Pulmonary Alveolar Macrophages Reveal Higher Basal Cytokine mRNA Expression than Peripheral Blood Leucocytes in Healthy Piglets

The host immune system plays a vital role in protection from various harmful stimuli. Cytokines play a very important role in infammation and immune response even at minimal concentrations. In this study, basal mRNA expression of various cytokines in porcine pulmonary alveolar macrophages (PAM) and peripheral blood leukocytes (PBL) of healthy piglets was assessed. Basal expression of all cytokines was higher in PAM as compared to PBL and the differences in normalized threshold cycle values ranged between 13.6% (IFN-α) and 53% (IFN-β). There was a positive correlation between the expression patterns in PAM and PBL, with a correlation coeffcient of 0.76. Relative quantifcation of cytokine mRNA in PAM showed that there was wide variation in the degree of expression in terms of fold changes, which ranged from 3.5 (IFN-α) to 1130.6 (IFN-β). The results showed that exposure levels to pathogens can infuence the basal cytokine expression, which depends on the microenvironment even in healthy piglets.