(TGF- 1): Molecular cloning, tissue distribution and immunobiological activity in teleost peripheral blood lymphocytes

Transforming growth factor1 (TGF1) is a potent regulatory cytokine with pleiotropic effects on the immune system. To examine the role of TGF1 in fish immunity, the full-length cDNA of grass carp TGF1 was isolated from grass carp spleen. The open reading frame of grass carp TGF1, 1134 bp in length, encodes a 377 amino acid protein. Tissue distribution study by RT-PCR showed TGF1 mRNA was predominantly expressed in the thymus, head kidney and spleen in grass carp tissues. Moreover, the time-course effect of TGF1 on peripheral blood lymphocyte proliferation in response to mitogens was evaluated in grass carp. Interestingly, TGF1 induced PBL proliferation while it significantly blocked phytohemagglutininor lipopolysaccharide-stimulated PBL proliferation, and TGF1 mimicked the stimulatory effects of lipopolysaccharide on grass carp MHC I mRNA expression. These results, for the first time, strongly suggest that TGF1 plays a functional role in lymphocyte proliferation in fish. © 2007 Elsevier Ltd. All rights reserved.