Expression of L-selectin and efficient binding to high endothelial venulesdo not modulate the dissemination potential of murine B-cell lymphoma

The homing receptor L-selectin is essential for the migration of naive lymp hocytes into peripheral lymph nodes. In contrast to naive lymphocytes, acti vated and memory cells down-regulate L-selectin and enter peripheral lymph nodes by an L-selectin-independent mechanism. In view of the concept that l ymphomas present the malignant counterparts of normal lymphocytes at a defi ned stage of differentiation, it has been suggested that in contrast to lym phomas with a memory/activated cell phenotype, L-selectin is essential for dissemination of lymphomas that represent naive cells. 38C-13 is a murine B -cell lymphoma with an immature naive cell phenotype, 38C-13 cells express high levels of L-selectin and bind to lymph node high endothelial venules i n an L-selectin-dependent manner. In this study we demonstrate that treatme nt of 38C-13 tumor-bearing mice with anti-l-selectin antibodies did not inh ibit tumor dissemination to peripheral lymph nodes. Moreover, L-selectin-ne gative 38C-13 variant cells disseminated as efficiently as wild-type cells. Thus, in spite of its expression, L-selectin is not required and does not affect the metastatic potential of the tumor. L-selectin of the malignant c ells and of normal lymphocytes appears to be functionally different. Thus, whereas antibody cross-linking of L-selectin resulted in down-modulation of the receptor in normal lymphocytes, cross-linking had no effect on L-selec tin expression in 38C-13 cells, suggesting that, in spite of comparable lev els of surface expression in normal and malignant cells, L-selectin may be functionally impaired in some malignant cells.