Leprosy is a disease caused by the intracellular bacterium Mycobacterium leprae, which infects macrophages and replicates in their phagosomes. Human patients with leprosy have a persistent infection of the mycobacteria, as their immune systems are unable to complete eradicate the pathogen. Furthermore, two different forms of the disease have been identified. Some patients have many skin lesions containing a large number of bacteria with little inflammatory response. This is the very disfiguring form of the disease, and is known as lepromatous leprosy. In other patients, few skin lesions and only occasional bacteria are observed, and the skin lesions are accompanied by a robust inflammatory response. These patients have the form of the disease known as tuberculoid leprosy. If one examined a skin biopsy from a patient with tuberculoid leprosy, one would expect to see:
A) A large influx of neutrophils and other granulocytes
B) A widespread occurrence of tissue necrosis
C) A substantial number of granulomas
D) Evidence of large numbers of dead or dying mycobacteria
E) A large number of skin epithelial cells with intracellular bacteria

Question

Quizplus · Accepted Answer

Patients with tuberculoid leprosy have a robust inflammatory response, which leads to the formation of granulomas in the skin lesions. These granulomas are aggregates of immune cells, such as macrophages, neutrophils, and lymphocytes, that attempt to contain and eliminate the mycobacteria. Thus, a skin biopsy from a patient with tuberculoid leprosy would show a substantial number of granulomas. The other choices are not correct because neutrophils and tissue necrosis are not typically seen in this form of the disease, and there would not be evidence of large numbers of dead or dying mycobacteria because the immune system is attempting to contain the infection. Finally, skin epithelial cells would not contain the intracellular bacterium that causes leprosy.

Leprosy Is a Disease Caused by the Intracellular Bacterium Mycobacterium