Abstract
Working in cooperation with the Research Committee of the National Tuberculosis Association, Drs. F. R. Sabin, C. E. Forkner, and the writer, in this laboratory, have been assaying biologically during the past 3 years the various chemical fractions obtained from the tubercle bacillus by Drs. T. B. Johnson and R. J. Anderson of the Sterling Chemistry Laboratory, Yale University. The investigation includes a parallel study of the chemistry and biology of several members of the acid-fast group of bacteria grown in large quantities by Mulford and Parke, Davis under standard conditions on Long's synthetic media. It has been found that the phosphatide fraction isolated from the tubercle bacillus by Anderson contains an active principle capable of stimulating and maturing monocytes and epithelioid cells. This phosphatide fraction from the human tubercle bacillus H-37 has been shown by Pinner to act as a complete antigen when given intravenously in animals, as proven by precipitin and complement fixation tests. We have confirmed this finding with reference to the precipitin reaction. Readings are made after 5 minutes at room temperature, after 2 hours at 38° C., and after 24 hours in the ice-box. Pseudo-positive reactions are thus avoided. Considerable experience in reading the tests is necessary for accurate determinations. Variations in hydrogen ion concentration, pH 2.5 to 6.02, have had no influence on the reaction. The sera of normal rabbits have been found to give a positive precipitin test in low dilutions only, 1-20 with dilutions of a 1% antigen, or with a fixed antigen with only the undiluted serum. The exceptional rabbit direct from stock showing higher titres is now discarded for all experimental work in fraction testing and other studies on tuberculosis in this laboratory. There is some evidence that small variations in the phosphatide precipitin titre may accompany a non-tuberculous monocytosis in blood and connective tissues.
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