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Concanavalin a derivatives and cell agglutination
Agglutination of S-180 ascites tumor cells mediated by Concanavalin A (ConA) and biologically active succinyl and acetyl ConA derivatives was quantitatively measured and compared, using an electronic particle counter assay. ConA causes agglutination of tumor cells in vitro. Compared to ConA, succinyl ConA (SConA) and acetyl ConA (AConA) cause a substantial reduction in agglutination. Agglutination mediated by ConA, SConA and AConA was affected by pretreatment of the tumor cells with cytochalasin B (cyto B) and colchicine. Cyto B causes inhibition of cellular microfilaments while colchicine causes inhibition of microtubules. ConA mediated agglutination of cyto B pretreated tumor cells was greater than ConA mediated agglutination of untreated cells. Agglutination mediated by SConA and AConA contrasted sharply from the ConA profile. SConA and AConA mediated agglutination of cyto B pretreated tumor cells was less than SConA and AConA mediated agglutination of untreated cells. ConA mediated agglutination of tumor cells was not substantially changed by colchicine pretreatment; however, reduced agglutination of colchicine pretreated tumor cells with SConA and AConA was observed. Inhibition of protein synthesis with cycloheximide does not appear to affect agglutination, while reduction in temperature decreases agglutination. This decrease in agglutination may be related to reduced ConA receptor site clustering which is necessary for effective intercellular connections. These results indicate that derivatized ConA may have a reduced binding affinity for ConA receptor sites on the cell surface. This may reduce the clustering of ConA receptor sites and therefore reduce agglutination of these cells. Although microfilaments and microtubules have not been shown as fine structural elements in these cells, the results suggest that ConA receptor sites on the cell surface may be associated with microfilaments and microtubules.