Methodology for Isolation and Characterization of Granuloma Leukocytes in Mycobacterium avium Infection

Mycobacteria belonging to the Mycobacterium avium complex are opportunistic intracellular pathogens that cause disseminated infections in domestic animals and immunocompromised patients, such as those with the acquired immunodeficiency syndrome. The characteristic pathologic feature of M. avium infection is granulomatous inflammation in several tissues, including lung, liver, and spleen. We have developed the methodology for isolation of leukocytes from granulomas of M. avium-infected mice. In this review, the methodology we have utilized to isolate and characterize leukocytes from granulomas of M. avium-infected mice will be presented. The methods discussed include flow cytometric analysis of leukocytes for cell surface molecules such as activation antigens, isolation of RNA and analysis of cytokine mRNA expression by the polymerase chain reaction, and determination of granuloma leukocyte cytokine production using the enzyme-linked immunosorbent assay. In addition, the potential usefulness of M. avium infection as a model for the study of activated T lymphocytes is discussed.