Types of Chemically Induced Lesions

Quiescent, perisinusoidal hepatic stellate cells (HSC) accumulate retinoids (vitamin A and its metabolites) in large cytoplasmic droplets and store about 80% of body s retinoids. However, these cells also express the muscle protein desmin and become activated to myofibroblasts upon exposure to hepatotoxicants. Activated HSC synthesize extracellular matrix proteins, especially when stimulated by cytokines and growth factors (see Section 28.4.2). 

Classification of chemically induced hepatotoxicity is primarily based upon pattern of incidence and histopathological morphology. Intrinsic hepatotoxic drugs demonstrate a broad incidence, dose-response relationship and will usually give similar results in humans and experimental animals. The incidence of liver damage from idiosyncratic hepatotoxicants is limited to susceptible individuals and results from hypersensitivity reactions or unusual metabolic conversions that can occur due to polymorphisms in drug metabolism genes (see Chapters 11 and 13). 

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