Amyloid and Chlamydia pneumoniae immunolabeling in AD tissue. Representative amyloid and C. pneumoniaeimmunolabeling detected in frontal (A, B) and temporal (C, D) sections of an AD brain. For amyloid labeling (brown color), two different anti-amyloid antibodies were used, (Sigma, panel A) and (Signet, panel C). Representative amyloid immunoreactivity, both extracellular plaques, including dense core plaques (A), and intracellular labeling (C) are revealed at a low magnification in order to appreciate the level of amyloid pathology. Likewise, C. pneumoniaeimmunoreactivity (magenta color) is evident at low magnification in both brain regions using two different monoclonal antibodies (Table 1, #5 panel B), and (Table 1, #3 panel D). Size bar A, B = 50 μm; C, D = 100 μm.