Trypanosoma evansi: Immune response and acetylcholinesterase activity in lymphocytes from infected rats

[Display omitted] ► Trypanosoma evansi is transmitted to the host. ► Multiply in the skin or mucosa. ► Increase the population and the antigenic diversity of parasites. ► Stimulating the production of B cells and T cells. ► Lymphocytosis. ► Cholinergic receptors in the immune system cells. ► Acetylcholine is involved in the regulation of immune function. ► Acetylcholinesterase. ► Hydrolyses esters with acetyl group (as acetylcholine). ► Change in cholinesterase activity in rats infected with T. evansi. ► Alteration related to immune response. ► Inflammation. The existence of cholinergic receptors in the immune system cells is well documented. This study aimed to evaluate the acetylcholinesterase activity (AChE) in lymphocytes from rats infected with Trypanosoma evansi in acute and chronic phase disease. Twenty animals were infected with 106 trypomastigotes forms each and 10 were used as negative controls. The two groups of inoculated rats were formed according to the degree of parasitemia and the period post-infection (PI). Group A: rats with 4days PI and between 24 and 45parasites/field (1000×); group B: rats with 30days PI and parasitemia with jagged peaks between 0 and 1parasites/field; group C: not-infected animals. At 4days PI (acute phase) and 30days PI (chronic phase) the rats were anesthetized to collect blood for hemogram and separation of lymphocytes. After separation, the AChE activity was measured in lymphocytes. It was observed that the number of lymphocytes increased significantly in group A compared to group C. The activity of AChE in lymphocytes significantly increased in acute phase and decreased in chronic phase in the infected rats when compared to not-infected (P