PHA and endotoxin stimulation of human lymphocytes separated by albumin density gradient centrifugation

Venous blood from eight healthy subjects was divided into four fractions on a discontinuous albumin density gradient. The percentage recovery of lymphocytes was 82.3%; the purity of the lymphocyte fractions was 83.6%. The lymphocytes were cultured with PHA and Endotoxin, and the samples were analysed after 24, 48, and 72 hours. After PHA stimulation immunoblasts appeared up to 59.3% in the cultures from the 19-21% albumin fraction. After Endotoxin stimulation the maximum (75.8%) was reached in the heavy (25-27% albumin) fraction. Thus, it is concluded that the lymphocytes which can be stimulated with both the mitogens have different densities, the PHA-stimulable T lymphocytes being ligther than the Endotoxin-stimulable B lymphocytes. It is also concluded that as a mitogen Endotoxin is equal to PHA.