Possible role of superantigens in inducing autoimmunity in pemphigus patients

The diagnostic and pathological relevance of anti-desmoglein autoantibodies in common forms of pemphigus has been well established, and T cells have been shown to play a role in the onset and progression of these diseases. The role of superantigens in provoking polyclonal activation of T cells with many different fine specificities, possibly including autoreactive T cells and T-cell mediated autoantibody response, is unknown. Further, abnormal T-cell function may lead to opportunistic infections particularly with Candida. The response of T cells of pemphigus patients to recall antigens of these opportunists is not clear. The aim of this study was to investigate the in vitro response of T lymphocytes from pemphigus patients to common bacterial superantigens such as streptococcal pyrogenic exotoxin A and staphylococcal enterotoxin B, and recall antigens such as Candida antigen. Changes in CD3(+) CD4(+) and CD3(+) CD8(+) T-cell sub-populations and expression of naive/memory markers (CD45RA(+) /RO(+)) on different T cells were analyzed by flow cytometry. Significant elevation in CD3(+) CD4(+) and expression of the memory (CD45RO(+)) markers on these cells was observed both in pemphigus vulgaris and pemphigus foliaceus patients, as compared to healthy controls, upon stimulation with streptococcal pyrogenic exotoxin A and staphylococcal enterotoxin B. However, only memory T cells (CD45RO(+)) were significantly increased upon Candida antigen stimulation. Our study suggests that CD4(+) memory T lymphocytes may modulate the pathogenic autoantibody response in pemphigus patients, and also emphasizes the possibility that the superantigen-reactive T cells participate in the triggering of autoimmunity in pemphigus.