ITGA4 and systemic inflammatory response syndrome: The CD49d+CD11b− N1 neutrophils isolated from SCIDbg mice with mild systemic inflammatory response syndrome (SIRS) secrete the cytokine IL-12 and chemokine CCL3, while CD49d−CD11b+ N2 neutrophils isolated from SCIDbg mice with severe SIRS mainly produce IL-10 and CCL2.