We investigated whether the sensory neuropeptide, calcitonin gene-related peptide (CGRP), could be synthesised by human lymphocytes. Our results indicate that in activated B-cells, there is a strong expression of CGRP gene transcripts, which is almost absent in resting cells. Since B-cells autocrinally produce NGF, the neutralisation of endogenous NGF by anti-NGF antibodies resulted in a marked reduction in CGRP expression in both resting and activated B-cells. Thus, NGF appears to directly affect the synthesis of CGRP in B-cells as in sensory neurons. By regulating CGRP synthesis in lymphocytes and neuronal cells, NGF can influence the intensity and duration of the immune response.