Determination of IgA antibodies colostrum against Mycobacterium antigens.

Colostrum, the first milk secretion, is characterized by a high concentration of immunologically active molecules with neutralizing and antibacterial capabilities. Mycobacterium tuberculosis is a microorganism primarily infecting the lungs but can also affect non-pulmonary tissues. Despite a BCG vaccination coverage exceeding 97% in Mexico, pulmonary and meningeal tuberculosis cases have shown a yearly increase. This study aimed to determine the presence of IgA antibodies against soluble extracts from H37Rv M. tuberculosis and BCG antigens in colostrum samples from Mexican mothers. Quantification of IgA subclasses and colostrum reactivity to Mycobacterium were performed via ELISA using 106 colostrum samples from healthy Mexican mothers. Results indicated that 87.7% of the analyzed colostrum samples contained total IgA antibodies, with 77% exhibiting IgA2 antibodies against H37Rv, of which 22.6% and 17.9% showed high titers, respectively. Among the H37Rv antigen-positive samples, 80% recognized the BCG antigen. In conclusion, most of the analyzed colostrum samples from women contained IgA antibodies against M. tuberculosis antigens and demonstrated BCG reactivity. Most of these antibodies belonged to the IgA2 subclass, suggesting a potential protective effect against tuberculous meningitis in nursing infants.