Regulation of bovine IL-12Rβ2 subunit mRNA expression in bovine lymph node cells

Abstract

The β2 subunit of the interleukin (IL)-12 receptor (IL-12Rβ2) has been shown to play an essential role in differentiation of T helper 1 (Th1) cells in the murine and human system, and antibodies raised against IL-12Rβ2 recognized this molecule on human Th1 but not Th2 cells. However, while the cytokines secreted by clones of murine cells allowed the definition of distinct T helper cell subsets, bovine clones with polarized Th1 and Th2 cytokine profiles were rarely found. This raised important questions about the regulation of immune responses in cattle. We therefore cloned bovine IL-12Rβ2 (boIL-12Rβ2) DNA complementary to RNA (cDNA) from the start codon to the 3′ end of the mRNA. Comparison of boIL-12Rβ2 cDNA with human and murine IL-12Rβ2 cDNA sequences revealed homologies of 85 and 78%, respectively. The deduced protein sequence showed the hallmark motifs of the cytokine receptor superfamily including the four conserved cysteine residues, the WSXWS motif and fibronectin domains in the extracellular part as well as a STAT4 binding site in the intracellular part of the molecule. Using real-time reverse transcription–polymerase chain reaction, upregulation of mRNA expression of this molecule could be demonstrated in cultured bovine lymph node cells stimulated with phytohemagglutinin. Furthermore, cells with upregulated boIL-12Rβ2 mRNA responded with enhanced expression of interferon γ to treatment with interleukin 12.