Two host responses to TB Tissue-damaging response Delayed-type hypersensitivity (dth reaction to various bacillary antigens It destroys nonactivated macrophages that contain multiplying bacilli Basis of the ppd skin test Macrophage-activating response A cell-mediated phenomenon resulting in the activation of macrophages that are capable of killing and digesting tubercle bacilli MBBS project, Zhongshan Hospital
MBBS project, Zhongshan Hospital Two host responses to TB • Tissue-damaging response — Delayed-type hypersensitivity (DTH) reaction to various bacillary antigens — It destroys nonactivated macrophages that contain multiplying bacilli — Basis of the PPD skin test • Macrophage-activating response — A cell-mediated phenomenon resulting in the activation of macrophages that are capable of killing and digesting tubercle bacilli
Two types of cells are essential in the formation of tB Macrophages: directly phagocytize tB and processing and presenting antigens to T lymphocyte T lymphocytes(CD4+): induce protection through the production of lymphokines MBBS project, Zhongshan Hospital
MBBS project, Zhongshan Hospital Two types of cells are essential in the formation of TB • Macrophages: directly phagocytize TB and processing and presenting antigens to T lymphocyte • T lymphocytes(CD4+): induce protection through the production of lymphokines
Tuberculosis granuloma Rounded tight collection of chronic inflammatory cells Central caseous necrosis Active macrophages epithelioid cells · Outer layer of lymphocytes, plasma cells fibroblasts Langhans giant cells Multinucleate giant cell joined epithelioid cells MBBS project, Zhongshan Hospital
MBBS project, Zhongshan Hospital Tuberculosis Granuloma • Rounded tight collection of chronic inflammatory cells. • Central Caseous necrosis. • Active macrophages - epithelioid cells. • Outer layer of lymphocytes, plasma cells & fibroblasts. • Langhans giant cells – joined epithelioid cells
Tuberculosis granuloma 浮 37 Bacterial entry; T Lymphocytes, macrophages, epitheloid cells. Proliferation: Central Necrosis: Giant cell formation Fibrosis. MBBS project, Zhongshan Hospital
MBBS project, Zhongshan Hospital Tuberculosis Granuloma Bacterial entry; T Lymphocytes, macrophages, epitheloid cells. ;Proliferation; Central Necrosis; Giant cell formation; Fibrosis
Disease outcomes Timely and proper chemotherapy immuno competent Lesion resolved Fibrosis and calcification; bacilli may remain dormant within macrophages or in the necrotic materials Cured Improper use of drug, immuno-compromised Caseous necrosis Liquifaction Cavity Disease dissemination through bronchi or blood Bacilli multiply MBBS project, Zhongshan Hospital
MBBS project, Zhongshan Hospital Disease outcomes • Timely and proper chemotherapy, immunocompetent — Lesion resolved — Fibrosis and calcification: bacilli may remain dormant within macrophages or in the necrotic materials — Cured • Improper use of drug, immuno-compromised — Caseous necrosis — Liquifaction — Cavity — Disease dissemination: through bronchi or blood — Bacilli multiply