Isolation and buoyant density of Pneumocystis carinii in Percoll gradients.

A new gradient material, Percoll, a collodial suspension of silica particles covered with polyvinylpyrolidon, has been used to isolate Pneumocystis carinii from infected rat and human lung tissues. The specific gravity of Pneumocystis carinii was shown to be within the range of 1.018-1.062 g/ml with most pneumocysts within 1.033-1.049 g/ml.