Effects of supernatants and lysates of polymorphonuclear leukocytes--lymphocyte mitogenic factors.

Rat polymorphonuclear leukocytes (PMNs), harvested from the site of a non-specific acute inflammatory reaction, liberated into culture fluids factors which not only enhanced the phytohaemagglutinin-induced proliferative response of thymocytes and lymph node cells, but were also mitogenic for these cells. This activity was associated with low molecular weight molecules (less than 10,000 daltons) and both these activities were also found in lysates of these PMNs. Our results suggest that inflammatory PMNs both contain and are able to release low molecular weight factors which can modulate lymphocyte function.