Detection of human autoantibodies specific for 5'-m7GMP and m7G(5')ppp(5')N

An enzyme-linked immunosorbent assay was utilized for the detection of spontaneously occurring antibodies with apparent specificities for m7G, 5'-m7GMP, and m7G(5')ppp(5')C. From the sera of 50 patients containing anti-nuclear antibodies, 48 (96%) possessed antibodies which bound to one or more immobilized nucleoside-BSA antigens (A-, G-, C-, U-, and T-BSA). Additionally, 8 (16%) of these sera contained immunoglobulins that reacted with m7G-BSA antigen. In these latter sera, soluble competitors such as m7G, 5'm7GMP, and m7G(5')ppp(5')C (but not 5'-AMP, -GMP, -CMP, -UMP, and -TMP or m1G and m22G) effectively inhibited antibody-binding to immobilized m7G-BSA. These results indicate the existence of spontaneously occurring anti-m7G antibodies in autoimmune diseases which are distinct from anti-G antibody populations.