In vivo study on dual-signal hypothesis and its correlation to immune response using mycobacterial antigen.
Aravindhan Vivekanandhan; Sulochana Das
Current Science, 2001; 81: 301-304.
Antigens have the innate ability to trigger both mitosis and apoptosis simultaneously (dual-signal hypothesis). The fate of the cell depends on the dosage and duration of the trigger. In the present study, dual-signal hypothesis was tested in a murine model using a mycobacterial antigen (purified protein derivative-PPD). As a positive control, E.coli -lipopolysaccharide (LPS) was used. The results were correlated with the humoral immune response. Our results showed that PPD had induced apoptosis in thymus only (after 7 days), while LPS had induced apoptosis in both thymus and bone marrow (after 18 h). Further, the plasma from PPD-treated animals had higher levels of Mycobacterium tuberculosis -specific antibodies and also recognized a few M. tuberculosis -specific antigens on immunoblot. To conclude, PPD has induced thymic apoptosis and has also elicited a potent antibody response.
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