REGULATION OF CYTOKINE EXPRESSION IN MACROPHAGES AND THE LANGERHANS CELL-LIKE LINE XS52 BY CALCITONIN-GENE-RELATED PEPTIDE

Calcitonin gene-related peptide (CGRP) inhibits antigen presentation b y Langerhans cells (LC) and macrophages, and LC are anatomically assoc iated with CGRP-containing epidermal nerves. To determine whether CGRP may produce some of its functional effects through regulation of cyto kine expression, we utilized enzyme-linked immunosorbent assay (ELISA) of conditioned supernatants to examine production of interleukin (IL) -10 and IL-1 beta protein in the LC-like cell line XS52 as well as the reverse transcriptase-polymerase chain reaction (RT-PCR) to examine l evels of mRNA for IL-10, IL-1 beta, and the 4O-kDa subunit (p40) of IL -12. CGRP augmented the lipopolysaccharide (LPS) and granulocyte-macro phage colony-stimulating factor (GM-CSF)-induced release of IL-10 prot ein and the induced expression of IL-10 mRNA in these cells. However, it suppressed the induction of release of IL-1 beta protein and the in duction of mRNA for IL-12 p40 and IL-1 beta by LPS and GM-CSF. Regulat ion of cytokine expression in peritoneal macrophages was also examined . By ELISA, the LPS-induced expression of IL-10 was augmented by CGRP, whereas the induction of IL-1 beta was suppressed. Northern analysis demonstrated augmentation of LPS-induced IL-10 mRNA levels and inhibit ion of LPS-induced IL-1 beta mRNA by CGRP. CGRP inhibited the LPS-indu ced induction of IL-12 mRNA as assessed by RT-PCR. Upregulation of B7- 2 expression by LPS and GM-CSF was suppressed by CGRP in both XS52 cel ls and macrophages, as preciously reported. This suppression, however could be abrogated by co-culture with neutralizing antibodies to IL-10 . Furthermore, the presence of neutralizing antibodies to IL-10 during exposure of epidermal cells (EC) to CGRP prevented the CGRP-mediated suppression of EC presentation of tumor-associated antigens (from the S1509a spindle cell carcinoma) for elicitation of delayed-type hyperse nsitivity in S1509a-immune mice. These data suggest that suppression o f antigen-presenting function by CGRP is mediated, at least in part, b y changes in cytokine expression that favor less robust antigen presen tation for cell-mediated immunity.