HEAT-SHOCK (STRESS) PROTEINS AND GAMMA-DELTA T-LYMPHOCYTES IN ORAL LICHEN-PLANUS

Objective, Heat shock proteins (Hsps), a highly conserved class of pro tective cellular proteins that are produced under various conditions o f environmental challenge, have been implicated as the antigenic stimu lus in autoimmune diseases. Because lichen planus (LP) appears to be a n autoimmune or hyperimmune condition (mediated by T cells), Hsps may have a role in the pathogenesis of this disease. We believe that if ke ratinocyte Hsps are antigenic targets of a cellular immune response, u pregulation of these proteins should be demonstrable in tissue section s. Study design. Immunohistochemistry was used to evaluate expression of several families of Hsps in oral lichen planus tissues. The number and distribution of gamma delta T cells, a subset of T lymphocytes wit h an immune surveillance function that may contribute to autoimmunity, were also evaluated. Monoclonal antibodies to Hsps 27, 60, 70, 30, ga mma delta receptor, and CD3 (pan-T lymphocyte marker) were incubated w ith frozen sections of LP (n = 22) and normal oral mucosa (n = 17) fol lowed by an avidin-biotin-peroxidase labeling method. antibodies to ba cterial Hsps (GroEL and DnaK) were used as negative controls, and anti body to constitutive eukaryotic Hsp (Hsc70) was used as a positive con trol.Results. In six cases of LP, basal keratinocytes stained intensel y for Hsp27, whereas controls showed only slight staining. Otherwise L P and normal tissues showed comparable positive staining of upper leve l keratinocytes with anti-Hsp27. Subjective increases in antibody stai ning were noted for Hsp60 in LP, which was due in part to staining of infiltrating lymphocytes and in part to keratinocyte expression. Norma l tissues showed weak basal cell antibody staining for Hsp60. Hsp70 st aining was observed at a less intense level in LP than in controls. Ex cept for more intense basement membrane staining with anti-Hsp90 antib ody in gingiva and palate, no differences in the occurrence of this pr otein were found. Absolute numbers of gamma delta T cells were increas ed in LP when compared with those in control specimens (n = 10 vs n = 1, respectively, per high-power field). However, gamma delta T cells r epresented less than 1% of the CD3+ lymphocytes. Conclusions. It was c oncluded that normal oral mucosa expresses Hsps 27, 60, 70, and 90 and contains few gamma delta T cells. Although the expression of Hsps was altered in LP, the differences demonstrated were slight and were ther efore inconclusive. The Hsps expressed in LP could have contributed to the persistence or chronicity of the disease. or they could have simp ly reflected cellular injury.