Retarded clearance of macroaggregated albumin from the lung of asthmatic patients.

This agent ( 2 ‘,,‘/mi) disrupts microfilaments in many cell types including the AM.2 It does not impair microtubular morphology. Quantitative bacteriologic methods demonstrate diminished uptake of live Staphylococcus aureus from shaking bacteriaAM suspensions in the presence of cytochalasin B. These effects are associated with striking diminution of ‘4C02 production from ‘4C-1-glucose and ‘4C-6-glucose ( 77 percent and 42 percent respectively in AM exposed to killed Staphylococcus epidermidis ) . Cytochalasin B did not affect ‘4CO2 production from ‘ 4C1 -pyruvate, ‘4C1 -acetate or ‘4C-1-4 succinate, nor impair the activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconic acid debydrogenase. Further, the effects are reversible by washing out the cytochalasin B. The association of diminished bacterial ingestion and disruption of the microfilaments suggests that the latter serve as actin-like contractile proteills in the ingestion process. The diminution of CO2 formation from labelled glucose may possibly arise froiii a combination of diminished ingestion and impaired glucose transport. The latter possibility is suggested by preliminary evidence indicating that the uptake by AM of the transportable but nonmetabolized glucose analogue, 2-deoxyglucose is inhibited l)y 2 y/ml of cytochalasin B.