The effect of chemokine CCL19 on B lymphocytes /

B-T lymphocyte interaction within lymphoid tissues following antigen exposure is a crucial step in the generation of high affinity antibody. Due to its expression pattern and specificity for B lymphocytes, CC Chemokine Ligand 19 (CCL19) may help initiate the adaptive humoral immune response following antigen exposure. Here we show CCL 19 induced [Ca2+]i mobilization, chemotaxis and rescue from apoptosis in B lymphocytes. Because CCL19 is constitutively expressed, we studied the expression and signalling properties of its corresponding chemokine receptor, CC chemokine receptor 7 (CCR7) in various B cell populations. We found that CCL19 responsive CCR7 + cells belonged to distinct B lymphocyte populations at particular stages of maturation and that BCR crosslinking alone was insufficient to modulate CCR7 expression and CCL19 responsiveness. CCL19 induced signal transduction events were Galphai dependent. We found that CCL19 stimulation could desensitize the CCR7 receptor to further CCL19 stimulation, but did not interfere with other key B cell activation signals such as BCR and PAF. Our results implicate CCL19 in B lymphocyte activation, migration, and survival