The expression of the peripheral cannabinoid receptor on cells of the immune system and non-Hodgkin's lymphomas.

The peripheral cannabinoid receptor CB2 is expressed highly on normal human B-lymphocytes. C-terminal specific anti-CB2 antibody recognises a non-phosphorylated inactive receptor on naive and resting B-lymphocytes. Another, N-terminal specific CB2 antibody, primarily recognises B-cells present in the germinal centres of secondary follicles in lymph nodes. We hypothesise that N-terminal specific CB2 antibody recognises activated CB2 receptors. In this study, we showed using these antibodies, that expression of CB2 is generally absent on T-lymphocytes in reactive, non-malignant human lymphoid tissues. Applying single and dual immunohistochemistry, CD23+ follicular dendritic cells and a small but significant subpopulation of CD68+ macrophages showed positive staining with the N-terminal specific CB2 antibody but not with the C-terminal specific CB2 antibody. This may indicate the presence of an active CB2 receptor on these cells with possible involvement in immunomodulation. In contrast to the low expression...