Submitted to: Cytokine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 1997
Publication Date: N/A
Interpretive Summary: Studies aimed at defining the role of cytokines in the generation of protective immune responses to infectious diseases of cattle have been hampered by the lack of specific bovine reagents. Il-15 is a newly identified growth factor that shares many of the activities of the IL-2, in addition recent studies suggested it may play an important role in the initial stages of the immune response to infection. In this manuscript we have cloned, expressed and purified the bovine IL-15. We have produced a competitor molecule to be use in quantification studies, and showed constitutive levels of IL-15 within a broad range of tissues and cell types, and we have determined that IL-15 transcription could be down-regulated in the presence of low concentrations of IL-2. The availability of these reagents will allow the investigation of the role of this cytokine in the responses against infectious diseases of cattle.
The bovine IL-15 sequence was cloned from abomasal lymph node mRNA by enzymatic amplification of cDNA using human primers proximal to and including the translation start and stop sites. The open reading frame is 486 base pairs in length and the proposed protein sequence shows 78.4% and 73.5% similarity with that predicted for the human and mouse sequences, respectively. Expressed and purified recombinant bovine IL-15 in the absence of the 48-amino acid leader sequence stimulated the proliferation of bovine lymphoblast cells at least 12-fold over background levels at maximum concentration levels. Competitive RT-PCR analysis showed constitutive levels of IL-15 mRNA within a broad range of tissues and cell types. Lipopolysaccharide addition to adherent lymph node populations caused moderate increases in IL-15 transcription while the addition of phorbol 12-myristate 13-acetate and calcium ionophore failed to induce gene expression for this cytokine. Transcription of IL-15 was also down-regulated in the presence of low concentrations of human recombinant IL-2.