RESUMEN
When tested for possible blocking effect on the cercarial, serine proteinase, elastase [CE] activity, an iridoid mixture extracted from leaves of Citharexylum quadrangular abolished 31% of the enzyme activity at final concentration l5 micro g. When formulated in jojoba oil and applied to mice tails followed by infection with Schistosoma mansoni cercariae, the iridoid mixture blocked cercarial penetration and caused significant reducetion [94%; P < 0.05] in worm burden in treated mice in comparison to controls. Also, immunomodulatory effects of iridoid mixture, iridoid-treated S. mansoni worm homogenate on mice were studied by measuring IgG and IgM levels against E. coil lysates [ECL], solube S. mansoni worm antigenic preparation [SWAP] and cancer bladder homogenates [CBH] as antigens by ELISA. Cellular immune responses were studied by calculating mean percent of CD4+, CD8 +/- T, B-mesenteric lymph node cells [MLNC] and CD4+, CD8 +/- T thymocytes by direct immuno-fluorescence staining in treated mice as compared to untreated homogenate given mice or untreated mice. Injecting mice with serial dilutions of iridoid mixture resulted in fluctuation, peaks and troughs, in both IgG and IgM responses against the above mentioned antigens. lst and 2nd immunizations with iridoid mixture treated homogenate resulted in significantly elevated [P < 0.05]. 1gM and IgG levels against the 3 used antigens in comparison with sera from control mice. Immunized mice with homogenate treated with iridoid mixture showed a significant increase [P < 0.05] in CD4+T thymocytes, a non significant increase in CD8+T thymocytes, a significant increase [P<0.05] in CD4+T lymphocytes [MLNC] and a non significant increase in CD8+T- and B-lymphocytes [MLNC] compared with mice immunized with untreated homogenate or non-injected normal mice