[Restoration of ability to proliferate and produce mitogenic factor by human lymphocytes in a serum-free medium following their purification].

The response of purified and "non-purified" human blood lymphocytes to phytoheamagglutinin (PHA) and their capacity to produce mitogenic factor upon PHA-stimulation in protein-free and serum-containing culture medium were investigated. Non-purified lymphocytes lost the capacity to react to the stimulation with PHA and to produce the mitogenic factor in protein-free culture medium. Purification of lymphocytes on the density gradient or passing them through a column made them resume their response to PHA and their capacity to produce the mitogenic factor in protein-free medium. It is assumed that the inhibition of the response to PHA in protein-free culture medium may be caused by polymorphonuclear leucocytes.