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.