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

Immunologic cross-reactions between Strep. 2A, fetal human oral mucosa (FHOM), and adult human oral mucosa (AHOM) were investigated by the use of a double layer immunofluorescence staining technique. Rabbit sera were prepared against Strep. 2A and FHOM. Seventeen sera from patients with recurrent aphthous stomatitis (RAS) and with known antibodies against Strep. 2A and AHOM were examined for antibodies against FHOM. The distribution of endpoint titers against FHOM in the sera from RAS differed significantly from the distribution in 17 controls. The immune absorptions in the rabbit sera and in the 17 sera from patients with RAS indicate that some cross-reacting antigenic determinants are shared between Strep. 2A, FHOM, and AHOM. Further, the present results indicate that antibodies are produced against antigenic determinants which are not shared by Strep. 2A, FHOM, and AHOM. The role of cross-reacting antigens in the pathogenesis of RAS is discussed but remains obscure.