VITAL STAINING OF THE CONNECTIVE TISSUES

Localization of antigen in tissue cells; cellular distribution of pneumococcal polysaccharides types II and III in the mouse

The cytological distribution of the pneumococcal polysaccharides, types II and III, was followed in the tissues of the mouse. The most constant and striking concentrations of these polysaccharides were found in the cells of the reticulo-endothelial system, the ordinary capillary endothelium, and fibroblasts throughout the body. In addition, polysaccharide was detected in monocytes and lymphocytes, hepatic cells, cardiac and smooth muscle cells, uterine epithelium, and in steroid-forming cells in the adrenal cortex, testis, and ovary. Studies of the persistence of polysaccharide, type III, in the tissues were carried out after an injection of 4.0 mg. The polysaccharide remained for at least 75 days in the macrophages of lymphoid organs, the Kupffer cells of the liver, the interstitial macrophages in the myocardium, the lung septal cells, the capillary endothelium, and the renal glomerulus. After a single injection of 8 mg., it persisted for at least 6 months in the macrophages of the spleen, liver, and heart and in the endothelium of peritubular capillaries in the kidney. The smallest dose of polysaccharide which produced detectable amounts in any cells 24 hours after injection was 0.03 mg. The distribution of polysaccharide is compared with that of acid vital dyes and suspensoids, and the significance of its fixation in relation to its antigenicity and possible toxicity in mice is discussed.