Fig. 3.

Histopathology of Mtb-infected rabbit lungs 12 weeks post infection (8 weeks of treatment). (a, b and c) Representative images of H&E (a and b) or AFB (c) stained lung section from untreated rabbits. Well demarcated, large confluent granulomas with central necrosis and mineralization, surrounded by macrophages and many lymphocytes can be seen. High numbers of acid-fast bacilli (arrowheads) were also found in these granulomas. (d, e and f) Representative images of H&E (d and e) or AFB (f) stained lung section from rabbits treated with CC-11050 only. Well demarcated, large lesions with central necrosis surrounded by multiple epithelioid macrophages and less lymphocytes can be seen. Very few acid-fast bacilli are noted in these granulomas. (g, h and i) Representative images of H&E (g and h) or AFB (i) stained lung section from rabbits treated with INH only. Granulomas with central area of extensive necrosis and mineralization, surrounded by foamy macrophages and lymphocytes can be seen. Very few AFB-positive organisms were found in these granulomas. (j, k and l) Representative images of H&E (j and k) or AFB (l) stained lung section from rabbits treated with the combination of INH and CC-11050. Very few, well demarcated, non-necrotic small granulomas, undergoing resorption can be seen. No clearly visible AFB-positive organisms were observed in these granulomas. Figures a, d, g and j were photographed at 4 × (Scale bar = 500 μm) and b, e, h and k at 40 × (Scale bar = 50 μm) magnification, respectively. Sections c, f, i and l (acid-fast stain) were photographed at 80 × (Scale bar = 25 μm) magnifications.