[Fundamental studies on serological diagnosis of amoebiasis. 2. Application of antigen of Entamoeba histolytica for complement fixation test to counterimmunoelectrophoresis; and clinical relevance of serological tests].

Antigen of Entamoeba histolytica for complement fixation (CF) test was applied to counterimmunoelectrophoresis (CIE), and the result was compared with that of CF test and enzyme-linked immunosorbent assay (ELISA) in regard to sensitivity and specificity. Besides, we studied antibody titers to E. histolytica in sera from acute and convalescent patients, and from patients with amoebic colitis and amoebic liver abscess. Sera used were from patients with amoebic colitis, amoebic liver abscess and uninfected control subjects. The CIE was less sensitive than the CF test and ELISA. Most CIE-negative samples had low CF and ELISA titers, but a few samples had higher CF and ELISA titers. On the other hand, all uninfected controls were negative by CIE and ELISA, and 98% were negative by the CF test. The level of antibodies tended to decrease with time after clinical recovery, but CF test and ELISA results remained positive in all patients 6 months after clinical cure. CIE converted negative in only one patient after 6 months. The level of antibodies of CF test and ELISA was significantly higher in amoebic liver abscess than amoebic colitis. These results suggested that all these three methods were so specific, and antibody titers by the CF test and ELISA were well correlated to clinical manifestations. The CIE with CF-antigen was less sensitive as compared with CF test or ELISA.