Neutrophils can regulate specific T cell response in lymph nodes

MALETTO B; ALIGNANI, D; LISCOVSKY, M; RANOCCHIA, R; GORLINO, C; CRESPO, MI; MORÓN, G; PISTORESI, MC

Rio de Janeiro. Brasil

Congreso; XIII Congreso Internacional de Inmunología.; 2007

Sociedad Internacional de Inmunología

A robust neutrophilia and a Th1 immune response are present after immunization withOVA plus Complete Freund?s Adjuvant (CFA). We show that when FITC-labeled OVA(OVA-FITC) was injected into the footpad of OVA/CFA immunized mice, the main OVAFITC+ cells recruited in draining popliteal lymph nodes (LN) were neutrophils. The OVAFITC+ neutrophil influx requires the presence of an antigen-specific response. Byevaluating the in vivo production of cytokines by neutrophils, we found that neutrophils present in LN exhibited a positive staining for TNF-α, and a slight expression of IFN-γ andIL-12 (28%, 8% and 10% respectively). To investigate the effect of neutrophils on theOVA-specific T-cell response, we injected OVA-FITC (day 0) in footpads in two groups ofOVA/CFA immunized mice: (I) treated with antibody anti-Gr-1 on days 2, 1, 0, +1, +2(mice depleted of neutrophils) and (II) treated with isotype control antibody. On day +3 theanimals were sacrificed and LN cells were challenged in vitro with OVA. LN cells fromneutrophil depleted mice secreted five times more IL-5 than LN cells from control mice (pg/ml: 1140±248 vs 242±39, p<0,005), whereas no difference was found in terms of IFN-γsecretion between both mice groups (pg/ml: 3401±1161 vs 2825±892). In conclusion, removal of neutrophils modified the cytokines balance in OVA-specific T-cell response.These data provide new evidence about the role played in vivo by neutrophils in adaptativeimmunity.