Use of microcalorimetry in analysing the kinetics of ADCC

Microcalorimetry was found to be a useful technique for the demonstration of antibody-dependent cellular cytotoxicity (ADCC) against human melanoma cells mediated by a heterologous rabbit antiserum and two monoclonal antibodies in combination with human peripheral blood lymphocytes as effector cells. The rabbit antiserum and the monoclonal IgG3 antibody 2B2 directed against the GD3 ganglioside expressed cell-inhibitory effects resulting in a decreased heat production rate over 2-18 h of incubation. The 4.2 monoclonal IgM antibody to GD3 had no similar cell-inhibitory effect. In contrast, the 4.2 antibody expressed a much stronger effect than 2B2 in tests for complement-dependent cytotoxicity. The kinetics of these effects were quite reproducible. It is concluded that microcalorimetry is a sensitive and particularly suitable method for the analysis of cytotoxicity kinetics.