CAPSAICIN-INDUCED INHIBITION OF MITOGEN AND INTERLEUKIN-2-STIMULATED T-CELL PROLIFERATION - ITS REVERSAL BY IN-VIVO SUBSTANCE-P ADMINISTRATION

The direct and indirect interaction between the nervous and the immune systems was evaluated in the rat using the neurotoxin capsaicin. Caps aicin treatment of neonatal rats (50 mg/kg at 2 days of age), results in a marked inhibition of mitogen and hrIL-2-induced cell proliferatio n both in the spleen and peripheral blood. Inhibition is already evide nt on day 15 after treatment and persists until day 90 in the spleen; at this time a return to control levels is observed in peripheral bloo d. The inhibition of proliferative response strongly correlates with a decreased number of CD5(+) and CD4(+) T cells as evaluated by immunof luorescence and FACS analysis. Moreover, continuous: in vivo SP admini stration stimulates mitogen and hrIL-2-induced proliferative response and completely reverts the capsaicin-induced inhibition of lymphocyte proliferation in the spleen.