The Hæmagglutination Test in Tuberculosis

IN establishing the diagnosis of tuberculosis, the demonstration of the infecting agent by microscopical and modern culture techniques is the method of choice. Many attempts have also been made to establish a diagnosis by such serological means as precipitation or the fixation of complement, but all these methods have proved unsatisfactory, and none are in common use. In 1948, Middlebrook and Dubos introduced a new technique-a haemagglu-tination test-to demonstrate antibodies which may be present during the course of infection. In this method washed sheep red cells were sensitised with an extract of a culture of tubercle bacilli H37. They showed that sheep red blood cells sensitised in this way were agglutinated by even small amounts of anti-bodies in the patient's serum. They claimed that the test was specific for tuberculosis, and suggested that it might be applied in clinical diagnosis. The sera of six cases of patients known to be suffering from tuberculosis gave positive results in a dilution of 1: 8 or over. Using modifications of this technique, Gerney-Rieux and Tacquet (1950) and Smith and Scott (1950) showed that 80 per cent of patients wvith active tuberculosis had positive hemagglutinin titres of 1: 8 or over. Higher figures of 92.3 per cent positive titres were published by Rothbard, Dooneif and Hite (19050). Sohier, Juillard and lFrimberger (1950) with 8 positive out of 17 cases of active pulmonary tuberculosis, and Hilson and Elek (1951) with only one-third of their tuberculous patients giving positive results, found the test less useful. These workers also found(l that a small percentage of healthy controls gave a positive test. In this investigation, the haemagglutination test has been applied in a series of tuberculous patients, including tuberculous meningitis. An attempt was also made to establish the relationship, if any, between the possession of haemagglu-tinating antibodies and the presence or absence of a positive Mantoux skin reaction. rECHNIQUE. The technique used by Smith and Scott (1950) for demonstrating halmagglu-tinating antibodies was modified as follows: Sheep red blood cells were washed repeatedly and 0.1 ml. of the packed cells was sensitised with 6.0 ml. of a 1: 7j dilution of double strength deglycerinated old tuberculin (B. and XNr.) by incubating at 37°C in a water bath for two hours. The patient's serum was inactivated at 65'C for three minutes and freed from heterophile antibodies by absorption with sheep red cells. l'o 0.2 ml. of doubling dilutions of the …