Antibody-dependent cell-mediated cytolysis (ADCC) with antibody-coated effectors: new methods for enhancing antibody binding and cytolysis.

When P388D1 cells are incubated with anti-TNP IgG antibody and centrifuged through a mixture of dibutylphthalate and bis-(2-ethylhexyl)phthalate (1.5:1), large amounts of antibody remain cell bound for at least 20 hr after washing. Incubating cells with antibody in various concentrations of polyethylene glycol also enhances antibody binding compared with control cells incubated with antibody alone. P388D1 cells coated with anti-TNP antibody are potent killers of TNP-conjugated chicken erythrocytes (not coated with antibody). The cytolytic activity increases in proportion to the amount of antibody bound by the effector cells. Lysis is antibody dependent and hapten inhibitable. When mediated by antibody-coated effectors, lysis is less suceptible to inhibition by aggregated IgG than lysis of antibody-coated cells mediated by untreated effector cells.