Spontaneous cytokine gene expression in normal guinea pig blood and tissues

The authors report, for the first time, the cloning, characterization and sequencing of guinea pig cDNAs for interleukin (IL)-2, IL-10, IL-12p40, and transforming growth factor beta (TGF-beta). Partial cDNAs for two additional cytokines, IL-1alpha and TNF-alpha, whose sequences are present in the GenEMBL database, were also cloned. The IL-10 clone is a full-length cDNA, while the remaining clones are partial cDNAs. The guinea pig cDNA sequences have high identity with their mouse and human counterparts. Northern blot analysis revealed that the guinea pig transcripts range in size from 1.0 kb to 2.2 kb. The constitutive expression of cytokines in two strains of guinea pig (C4D, Albany) that differ in susceptibility to infection with Treponema pallidum was examined. Since susceptibility to T. pallidum is also age dependent, both neonates and adults were examined. Spontaneous cytokine expression was examined in peripheral blood, skin, spleen, lymph node, brain, and peritoneal cells. In skin, lymph node, and peripheral blood, very low levels of IL-1alpha, IL-12p40, tumour necrosis factor alpha (TNF-alpha), and TGF-beta and moderate levels of IL-2 and IL-10 were observed. Cytokine gene expression was not observed in spleen and brain. Peritoneal cells expressed only TGF-beta. Age- and strain-associated differences were not observed, except for IL-12p40, which was elevated in guinea pigs resistant to T. pallidum infection (C4D neonates, Albany adults).