The L-selectin antibody FMC46 mediates rapid, transient increase in intracellular calcium in human peripheral blood mononuclear cells and Daudi lymphoma cells.
We report the induction of intracellular calcium mobilization [Ca2+]i in normal peripheral blood mononuclear cells (PBMC) and Daudi cells following binding with the L-selectin monoclonal antibody FMC46. The [Ca2+]i signal was mediated directly by binding of FMC46 without cross-linking antibodies. Increased [Ca2+]i was not induced by other L-selectin antibodies tested (TQ1, Leu8, Lam1.3). The increase in [Ca2+]i was rapid and was blocked completely by BAPTA, an agent which chelates intracellular calcium. The increase in [Ca2+]i was observed in calcium-containing as well as calcium free medium, suggesting that FMC46 caused release of Ca2+ from intracellular stores. In both PBMC and Daudi cells, previous signaling via L-selectin still allowed signaling through cross-linking of surface antigen receptor. These data provide evidence for direct alteration of the state of lymphocytes after ligation of a specific L-selectin epitope. L-selectin-mediated signaling does not desensitize signaling through the antigen-receptor and could therefore play a role in preactivating lymphocytes during endothelial transmigration into lymphoid tissues.
Po
J L
JL
Royal Victoria Hospital, Department of Surgery, Montreal, Quebec, Canada.
Mazer
B
B
Jensen
G S
GS
D000911:Antibodies, Monoclonal; D002118:Calcium / Q000378:metabolism*; D002451:Cell Compartmentation; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007158:Immunologic Techniques; D019041:L-Selectin / Q000502:physiology*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D016201:Receptors, Lymphocyte Homing / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D011948:Receptors, Antigen, T-Cell; D016201:Receptors, Lymphocyte Homing; D019041:L-Selectin; D002118:Calcium