Fig 2. Splenic macrophages produce histamine by interacting with antigen-specific Th2 cells through the antigen.

Splenic macrophages (WT or Hdc^-/-macrophages) and OVA-Th2 cells (WT or Hdc^-/-OVA-Th2 cells) were co-cultured in the presence or absence of OVApep for 24 h, and then histamine production was measured in the culture supernatants. Pooled data from 3 independent experiments are shown by means±S.D., n = 6–10. **P<0.01, N.S. not significant.