Characterization of a novel subset of T cells from human spleen that lacks L-selectin.

Human L-selection (LAM-1, Leu-8, TQ1, DREG 56) is a member of the 'selection' family of adhesion molecules. Antibodies to L-selectin have been shown to block the binding of T cells to peripheral lymph node high endothelial venules (HEV). Most unstimulated peripheral blood T cells express high levels of L-selectin whilst it is only weakly expressed on the majority of T cells from secondary lymphoid organs. We show here (a) that T cells from tonsil and lymph node up-regulate L-selectin when released from their microenvironment, (b) that in contrast, spleen contains a stable L-selectin negative subset, (c) that this subset remains surface L-selection negative after stimulation even though the T cells can respond by proliferation, (d) that this subset expresses minimal levels of LAM-1 mRNA and (e) that mucosal lymphocyte antigen (MLA) positive and T-cell receptor (TcR) gamma delta positive T cells found within the L-selectin negative population are similar to subsets of T cells found amongst lamina propria (LP) and intraepithelial lymphocytes (IEL) of the gut.