A LYMPHOCYTOPENIA PRODUCING FACTOR FROM NOCARDIA

Nine strains of bacteria, isolated from the soil and provisionally classified as Nocardia, have been found to elicit a profound lymphocytopenia upon injection in heavy suspension into rabbits. Isolation of the haematologically active principle has been achieved by the tryptic digestion of whole cells, followed by centrifugation and prolonged dialysis of the supernatant fluid. The isolated material is of high potency, 1 mgm. producing in the rabbit a haematological response qualitatively identical to that obtained with whole cells and only slightly less in degree than that obtained with 100 mgm. of the lyophilized intact cells. On the basis of qualitative biochemical tests and paper chromatographic analysis, the active principle is believed to be a polysaccharide and was found to consist of reducing sugars and a non-reducing fraction, a "uronic" or "onic" acid, which gave the reactions characteristic of a sugar acid. The haematological activity and the chemical nature of the material suggests that this compound belongs to the large group of "pyrogenic" polysaccharides.