19S and 7S Anti-Toxoplasma Antibodies in Diagnosis of Acute Congenital and Acquired Toxoplasmosis. ∗

Summary

An attempt was made to determine if macroglobulin (19S) anti-Toxoplasma antibodies are produced during the acute stage of infection and, if so, if their demonstration is of diagnostic significance. Sera were obtained from established cases of acute congenital and acquired toxoplasmosis and separated by gradient ultracentrifugation or gel filtration. Serologic examination of the fractions obtained by these methods revealed that 19S anti-Toxoplasma antibodies are formed in both acute congenital and acquired infection with Toxoplasma. Only 7S antibodies were demonstrated in infants born of mothers with chronic toxoplasmosis and in adults with longstanding infection with this organism. The demonstration of such macroglobulin antibodies in suspect cases of acute toxoplasmosis appears to be a useful adjunct to the presently available serologic tests.

ADDENDUM. Since submitting this manuscript, sera have been obtained from 5 additional cases of acute congenital toxoplasmosis; 19S as well as 7S antibodies were demonstrated in each case. Two of the mothers had only 7S antibodies and in three, they were of both the 19S and 7S class. 19S antibodies were demonstrated in acute phase sera in each of ten additional cases of acquired infection.