Differential production of immune parameters by mouse strains that differ in their susceptibility to <i>Trypanosoma brucei brucei</i>

Abstract

African trypanosomes are extracellular protozoan haemoparasites causing sleeping sickness to man or nagana to livestock in sub-Saharan Africa. Efforts to control trypanosomiasis have been hampered mainly by the parasites\' ability to constantly undergo antigenic variation. Characterization of immune mechanisms responsible for resistance during trypanosomosis may unravel novel strategies to control the pathogenic consequences of the disease. In the present study, we analyse the severity of infection and immune responses during the acute phase of Trypanosoma b. brucei infection in mouse stains (Balb/c, C57B1/6, C3H/HeNand {Balb/c×C57B1/6} F1 i.e. CB6-F1), that differ in their susceptibility to infection. Mice were intraperitoneally inoculated with 2 Differential productions of immune parameters by mouse strains that differ in their susceptibility to Trypanosoma brucei brucei. Morbidity was quantified by rough coat, reduced activity/movement and anaemia. The kinetics production of plasma level tumor necrosis factor (TNF) and interleukin-4 (IL-4) were evaluated by cytokine-specific sandwich ELISA. Further more, plasma from T.b. brucei-infected mice were tested in antibody-specific ELISAs for variant-specific surface glycoprotein (VSG) reactivity to determine the levels of VSG-specific antibodies. Results showed that T.b. brucei-infected mice differentially produce TNF. Mice (C57B1/6, CB6-FI) that efficiently controlled parasitaemia exhibited significantly higher plasma TNF levels during and after the first peak of parasitaemia than those showing reduced ability to control parasitaemia (C3H/HeN, Balb/c). Furthermore, the production of IL-4 was observed in all mouse strains except for C3H/HeN which exhibited the most susceptible phenotype. Interestingly, infected C3H/HeN mice showed a greatly reduced antibody-searching ability as compared to other strains. Data from this study suggest that resistant in T.b. brucei-infected mice is associated with the production of increased levels of TNF, coupled with low but sufficient le veils of IL-4 and increased antibody levels during the acute phase of infection.

The Kenya Veterinarian Vol. 27 2004: pp. 109-112