-1 expression, and IL-4 had no modulatory effect on LECAM-1 expression by these cells. Another adhesion molecule, CD44, showed enhanced expression during culture, but this enhancement was not inhibited by IL-4. The results show that LECAM-1 expression by T and B lymphocytes is significantly increased during culture and that the inhibitory effect of IL-4 on this increase is restricted to T cells. These findings suggest that IL-4, generated during an immune response, may play a role in regulating the migration and localization of T lymphocytes to lymphoid tissues.