Immune-indian ink method for detection of hepatitis A associated antigen and antibody

TIndian-ink grains coated with commercial gamma globulin (immune-Indian-ink) were agglutinated by 3 percent of sera from healthy volunteer blood donors; by 4 percent of those from hospital staff in contact with patients suffering from hepatitis; and by 10 percent of those from patients with viral diseases other than hepatitis, In contrast, the rate of positive reactions was 86 percent in the case of sera taken from patients in the acute phase of an illness diagnosed as hepatitis A on the basis of epidemiological and clinical data. Investigation of serum samples taken serially from patients positive in the acute phase of illness revealed that the immune-Indian-ink agglutinating factor does not persist for long in majority of cases. Two months after discharge from the hospital it was present in 18 percent of the patients only. The reaction proved negative when a limited number of cases diagnosed as hepatitis B were investigated. The immune-Indian-ink agglutinating factor was inhibited by all but one of 36 sera taken in the convalescent phase from patients with a diagnosis of hepatitis A. Some sera displaying agglutination with immune-Indian-ink gave a reaction with uncoated Indian-ink, too. Efforts to free the sera from non-specific agglutinating factor by starch-block electrophoresis have led to partial success. Fractionation on Sephadex G-200 columns suggested that in molecular weight (or particle size) the immune-Indian-ink agglutinating factor is smaller than HBsAg and larger than the non-specific agglutinating factor. On the basis of these results it is assumed that the immune-tindian-ink reaction is suitable for detecting an antigen tentatively called IH chi Ag and its antibody (IH chi Ab) specific to hepatitis A.