Immune response and immunodepression in Hymenolepis diminuta infection in rats.

Maximum size range of Hymenolepis diminuta was found in rats 22 days postinfection (p.i.) with single or several (3-6) tapeworms. Immunologic reactions of the host were connected with the growth and development of parasites. Positive results of macrophage migration inhibition test (MMI) were recorded from 7 until 22 days p.i. in infection with a single and to 16 days p.i. in those with 3-6 H. diminuta. The negative results of the MMI test observed at later postinfection times are considered as a manifestatioin of immunosuppression caused by the presence of H. diminuta. The expulsion of tapeworm by anthelmintic treatment with Yomesan restored for a short time cell-mediated immunity, as demonstrated by MMI test. The level of antibodies, as determined by passive hemagglutination test (HA), varied during the infection; it was highest at 22 days p.i. The removal of tapeworms as a result of drug treatment caused a rise in titers.