ABSTRACT
Immunization of mice with Saccharomyces boulardii crude extract caused a significant reduction in Schistosoma mansoni worm burden [23.7%; P = 0.02] in comparison to control mice. Mice sera collected after the 1st immunization showed a significant increase [P < 0.05] in both IgM and IgG against parasite soluble cercarial antigenic preparation [CAP] than unimmunized mice sera [UMS]. Upon 2nd immunization, sera from yeast extract immunized mice [YIM] showed increase of IgM and IgG [1.6 and 1 fold] against CAP than UMS. Sera collected 2, 4 and 6 weeks [W] after infection of YIM with S. mansoni cercariae showed higher 1gM [1.4, 1.5 and 1 folds] and IgG [0.9, 1.2 and 1.1 folds] levels against CAP than sera of infected UM [IUM]. When compared to sera from UM, a week post lst and 2nd immunization sera showed a significant elevation [P < 0.05] of both IgM and IgG to parasite soluble adult worm antigenic preparation [SWAP]. Sera collected at 2, 4 and 6W after infection of YIM with parasite cercariae showed higher 1gM [11, 1.3 and 1.2 folds] and IgG [1.2, 1.1 and1.3 folds] reactivities against SWAP than sera of IUM. One week post 1t and 2 immunization with the yeast extract, sera showed a significant increase [P < 0.05] of both 1gM and IgG levels against parasite soluble egg antigen when compared with sera from UM. At 2 and 4W post infection, sera from immunized infected mice showed a significant decrease in IgM [P < 0.05] but the decrease of IgG [0.7 fold] was not significant when compared to IUM. Six weeks post infection the decrease in both antibodies remained but it was significant for IgG [P < 0.05] but not for IgM [2.1 folds] when compared with IUM. Immunization with S. boulardii extract caused a non-significant increase [1.2 folds] in mesenteric lymph node [MLN]-CD4+T cells, significant elevation of MLN-CD8+T cells [P < 0.05] and a non-significant increase [0.9 folds] of B-cells when compared to that of UM. Also, Immunization with S. boulardii extract caused 1 fold elevation in both CD4+ and CD8 +/- T lymphocytes in thymus of YIM when compared with their counts in thymus of UM