Immunoregulatory roles of interleukin-13 in cattle

Interleukin-13 (IL-13) is produced predominantly by helper T lymphocytes of the Th2 phenotype and mediates its effects on several immune cells, includ ing B lymphocytes and macrophages, stimulating their proliferation, differe ntiation, and effector functions. IL-13 activates human B cells but has no detectable activity on murine B lymphocytes, suggesting that the activity o f IL-13 varies among species. Our studies show that IL-13 enhances prolifer ation and differentiation of bovine B cells and upregulates cell surface ma jor histocompatibility complex (MHC) class II expression. We examined mRNA expression of the putative signaling component of the bovine IL-13R alpha 1 homolog in several peripheral blood populations. After stimulation with ca lcium ionophore and phorbol ester, IL-13R alpha 1 mRNA levels appeared to b e downmodulated in T cells, upregulated in macrophages and B cells, and unc hanged in neutrophils, Together, these studies begin to provide insight int o the relative importance of IL-13 in immunoregulation in cattle.