Role of lymphocytes and cytokines in sympathetic innervation of spleen: A study using immunodeficient mice

Abstract

To investigate the role of lymphocytes and cytokines in neuritogenesis of sympathetic neurons induced by lymphoid tissues, we performed immunochemical studies in spleen of wild-type and C.B-17 SCID (T and B cell deficient) mice, using antibodies against tyrosine hydroxylase (TH) and nerve growth factor (NGF). In SCID mice, TH-positive fibers were significantly sparse in parenchymal fields of lymphocytes, but not altered around vasculature in white pulp, compared to wild-type mice. On the contrary, NGF-positive cells were found to be abundant in the lymphoid fields of SCID mice. Reconstitution with wild-type splenic lymphocytes significantly increased TH-positive fibers in the splenic lymphoid fields of SCID mice 3 weeks after the lymphocyte injection. ELISA showed that the splenic level of IL-1 was significantly more in SCID mice than wild-type mice. The IL-6 level was not significantly different between these mice. These studies suggest that lymphocytes are essential to promote neuritogenesis of sympathetic neurons in lymphoid tissues, which may be mediated by a cytokine different from NGF, IL-1 or IL-6. [Jpn J Physiol 54 Suppl:S196 (2004)]