CD 57 expression on lymphocytes present in the caecum and caecal tonsils in broilers infected with Eimeria tenella

In order to detect and establish the expression of the CD57 lymphocyte population in the caecum and caecal tonsils in broilers, immunohistochemical studies of tissue samples of broilers experimentally infected with E. tenella at 21 days of age were carried out. Immunohistochemical investigations were performed with the aid of the avidin-biotin technique (LSAB), by using mouse monoclonal anti- CD57 antibodies. Increased immunoreactivity of the lamina epithelialis, mucosal lamina propria and caecal submucosa was detected as early as two days after infection, increasing at its highest at the end of the fourth day after infection. On the fifth, sixth and seventh day after infection the degree of expression of CD57 lymphocytes in the caecal mucosa of experimental birds decreases. The immunoreactivity of the tissue of the stroma of the mucosal and submucosal lamina propria of the caecal tonsils was most intensive the fourth, sixth and seventh day after infection. A discrete immunoreactivity decrease was present during the fifth day after infection. The so established CD57 lymphocyte population activity in the caecum and caecal tonsils substantiates the existence of NK cytotoxic activity of intraepithelial lymphocytes, as well as the role of these cells in the intestinal mucosa defense mechanisms against intracellular microorganisms