An immunofluorescence study on the cross-reaction between strep. 2a and human oral mucosa

Levels of salivary IgA in patients with minor recurrent aphthous stomatitis: a matched case-control study

OBJECTIVES

Recurrent aphthous stomatitis (RAS) is the most common oral mucosal disease. Despite plenty of studies on aetiopathogenesis of RAS, a definite cause is not clear. The objective of this study was to determine the potential changes of salivary IgA and salivary flow rate in patients affected with minor form of RAS.

MATERIALS AND METHODS

Levels of salivary IgA in 33 patients with acute RAS (minor form) and 33 matched healthy controls were determined using enzyme-linked immunosorbent assay. Resting salivary flow rates were determined too. Both measurements, levels of salivary IgA and resting salivary flow rate, were performed again for each RAS patient in remission phase.

RESULTS

Levels of salivary IgA were significantly increased in acute phase of RAS [median (interquartile range)-124.94 μg/mL (106.22-136.31)] in comparison with the levels in healthy controls [88.92 μg/mL (76.85-93.91; P < 0.001)] and with the levels in remission phase [102.4 μg/mL (84.6-120.16; P = 0.01)]. Even in the disease-free period (remission phase), levels of salivary IgA remained significantly higher in comparison with the levels in healthy controls (P = 0.01). Salivary flow rates, on the other side, were not influenced by the disease state (RAS vs. healthy), phase (acute vs. remission) or even gender (males vs. females).

CONCLUSION

Marked increase of salivary IgA in acute and remission phases of the minor RAS may suggest a potential role for this immunoglobulin in pathogenesis of the disease.

CLINICAL RELEVANCE

Salivary IgA may be an important aetiological agent in the pathogenesis of RAS, and hence, its immunomodulation may help prevent the disease.

Defining a T-cell epitope within HSP 65 in recurrent aphthous stomatitis

The 65 kD heat shock protein (HSP) has been implicated in the aetiology of recurrent aphthous stomatitis (RAS). We have previously demonstrated that peptide 91-105 derived from the sequence of mycobacterial 65 kD HSP stimulates specifically lymphocytes from patients with RAS. In this investigation, we show that both CD4+ and CD8+ T cells were significantly stimulated with mycobacterial peptide 91-105. In contrast, the human homologous peptide 116-130 stimulated only CD4+ T cells. Inhibition studies showed that CD4+ T cells were class II restricted, whereas CD8+ T cells were class I restricted. We then used truncated or substituted peptides, and demonstrated that residues 95-105 appear to be important, and residue 104(Arg) critical, in stimulating the T cells. Thus, peptide 95- 105 may constitute a T-cell proliferative epitope in RAS. We postulate that the high load of micro-organisms that colonize the oral mucosa may initiate an immune response by the microbial HSP 65-derived peptide 95-105, stimulating the numerous Langerhans cells in the oral mucosa to activate a cross-reacting immune response to the homologous peptide 116-130 within the epithelial HSP 60, initiating the immunopathological changes that lead to RAS.

Recognition of a unique peptide epitope of the mycobacterial and human heat shock protein 65-60 antigen by T cells of patients with recurrent oral ulcers

T cell epitopes of the 65-kD heat shock protein (hsp) were investigated in patients with recurrent oral ulcers (ROU). Peripheral blood mononuclear cells were stimulated with overlapping synthetic peptide (15ers), derived from the sequence of the 65-kD hsp of Mycobacterium tuberculosis. Specific lymphoproliferative responses were stimulated only with peptide 91-105 in ROU, compared with healthy or disease controls (P < 0.01). This was confirmed by studying 760 short term cell lines generated with the 65-kD hsp and then stimulated with the peptides. The frequency of short term cells lines responding to peptide 91-105 in ROU was significantly greater than in healthy (P < 0.0001) or disease controls (P < 0.01). A comparative investigation with the homologous human 60-kD hsp peptide 116-130 also showed significantly greater lymphoproliferative responses in ROU than in healthy (P < 0.01) or disease controls (P < 0.001). The potential involvement of the T cell epitope 91-105 in the pathogenesis of ROU is supported by finding a significant increase in the lymphoproliferative responses stimulated with peptide 91-105 during the stage of ulceration, compared with remission in 9/11 patients studied sequentially (P < 0.05). The results suggest that oral ulceration might be initiated by the microbial hsp peptide 91-105 stimulating the mucosal Langerhans cells, which may generate autoreactive T cell clones primed to the homologous peptide 116-130.