Neutrophils promote 6-sulfo LacNAc dendritic cell (slanDC) survival

There is increasing evidence supporting the notion that neutrophils and other leukocytes establish cooperative actions in regulating innate and adaptive immune re-sponses. In such a context, we have shown recently that human neutrophils amplify NK cell/slanDC-medi-ated cytokine production by directly costimulating IFN- production by NK cells, as well as by potentiating IL-12p70 release by slanDCs via CD18/ICAM-1 interac-tions. To gain more insights into the molecular bases of the neutrophil-mediated cytokine potentiation by NK cells and slanDCs under coculture conditions, we now report that neutrophils efficaciously maintain slanDC survival by contact-dependent mechanisms. Such a phenomenon occurs in the absence or presence of NK cells, which, in the presence of LPS and IL-2 or the IL-15/IL-18 combination, accelerates slanDC apoptosis significantly. Noteworthy, ICAM-1- and CD18-neutral-izing antibodies, previously shown to suppress IL-12p70 production by slanDCs and consequently, IFN- by NK cells under similar experimental conditions, did not min-imally alter the neutrophil-mediated prosurvival effect on slanDCs. Altogether, data not only expand our knowledge on the interactions between human neutro-phils and slanDCs but also prove that neutrophil-medi-ated promotion of slanDC survival and potentiation of slanDC-derived IL-12p70 occur via different mecha-nisms. J. Leukoc. Biol. 94: 000–000; 2013