Comparison of Antibody Responses against Two Molecules from Ascaris lumbricoides: The Allergen Asc l 5 and the Immunomodulatory Protein Al-CPI

SIMPLE SUMMARY: Helminth infections may have different effects on human health, including risk or protection from other diseases. Ascariasis (caused by Ascaris lumbricoides), the most common soil-transmitted helminthiasis, can induce allergic responses, and also immunosuppression. During ascariasis, antibodies for many A. lumbricoides antigens are produced; however, there is no clear information about the concurrent IgE, IgG4 and IgG production as well as their influences on the actual allergic reactions. In this study, we evaluated antibody responses to two A. lumbricoides molecules, rAsc l 5 and rAl-CPI (an anti-inflammatory product), in an A. lumbricoides endemic population and explored their relationship with the infection and asthma. Our results show that both molecules induce specific antibodies, but, in contrast to rAl-CPI, rAsc l 5 activates cells associated with allergic reactions in some individuals. All together, these data suggest that these molecules have differences in the elicited immune response. ABSTRACT: Immunity to Ascaris lumbricoides influences the pathogenesis of allergic diseases. Antibody responses to its proteins have been found to be associated with asthma presentation; however, helminth products that induce immunosuppression have been reported, which also raise specific antibodies. We aimed to evaluate antibody responses (IgE, IgG4 and IgG) to two A. lumbricoides molecules, Asc l 5 and Al-CPI (an anti-inflammatory Cysteine Protease Inhibitor), in an endemic population, exploring their relationships with the infection and asthma. The two molecules were produced as recombinant proteins in E. coli expression systems. Specific antibodies were detected by ELISA. Lower human IgE, but higher IgG4 and IgG antibody levels were observed for Al-CPI than for rAsc l 5. The IgE/IgG4 isotype ratio was significantly higher for Asc l 5 than for Al-CPI. In humans Al-CPI did not induce basophil activation as has been previously described for Asc l 5. In mice, Al-CPI induced fewer IgE responses, but more IgG2a antibody titers than rAsc l 5. Our results suggest that these molecules elicit different patterns of immune response to A. lumbricoides.