Expression of proinflammatory cytokine mRNA in the lymphatic organs of adult and neonatal pigs

Inflammatory cytokine mRNA expression in the lymphatic organs of neonatal, 1-month-old and adult pigs was compared. The mRNA expression of interleukin (IL)-1β, IL-6, IL-18 and tumor necrosis factor (TNF)-α in the spleen, thymus, tonsil and popliteal and mesenteric lymph nodes was investigated by semi-quantitative RT-PCR. Stronger IL-1β mRNA expression was observed in the 1-day-old and 1-month-old piglets than in the adult pigs. In thymus, tonsil and mesenteric lymph node, IL-1β mRNA expression in 1-day-old piglets was stronger than in 1-month-old pigs. The expression of IL-6 mRNA in the 1-day-old and 1-month-old tonsil tended to be stronger than in the adult pigs. IL-18 and TNF-α mRNA expression was constant in all the samples examined. The expression of IL-1β and IL-6 mRNA may reflect an inflammatory reaction against the exo- and endogenous foreign bodies occurring in the lymphatic organs, especially in the tonsil, of neonatal piglets.