Human anti-rhinosporidial antibody does not cause metabolic inactivation or morphological damage in endospores of Rhinosporidium seeberi, in vitro.

This report describes the use of the MTT-reduction and Evan's blue-staining tests for the assessment of the viability and morphological integrity, respectively, of rhinosporidial endospores after exposure to sera from rhinosporidial patients with high titres of anti-rhinosporidial antibody. Sera from three patients, with nasal, ocular and disseminated rhinosporidiosis respectively were used, with human serum without anti-rhinosporidial antibody for comparison, with or without added fresh guinea pig serum as a source of complement. All four sera tested, with or without guinea-pig serum, had no effect on the morphological integrity or the viability of the endospores and it is suggested that anti-rhinosporidial antibody has no direct protective role against the endospores, the infective stage, in rhinosporidiosis. This finding is compatible with the occurrence of chronicity, recurrence and dissemination that are characteristic of rhinosporidiosis despite the presence of high titres of anti-rhinosporidial antibody in patients with these clinical characteristics. The possible occurrence of humoral mechanisms of immunity that involve anti-rhinosporidial antibody with cells such as leucocytes and NK cells, in vivo, cannot yet be discounted, although the presence of high titres of anti-rhinosporidial antibody in patients with chronic, recurrent and disseminated lesions might indicate that such antibody is non-protective in vivo.

The relationship between reactivities to lepromin A (Fernandez and Mitsuda) and a soluble protein antigen of Mycobacterium leprae.

Three methods of evaluation were used to investigate the relationship between skin test reactions elicited by different antigens of Mycobacterium leprae. The latter were the Fernandez and Mitsuda reactions to lepromin, and that to a Soluble Protein Antigen (SPA) of M. leprae. All three methods of evaluation demonstrated some degree of relationship though not as high as would be expected. The closest correlation was between Mitsuda and SPA reactions; while Fernandez and Mitsuda, and Fernandez and SPA reactions showed more or less similar coefficients of correlation.