Identification of albumin as the serum factor essential for the growth of activated human lymphocytes.
Albumin from human, bovine, or rabbit serum supported the growth of concanavalin A-stimulated human thymus-derived lymphocytes equally well. This activity was completely abolished by pepsin digestion. It was shown for bovine serum albumin that the albumin molecule itself, and neither an impurity nor a factor bound to albumin was essential for the growth of lymphocytes. This conclusion was based on observations that the growth-promoting activity could not be removed from albumin, and that the specific activity of albumin remained unaltered after the following procedures: molecular sieving at pH 7.5 at pH 3.0, and in 8 M urea at pH 6.6; ion exchange chromatography at pH 4.3 and in 8 M urea at pH 7.2; isoelectric focusing; charcoal treatment; acetone precipitation; and reduction with 2-mercaptoethanol in the presence of 8 M urea. Dimeric albumin was found to support growth of lymphocytes as well as monomeric albumin, and mercaptalbumin and non-mercaptalbumin were shown to have equal activity.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000187:drug effects / Q000502:physiology*; D010434:Pepsin A; D011817:Rabbits; D012709:Serum Albumin / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013045:Species Specificity
D012709:Serum Albumin; D003208:Concanavalin A; D012710:Serum Albumin, Bovine; D010434:Pepsin A