Specific circulating immune complexes in amoebic liver abscess.

A micro enzyme-linked immunosorbent assay was used to detect the presence of amoebic antigen in polyethylene-glycol-precipitated circulating immune complexes (CIC). A cutoff dilution of greater than 1:160 for the precipitates was taken to be of clinical significance. Among the patients with amoebic liver abscess, 93% (14 of 15 confirmed cases) had indications of amoebic antigen in CIC. In 57% of the suspected cases of amoebic liver abscess, amoebic antigen could be detected in CIC. The specificity of the technique for the demonstration of specific amoebic antigen is indicated by the undetectable levels of amoebic antigen in CIC in serum samples from nine cases of nonamoebic hepatic diseases and 10 apparently healthy subjects. It is thus believed that the specific diagnosis of an individual case of amoebic liver abscess can be made by demonstrating specific amoebic antigen in CIC.