Immunological studies in children with acute viral hepatitis.

Sera from 116 consecutive unselected cases of sporadic acute viral hepatitis in children were examined for hepatitis B antigen (HBAg), smooth-muscle autoantibodies (SMA), other autoantibodies and immunoglobulins, and skin tests were performed with dinitrochlorobenzene (DNCB). HBAg was detected in twenty-one and SMA in ninety-eight out of 116 sera that had been obtained during the 1st or 2nd week from the onset of jaundice. Hepatitis B antigen was present in seventeen out of the eighteen SMA negative patients (94-4%) and in only four out of the ninety-eight SMA-positive patients (4-1%). The presence of SMA was not related to the sex and age of the patients or to the serum bilirubin and transaminase levels. SMA did not persist for more than 6 weeks from the onset of jaundice in most of the cases. In twenty-eight out of forty-one sera which were tested the IgM level was found to be elevated during the acute phase of illness and within normal limits during the recovery stage. A negative correlation between the presence of SMA and the elevated serum IgM level and the presence of HB Ag in the same patients was observed. The DNCB skin test was found to be positive in all fifty-two patients who did not have HBAg in their serum and in twenty out of the twenty-one patients who had circulating HbAg. From these findings there appears to be no gross impairment of cell-mediated immunity in acute viral hepatitis, and hepatitis A is associated with SMA production and an increase in serum IgM levels, when compared to hepatitis associated with HBAg.