Modulation of murine lymphocyte responsiveness by the saliva of Rhodnius prolixus (Hemiptera : Reduviidae)

Incorporation of H-3-thymidine by splenic lymphocytes was studied in CBA mi ce that were bitten by the triatomine bug Rhodnius prolixus (Stal) 14, 7, 4 , and 2 d before lymphocyte isolation, respectively. In bitten mice, both s pontaneous and mitogen-induced proliferative responses were reduced. The mo st pronounced effect was observed 4 d after exposure when lymphocytes were significantly suppressed in proliferative response to the mitogens concanav alin A, phytohemagglutinin, and bacterial lipopolysaccharide. The maximum i nhibition caused an 85% reduction of proliferation and was observed in phyt ohemagglutinin-stimulated cell cultures. The immunosuppressive effect was c aused neither by stress nor by an nonspecific cytotoxic effect of R. prolix us saliva. The described immunosuppressive activity of saliva could aid in successful repeated feedings of R, prolixus on the same host and possibly c ould play a role in transmission of Trypanosoma cruzi.