Cytokine recall essay. Isolated total lung tissue cells were cultured for 24 hours with the indicated doses of OVA and cytokine release was measured. (A) TNF, (B) IL-6, (C) MCP-1, and (D) IL-5 release (on a per-cell basis) in response to OVA-stimulation of isolated lung tissue inflammatory cells. There is no statistically significant difference in OVA-specific cytokine release between wt and CD34^−/− mice (n=3 independent experiments).