Natural antibodies to procaine amide.

A method has been developed for assay of antibody reactive with procaine amide (PrA) which utilizes sheep red blood cells coupled with diazotized PrA. Antibody of the IgM class was found in 19–50% of the populations tested. These included patients with systemic lupus erythematosus (SLE), rheumatoid arthritis, juvenile rheumatoid arthritis, miscellaneous diseases, cardiac patients receiving PrA and normal adults. Only 6% of patients with PrA-induced systemic lupus erythematosus had antibody. Antibody was not found in neonatal children, nor in rabbits and hamsters, but was found in 78% of normal dogs. Immunization of rabbits with a PrA–bovine serum albumin complex induced anti-PrA antibody in high titre. Antibody titres in these rabbits and in man could be abolished by addition of PrA to the titration system. Seventy-four per cent of unselected patients receiving PrA for over 2 months were found to have antinuclear antibody in significant titre. It is suggested that the high incidence of antinuclear antibody and SLE-like disease in patients receiving PrA may be related to the wide occurrence of natural antibody to PrA.