Antigen-specific B-cell unresponsiveness induced by chronic Mycobacterium avium subsp. paratuberculosis infection of cattle
Mycobacterium avium subsp. paratuberculosis infection of cattle results in a chronic granulomatous enteritis. Clinical disease (i.e., cachexia, diarrhea, and high fecal bacterial counts) is preceded by a lengthy subclinical stage of disease. The immunologic mechanisms associated with the progression of infected cattle from subclinical to clinical disease are unclear. In this study, a cell proliferation assay was used in combination with flow cytometry to compare peripheral blood lymphocyte responses of cattle with subclinical paratuberculosis to responses of cattle with clinical paratuberculosis. B cells from cattle with subclinical disease proliferated vigorously upon stimulation with M. avium subsp. paratuberculosis antigen, with up to 12.4% of the total B cells responding. However, B cells from cattle with clinical disease did not proliferate upon antigen stimulation despite good proliferation in response to concanavalin A stimulation. In addition, these animals had high percentages of peripheral blood B cells. B cells from noninfected animals did not proliferate upon M. avium subsp. paratuberculosis antigen stimulation. Thus, it appears that B-cell proliferation is a sensitive indicator of subclinical Johne's disease. Furthermore, the immunologic mechanisms responsible for the antigen-specific unresponsiveness of peripheral blood B cells may be significant in the eventual progression from subclinical to clinical Johne's disease in cattle.
THIS PAPER EXPLAINS WHY SOME CD PATIENTS IN THE ACTIVE STAGES OF THE DISEASE DO NOT MOUNT AN IMMUNE RESPONSE AGAINST MAP AND DO NOT DEMONSTRATE SERUM ANTIBODIES AGAINST MAP. OPPONENTS OF THE MAP THEORY USE THE LACK OF AN IMMUNE RESPONSE AND SERUM ANTIBODIES TO ARGUE AGAINST THE MAP THEORY OF THE ORIGINS OF CD. HOWEVER, THIS PAPER COUNTERS OPPONENTS' ARGUMENTS QUITE EXQUISITELY.
Source: http://www.crohns.org/articles/1999_04_1593-8_ii.htm Contact PARA: http://www.crohns.org/contact.htm
Paratuberculosis Awareness & Research Association