Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 1997
Publication Date: N/A
The bovine interleukin-15 (IL-15) sequence was cloned from abomasal lymph node mRNA by enzymatic amplification of cDNA using human primers. The open reading frame is 486 base pairs in length and the proposed protein sequence shows 78.4%, 73.5% and 84.6% similarity with that predicted for the human, mouse and swine sequences, respectively. Expressed and purified recombinant bovine IL-15 in the absence of the 48-amino acid leader sequence sucessfully stimulated the proliferation of bovine lymphoblast cells at all concentration levels tested. Competitive RT-PCR analysis using a truncated IL-15 gene sequence as an internal standard showed constitutive levels of IL-15 mRNA within a broad range of tissues and cell types. Lipopolysacharide 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 gen expression for this cytokine. Transcription of IL-15 was down-regulated in vitro in the presence of low concentrations of human recombinant interleukin-2. When IL-15 transcription was analyzed in mucosal and regional lymph node populations from bovine infected with Ostertagia ostertagi or Cryptosporidium parvum, no discernable changes in mRNA levels were detected in O. ostertagi infected animals; however, an apparent reduction in IL-15 transcription was observed in intraepithelial lymphocytes from animals 7 days after a C. parvum infection. This reduction corresponded with an increase in the numbers of CD4+ and CD8+ cell populations.