The Mallory body: theories on development and pathological significance (Part 2 of a literature survey).

Drawing on data from a previously published literature survey on the clinical and experimental epidemiology of the Mallory body, we discuss current theories on its development in a pro et contra manner. Conclusions have been largely left open to the interpretations of the reader because many are still speculative. The main results of this study characterize Mallory bodies as stereotypical histological byproducts to diverse hepatic injuries (mostly alcohol associated) of questionable pathogenic importance. The temporal characteristics of Mallory bodies cast doubt on their role in hepatic neoplasia both as a disease marker and a causative agent, and prognosis studies suggest that they may be considered preterminal markers in some nonalcoholic liver diseases but remain prognostically unimportant in most studies on alcoholic patients. By similar line of inquiry, no consistent relationships may be found with disease severity or duration in alcoholic liver diseases. The roles of vitamin A deficiency and protein-calorie malnutrition are circumstantial. Drugs known to have calcium-antagonist properties and the physiological characteristics of the stress-response protein ubiquitin support the concept of defective protein systems in Mallory body pathogenesis. Disproportionate hepatic copper accumulation seems both epidemiologically and topographically associated with Mallory bodies, but these connections are largely unsupported by exposure studies. Many arguments still downplay the importance of uncoordinated changes in hepatic oxygen delivery and consumption, but ischemia-reperfusion studies suggest a role of oxygen-derived free radicals in the liver injuries under scrutiny. Finally, the role of Mallory bodies in the control system of hepatocyte function is addressed, and indirect evidence lends credence to a cybernetic approach in future study designs. It is reasonable to assume that different elements of a multifactorial setting operate with varying intensity over time as this may account for some of the controversies that exist. In conclusion, the biological significance of Mallory bodies is still mystery. It is not known whether Mallory bodies represent an epiphenomenon or play a role themselves in the initiation and continuation of liver damage.