Figure 4

The effects of cyclophosphamide (CPA) or dexamethasone (DEX) on the IL-13 (+) expressing cells. Rats were pretreated intratracheally with saline (Fig. A, E ; n = 8), CPA (Fig. C, E ; n = 6) or DEX (Fig. D, E ; n = 6) prior to treatment with TiO₂ Eight rats were treated with TiO₂ alone (Fig. B, E ; n = 8) as described in Methods. At 48 h post-treatment, IL-13 (+) cells are stained brown whereas toluidine blue (+) mast cells are stained dark purple. Note that saline – treated group contained little or no IL-13 (+) cells (Aa) in spite of the presence of mast cells (Ab). TiO₂-treated group showed significantly increasing numbers of mast cells when compared with sham group (E) and the mast cells (Ba) showed strong positivity for IL-13 protein (Bb). CPA pretreatment did not affect the TiO₂ induced-increase in the number of IL-13 (+) cells (Ca) or mast cells (Cb & E). On the other hand, DEX pretreatment significantly decreased the number of mast cells (Db & E) and reduced the IL-13 (+) cells (Da). * p < 0.05 as compared with saline treated group, † p < 0.05 as compared with TiO₂ treated group.