Modulation of the in vivo immune response by selective depletion of neutrophils using a monoclonal antibody, RP-3. III. Enhancement by RP-3 treatment of the anti-sheep red blood cell plaque-forming cell response in rats.

Because recent work has shown that neutrophils produce various cytokines and are activated by these agents, this study was undertaken to examine neutrophil participation in immune networks. In our previous work, we demonstrated that delayed type hypersensitivity to SRBC and accompanying mononuclear leukocyte recruitment are inhibited in vivo by selective depletion of neutrophils using a mAb designated RP-3. To elucidate the function of these cells in Ab production, we assessed the splenic plaque-forming cell response to SRBC in a rat model through selective depletion of circulating neutrophils by RP-3. This depletion which occurred at the time of immunization resulted in an increase in the number of anti-SRBC Ab producing cells, as determined by the direct and indirect plaque-forming cell response. This phenomenon was observed only when the Ag was administered i.p. and not with i.v. immunization. These results suggest that neutrophils suppress Ab production in certain situations.