Cell-mediated immune responses (CMIR) in human rhinosporidiosis

Cell mediated immune responses (CMIR) to Rhinosporidium seeberi in human pa tients with rhinosporidiosis have been studied. With immuno-histochemistry, the cell infiltration patterns in rhinosporidial tissues from 7 patients w ere similar. The mixed cell infiltrate consisted of many plasma cells, fewe r CD68+ macrophages, a population of CD3+ T lymphocytes, and CD56/57+ NK ly mphocytes which were positive for CD3 as well. CD4+ T helper cells were sca rce. CD8+ suppressor/cytotoxic-cytolytic cells were numerous. Most of the C D8+ cells were TIA-l+ and therefore of the cytotoxic subtype. CD8+ T cells were not sub-typed according to their cytokine profile; 1L2, IFN-gamma (Tcl ); IL4, ILS (Tc2). In lympho-proliferative response (LPR) assays in vitro, lymphocytes from rhinosporidial patients showed stimulatory responses to Co n A but lymphocytes from some patients showed significantly diminished resp onses to rhinosporidial extracts as compared with unstimulated cells or cel ls stimulated by Con A, indicating suppressor immune responses in rhinospor idiosis. The overall stimulatory responses with Con A suggested that the rh inosporidial lymphocytes were not non-specifically anergic although compari sons of depressed LPR of rhinosporidial lymphocytes from individual patient s, to rhinosporidial antigen with those to Con A, did not reveal a clear in dication as to whether the depression was antigen specific or non-specific. The intensity of depression of the LPR in rhinosporidial patients bore no relation to the site, duration, or the number of lesions or whether the dis ease was localized or disseminated. Rhinosporidial extracts showed stimulat ory activity on normal control lymphocytes, perhaps indicating mitogenic ac tivity. These results indicate that CMIR develops in human rhinosporidiosis , while suppressed responses are also induced.