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Agglutination and surface properties of seperated teratocarcinoma
Specific subpopulations of 129/J mouse teratocarcinoma cells were isolated by velocity sedimentation in shallow density gradients using unit gravity and centrifugal force. The subpopulations were examined with perspective plots generated using a computer program. These plots permitted 360° rotation of the horizontal axis making it possible to examine the symmetry of the major cell populations. The teratocarcinoma consistently separated into two major populations of cells: "large" and "small" cells. The separated populations were examined for their agglutinating properties in the presence of the lectins concanavalin A (ConA) and wheat germ agglutinin (WGA). Although the two populations bound both lectins, only the large cells appreciably agglutinated in the presence of ConA. Slight agglutination was mediated by WGA in both populations. Forty different samples of mixed populations of teratocarcinoma were treated with flourescein-conjugated ConA and examined with a flourescence microscope to observe lectin receptor patterns. ConA induced surface receptor clustering in the large cell population only. Receptor sites remained diffuse in the small cell population. Cells were also examined with the scanning electron microscope and surface differences between the two populations were detected. This study demonstrates the existence of at least two cell populations within the teratocarcinoma tumor. In addition, a method for-separating these populations in large volumes has been developed. Finally, differences in lectin receptor mobility and lectin mediated agglutination have been demonstrated in the specific cell populations.