Single cell analysis of changes in electrokinetic properties of a growing ascitic tumor

An ascitic tumor (SEWA) induced by polyoma virus in A.SW mice was analyzed in vivo as well as in vitro with regard to the electrophoretic mobility (EPM) which may be considered as a reliable criterion of surface charge. After the i.p. transplantation of 10(5) cells, the EPM decreased up to 14th day. Then, the mobility gradually increased with the age of the tumor. In the first phase of tumor growth, we have considered the possibility that immunoglobulin cell coating may be responsible for the decrease in EPM. In the late phase of SEWA growth, the progressive increase in EPM might be due to a rearrangement of sialic acids on the outer part of the cell membrane.