In another article from www. immuno-scilab. com the systemic and mucosal humoral immune response is of great importance in the elimination and prevention of G. lamblia infections. In mice, the appearance of IgA in intestinal secretions has been shown to have a correlation with the infection’s resolution. The finding of a significant association between secretory IgA in human milk and prevention of diarrhea due to Giardia adds to the evidence of a protective role of specific SigA against giardiasis and further strengthens the importance of breast-feeding infants to prevent diarrheal disease
In addition to the diagnostic and protective role of secretory IgA, Mac and McLeod (J. Clin. Invest. 90: 2585, 1992) clearly demonstrated that whey secretory immunoglobulin-A to human Toxoplasma gondii was capable of reducing the infection of the enterocytes by the parasite. Whey from 17women (four acutely infected with Toxoplasma gondii, eight chronically infected, and five uninfected) was studied. T. gondii-specific secretory IgA antibodies were demonstrated by ELISA in whey from acutely infected and one of eight chronically infected women.
All other samples from non-infected women were negative. Incubation of T. gondii tachyzoites with whey or purified secretory IgA from acutely infected (but not seronegative) women caused a 50-75%reduction in infection of enterocytes in vitro. Whey reactive with the 46-kD epitope from three of six chronically infected women caused less (> 4o%) inhibition. Whey and purified secretory IgA from two of three acutely infected women agglutinated tachyzoites.
These results indicate that it may be possible to produce human secretory IgA to T. gondii capable of reducing initial infection of enterocytes, as such IgA is present during natural infection. Moreover, this study also demonstrated that T. gondii-infected humans produce secretory IgA specific to T. gondii, which has a diagnostic implication. Overall, the secretory immune response demonstrated in saliva has been used to reflect the result of antigenic exposure in the gut, which includes intestinal parasites.
Furthermore, studies have established that secretory IgA production at one location can be stimulated in response to infection at another mucosal site. Indeed, salivary IgA was found to be the most accurate predictor of a duodenal IgA response during the first four weeks after onset of rotavirus infection.
Works cited : Roitt, I. , Brostoff, J. , & Male, D. (1993). Immunology: Third Edition. London, England: Mosby-Year Book Europe Limited. Guyton, A. C. , & Hall, J. E. (2000). Textbook of Medical Physiology: Tenth Edition. Philadelphia, USA: W. B. Saunders Company.