Immunomodulatory effect of dietary selenium supplementation on serum antibody response and leucocytic profile of <i>Trypanosoma brucei brucei</i> infected rats

Abstract

Effect of selenium supplementation on the immune response of Trypanosoma brucei brucei infected rats was investigated. Twenty five (25) adult male albino rats divided into five groups of five rats each were used for this study. Groups A, B and C were fed 4, 8 and 16 part per million (ppm) selenium in their feed, respectively. Groups D and E were not given selenium supplementation. The supplementation started on day 0, followed by the infection of groups A, B, C and D with T. brucei brucei on day 14 post supplementation (PS). Immune response of the rats was assessed by determining the antibody response to sheep red blood cells (SRBC) using direct haemagglutination technique and total and differential leucocyte counts. The supplementation led to significant (p < 0.05) increase in antibody response to sheep red blood cell of the supplemented groups at pre- and post infection when compared with the control. The infection however, led to decrease in antibody titre but remained higher than the pre-supplementation titre. Also, the supplementation led to increase (p < 0.05) in leucocyte counts prior to infection on day 14 PS. The increase in total leucocyte count could be attributed to increase in lymphocyte and neutrophils. The mortality record showed that all rats (100%) in the infected, not supplemented group and 2 rats (40%) died from the 16 ppm group by day 42 PS. No rat died in 4, 8 ppm and not infected, not treated groups.

Key words: Selenium, antibody titre, leucocytes, trypanosomes, immunosuppression.