FIG. 4.

Histopathology induced by intranasal SEB challenge. Age-matched HLA-DR3 transgenic mice were challenged intranasally with PBS or SEB (20, 200, or 2,000 ng) on days 0, 3, and 6. After harvest of BAL fluids on day 8, lungs were collected in buffered formaldehyde and embedded in paraffin. Thin sections were stained in hematoxylin and eosin (A, C, and F), or the deparaffinized sections were stained with anti-MBP antibody (B, D, and G). (A and B) PBS-treated mice; (C to E) 20 ng SEB; (F and G) 2,000 ng of SEB. (E) Lung section from mouse that received 20 ng of SEB treated with preimmune rabbit serum followed by fluorescein isothiocyanate-conjugated secondary anti-rabbit antibody showing the specificity of the anti-MBP antibody. Magnification, ×160.