Evidence has been obtained that incubation of rat lymphocytes with neuraminidase, prior to intravenous transfusion into allogeneic or syngeneic recipients, alters the distribution of the cells. Many enzyme-treated lymphocytes initially become trapped in the liver, and there is a decrease in the selective accumulation of these cells in the lymph nodes and spleen. Subsequently, many enzyme-altered cells emigrate from the liver, concentrate in lymph nodes, and recirculate to the lymph. The results suggest that sialic acid constituents of the lymphocyte surface play a critical role in ensuring the normal distribution of these cells in the body. The findings also imply that reactions involving surface sialic acid can markedly alter the fate of lymphocytes without "killing" the cells.
Rat thoracic duct lymphocytes altered by trypsin in vitro do not circulate normally. At early intervals after transfusion of lymphocytes labeled with chromium-51 selective accumulation of radioactivity in the lymph nodes is abolished, while uptake in the spleen is not reduced. Later, the cells appear to "home" to lymph nodes and recirculate to the lymph.
Hemagglutination of turkey erythrocytes by Mycoplasma gallisepticum was inhibited by mucoproteins containing sialic acid, by sialic acid itself, and by treatment of the erythrocytes with neuraminidase. Neuraminidase treatment of the mucoprotein-rich inhibitors reduced or abolished their inhibitory activity. The findings indicate that sialic acid on the erythrocyte surface provides binding sites for Mycoplasma gallisepticum.
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