Molecular and functional characterization of chicken IL-15

A cDNA encoding chicken interleukin-15 was cloned from a CD4(+) T cell hybr idoma expression library by screening with a rabbit antibody against a prot ein fraction of conditioned medium containing T cell growth promoting activ ity. The chicken IL-15 cDNA contains an open reading frame of 143 amino aci ds with a single potential N-linked glycosylation site. The predicted m.w. of the encoded protein (16 kDa) matched the size of an immunoreactive band on Western blots of E. coli expressing the recombinant IL-15. Amino acid an d nucleotide sequence analyses of chicken IL-15 revealed 31% and 46% identi ty with bovine IL-15 respectively and lesser homologies to other mammalian IL-15s. Chicken IL-15 contained all 4 highly conserved cysteine residues pr esent in mammalian IL-15 sequences. RT-PCR demonstrated that the chicken IL -15 gene is expressed in many tissues including spleen, intestine, and musc le and in established macrophage. T lymphoma and fibroblast cell lines. Act ivation of spleen cells with Con A enhanced the expression of IL-15 gene tr anscripts in a time-dependent manner. CHO-KI cells transfected with the chi cken IL-15 cDNA secreted a biologically active protein supporting the growt h of Con A activated spleen lymphocytes. Continuous culture of spleen Con A lymphoblasts with chicken IL-15 over two months resulted in an enriched T lymphocyte population expressing the gamma delta TCR, CD8 alpha, and CD3 ce ll surface antigens. Published by Elsevier Science Ltd.