Department of Microbiology and Immunology, and Department of Parasitology of the Faculty of Medicine of Ribeirão Preto, Department of Microbiology of the Faculty of Hygiene and Public Health of São Paulo, University of São Paulo, São Paulo, Brazil
A quantitative complement fixation test using a triple antigen, made up of cardiolipin No. 72 for syphilis, T. cruzi extract for Chagas' disease and a tubercle bacillus extract for tuberculosis and leprosy, is presented. Experimental work has been done to establish the basic principles governing the reaction by demonstrating that the specific systems react independently of the presence of other antigens.
Sera from 786 blood donors were tested against the triple antigen and against each one of the specific antigens, in complement fixation tests. The 599 sera that did not react with the triple antigen did not show any reactivity with the antigens for syphilis, tuberculosis-leprosy or Chagas' disease; no false negatives occurred with the triple antigen. The 103 sera which reacted with any one of the specific antigens, reacted also with the triple antigen. Four sera were anti-complementary, simulating “reaction” with the triple antigen; 76 sera gave “reaction” with the triple antigen but did not show any specific reaction in the tests for syphilis, Chagas' disease, tuberculosis or leprosy. These results could be due to the cumulative anticomplementary effect of these sera plus that of the antigens composing the triple antigen.
The preceding results indicate that a screen test employing the triple antigen should be used instead of the regular test for syphilis, in areas where syphilis, tuberculosis, leprosy, and Chagas' disease are endemic.