ASSAY OF TUBERCULIN ANTIBODY BY MEANS OF THE PHOTOMETRIC HEMAGGREGATION TEST H. COMPARATIVE TITRATION OF ANTIBODY BY HEMAGGREGATION TEST AND BY CONVENTIONAL TECHNIQUES

antibody by means of the photometric hemaggregation test. II. Comparative titration of antibody by hemaggregation test and by conventional techniques. Amer. J. Epidemiol., 1968, 87: 339-348.—A series of human and of animal sera were tested comparatively for tuberculin antibody both by the photometric hemaggregation test (AOTU and APTU titers) and by conventional techniques. The results obtained indicate that the AOTU titers reflect primarily E/OT agglutina-ting antibody, while APTU titers measure ET/PPD antibody. In comparison to antibody titration by means of conventional tests, the novel technique was found to be about 15 to 28 times more sensitive. In a preceding publication (1), a novel technique for the titration of tuberculin antibody has been described. This tech-nique is based on the empirical finding that tuberculin inhibits specifically (2, 3) the aggregation of trypsin treated human erythrocytes suspended in a buffered glucose medium of low ionic strength at low pH, and that this "hemaggrega-tion inhibiting " (HI) (4) activity of tuberculin is neutralized by the additio