Figure 6.

Early bronchovascular infiltrates are diminished in CCR2^−/− mice infected with C. neoformans. CCR2^+/+ (A, C, E) and CCR2^−/− (B, D, F) mice were inoculated IT with C. neoformans and lungs were harvested at day 10 post-infection. Samples were processed for histological evaluation using H & E stain as described in Methods. (A, B) Photomicrographs (×100 magnification) depicting two spatially distinct regions of lung inflammation: bronchovascular infiltrates (BVI) and alveolar infiltrates (AI). Note the BVI adjacent to the airway (AW). BVI are more prominent in CCR2^+/+ mice (A) whereas they appear less developed in CCR2^−/− mice (B) despite the presence of substantial inflammation. At higher power, (C, D ×200) and (E, F ×400), note that BVI in CCR2^+/+ mice (C, E) contain predominantly mononuclear cells and lymphocytes that tightly pack regions surrounding small blood vessels. In contrast, BVI in CCR2^−/− mice (D, F) appear reduced both in cell number and density, whereas extracellular matrix in the perivascular space is increased. Individual C. neoformans and infected macrophages (arrow) are identified confirming the presence of infection in these regions.