Early transmembrane events in tumour cell responses observed by stopped-flow fluorometry

Early transmembrane events of tumour cells (mouse myeloma X5563 and lymphoma RDM4) after binding of a monoclonal antibody against mouse MHC antigen and a mitogenic lectin, Con A, were examined by stopped-flow fluorometry with 3 different fluorescent probes. The results showed that membrane fluidities of the cells increased first after binding of anti H-2Kk monoclonal antibody (11-4.1), then calcium was released from intracellular stores into the cytoplasma, and lastly calcium influx occurred from the external medium into the cytoplasma. While Con A only induced calcium influx from the external medium into the cytoplasma.