Induction of lymphocyte proliferation by antigen-pulsed human neutrophils.

We have investigated whether purified antigen-pulsed human neutrophils can induce a proliferative response in purified resting blood lymphocytes. Neutrophils were pulsed with soluble tetanus toxoid (dose range 25-250 Lf/ml) and co-cultured with autologous lymphocytes that had been depleted of MHC class II expressing cells. The antigen-pulsed neutrophils induced an increase of lymphocyte proliferation which was dependent on the antigen dose and the neutrophil/lymphocyte ratios. Neutrophils were less potent than autologous monocytes in stimulating lymphocyte proliferation. Blocking with a monoclonal antibody to a common determinant of the human MHC class II complex failed to reduce the lymphoproliferative effects and allogenic antigen-pulsed neutrophils were also able to elicit lymphocyte proliferation similar to autologous neutrophils. We conclude that antigen-pulsed neutrophils are able to induce lymphocyte proliferation in a non-MHC-restricted fashion.