Serological study of an allergic agranulocytosis due to noramidopyrine.

An allergic agranulocytosis induced by amidopyrine and triggered by noramidopyrine was studied. Leucoagglutinating and leucocytotoxic antibody, active only in the presence of the drug, was demonstrated. The antibody was stable, giving a titre from 1·34 to 1·62 and was present in the IgM (19S globulin) and in the IgG (7S globulin) serum fractions. The site of drug fixation was studied by use of iodoantipyrine labelled with 131I; a stable fixation was demonstrated on to the IgM and IgG globulins. Special emphasis is given to cross-reaction with compounds related to amidopyrine.