Biometals in skin and sera of leprosy patients and their correlation to trace element contents of M. leprae and histological types of the disease; a comparative study with cutaneous tuberculosis.

The present study has provided information on the biometal contents of killed and dried Mycobacterium leprae as well as dermal granulomas induced by the invading mycobacteria in various histological types of leprosy patients. For comparison, the biometal contents of the contralateral leprosy-unaffected skin of the same patients also were measured. The study also reports changes of serum levels of the biometals in these patients which were compared with those in healthy control subjects and patients with skin tuberculosis. These data show that M. leprae is rich in zinc. During the course of the evolution of the disease there is gross alteration of the dynamics of the inflammatory cell population that infiltrates into leprosy granulomas, resulting in the alterations of trace element contents of the disease-affected skin lesions. Interestingly, the changes of the biometal contents in the granulomas of the patients with skin tuberculosis are similar to those in leprosy patients. It is postulated that the significant decrease of the contents of copper, zinc, iron, calcium and magnesium in the disease-affected skin in comparison to that of the contralateral healthy skin is a local effect, perhaps due to erosion or influx of biometal-deficient inflammatory cells into the affected skin with eventual loss of connective tissue of skin and mobilization of tissue-bound microelements into the vascular compartment. On the contrary, the changes in biometal levels in the sera of leprosy patients appear to be a general effect perhaps due to the release of interleukin-1, a product of inflammatory cells, causing hypercupremic, hypozincemic and hypoferremic responses in the hosts. Moreover, growth and multiplication of M. leprae, especially in polar lepromatous leprosy patients with a high bacillary load, demand essential biometals which may be mobilized into the bacterial bodies from the hosts. This perhaps results in the change in the homeostasis of the essential biometals in the hosts.