title: Quantitation of intercellular binding strength by disruptive centrifugation: application to the analysis of adhesive interactions between P815 tumour cells and activated macrophages.
abstract: The cell binding assay described in the present paper provides a quantitative measurement of intercellular binding strengths between P815 mastocytoma cells and macrophages activated for cytotoxicity. Conjugates were submitted to a dislodgement force generated by centrifugation tending to remove radiolabelled probe cells from macrophages adhering to a glass support. Non-specific binding occurred between P815 cells and the glass support, but was negligible on siliconed coverslips. The adhesive interactions macrophage/glass were strong enough to resist up to about 1 X 10(-9) N, the maximal dislodgement force tested. Completion of conjugate formation was reached at 37 degrees C after 45 to 60 min and was inhibited at 4 degrees C or in Ca++-free medium. The strengths of intercellular bonds between P815 cells and macrophages varied from 7 X 10(-11) N (the minimal force applied) to more than 9 X 10(-10) N. No clear-cut separation between weak and strong interactions was observed when the centrifugation step was performed at 4 degrees C. In contrast, when centrifugation was carried out at 37 degrees C, a subpopulation of loosely bound tumour targets could be distinguished from more strongly bound P815 cells.
mesh_terms: D000818:Animals; D002460:Cell Line; D002498:Centrifugation / Q000379:methods; D003433:Crosses, Genetic; D007700:Kinetics; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D012515:Mast-Cell Sarcoma / Q000276:immunology*; D051379:Mice; D008811:Mice, Inbred DBA; D008815:Mice, Inbred Strains