Comparison of complement--fixation and immunodiffusion tests for the detection of hepatitis-associated antigen.

Abstract

Hepatitis-associated antigen (HAA) was detected by immunodiffusion (ID) or complement-fixation (CF) test in 141 (47.3%) of 298 viral hepatitis patients. 35 cases were positive by the CF test only, while 2 cases by ID test only. However, CF test failed to detect HAA in a greater number of sera from 60 studied leprosy patients. CF HAA titers were highly correlated, but 15–25 times higher than ID titers. The increased sensitivity of the CF test especially in cases with low HAA titers may be the reason for the observed greater decline of the relative frequency of HAA, in relation to time of collection of sera after onset of jaundice, when sera were examined by ID rather than by CF test. In 39 (28.1%) cases, positive by the CF test, prozone reactions were observed at dilutions of 1 : 16 or higher, which stresses the necessity to examine a wide range of serum dilutions. The presence of anticomple-mentary activity had no diagnostic value and did not interfere substantially with the detection of HAA.