IMMUNOBIOLOGY Presence of neutrophil-bearing antigen in lymphoid organs of immune mice

Neutrophils play a crucial early role during the innate response, but little is known about their possible contribution when an adaptive immune response is installed. A robust neutrophilia and a T helper 1 (Th1) immune response are present after immunization with Complete Freund Adjuvant (CFA). We show that when FITC-labeled OVA was injected into the footpad of OVA/CFA immunized mice, the main OVAFITC cells recruited in draining popliteal lymph nodes (LNs) were neutrophils, with most of them arriving at the LN by means of lymphatic vessels. The development of this OVA-FITC neutrophil influx requires an immune response against OVA. The OVA-FITC neutrophils present in LNs displayed mainly intracellular TNF, and their depletion resulted in an increase in the specific IL-5 levels. These data provide new evidence about the role played by neutrophils in vivo in adaptive immunity. (Blood. 2006;108:3094-3102)