Relationship between concanavalin A-induced agglutinability of murine leukemia cells and their propensity to form heterotypic aggregates with syngeneic lymphoid cells

Abstract

The agglutinabilities of the murine leukemia cell lines L1210, P388, and C1498 were determined in the presence of concanavalin A (Con A) by a quantitative cytoagglutination assay. The propensity of these cells to form heterotypic aggregates with normal syngeneic spleen cells, those obtained from mice carrying the respective leukemias in ascitic form, and syngeneic lung cells also were determined. Con A caused agglutination of all five types of leukemia cells and the resulting agglutination patterns had certain characteristics. Threshold concentrations of Con A, below which no significant cytoagglutination occurred, were very low. A steady increase in zeta, a previously defined index of agglutination that simultaneously takes into account the number of free cells and the number and size of the aggregates, was observed with increasing concentrations of Con A until a plateau was reached at 25-50 microgram/ml and this extended over a wide range of lectin concentrations (50-1,000 micrograms/ml). Self-aggregation of leukemia cells was not observed, and their propensity to form heterotypic aggregates with syngeneic lung cells was negligible. However, all leukemia cell lines formed measurable aggregates with spleen cells from both normal and leukemia-bearing mice; these aggregates usually reached a maximum plateau between 30 and 35 minutes of incubation and remained constant thereafter. Aggregation of leukemia cells with spleen cells from leukemic mice always was greater than that with spleen cells from normal mice. Con A agglutinability of leukemia cells was correlated with their propensity to form heterotypic aggregates, which suggests that Con A agglutinability of leukemia cells was correlated with their propensity to form heterotypic aggregates, which suggests that Con A receptor carbohydrate moieties may be involved in the intercellular adhesion leading to heterotypic aggregate formation.