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-PALENCIA, MC

Río de Janeiro, Brasil

Congreso; 13th International Congress of Immunology, Río de Janeiro; 2007

International Union of Immunological Societies

A robust neutrophilia and a Th1 immune response are present after immunization with OVA 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 OVA-FITC+ cells recruited in draining popliteal lymph nodes (LN) were neutrophils. The OVA-FITC+ neutrophil influx requires the presence of an antigen-specific response. By evaluating the in vivo production of cytokines by neutrophils, we found that neutrophils present in LN exhibited a positive staining for TNF-a, and a slight expression of IFN-g and IL-12 (28%, 8% and 10% respectively). To investigate the effect of neutrophils on the OVA-specific T-cell response, we injected OVA-FITC (day 0) in footpads in two groups of OVA/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 the animals were sacrificed and LN cells were challenged in vitro with OVA. LN cells from neutrophil 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-g secretion 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 adaptative immunity.