G213 reacted with PMNs located at the core of granulomas. (A-B) Sections of lungs obtained from the BCG-challenged guinea pig granuloma model were labeled with either isotype-matched negative control mAb (A) or G213 mAb (B), and HRP-DAB-based detection was performed. Sections were counterstained with hematoxylin. Scale bars, 100 μm. (C) A magnified view of G213-reactive cells (arrowheads) observed in panel B indicated that the stained cells were PMNs. Scale bar, 5 μm. (D) An immunoelectron micrograph of PMN cells positively labeled with G213 is shown. Gold particles representing the expression of the G213 antigen are indicated with arrowheads. Scale bar, 2 μm. (E-F) Paraffin-embedded lung sections derived from M tuberculosis–infected guinea pigs were labeled with either isotype-matched negative control mAb (E) or G213 mAb (F), and HRP-DAB-based detection was performed. G213-positive cells were prominently found in the central area of pathological granulomas. Scale bars, 1 mm. (G) A magnified view of a G213-positive cell (arrowhead) observed in panel F exhibited a typical PMN morphology. Scale bar, 5 μm.