Immune Response to Mycobacterium Tuberculosis Infection

Study Summary

This study will examine how the immune system responds to infection with Mycobacterium tuberculosis bacteria (bacteria that cause tuberculosis) in order to better understand how the germ produces infection and how the immune response might work to control the infection. Only about one in 10 people infected by M. tuberculosis become sick, sometimes years or even decades after exposure. It is not known why some people become sick and most do not, but the immune system of people who never develop disease may be better able to control the bacteria. This study will evaluate the latent form of M. tuberculosis infection to further the understanding of the immune mechanisms - particularly the role of certain white blood cells - involved in the disease process. Healthy volunteers 18 years of age and older may be eligible for this study. Candidates are screened with a medical history, family history of medical conditions, sexual history, history of drug use, physical examination and blood tests, including a test for HIV. People in Mali, West Africa, and in local health clinics in the United States may participate. At the start of the study, participants have blood tests and a tuberculin skin test (PPD test), which indicates whether a person has been exposed to tuberculosis bacteria. For the PPD, a tiny amount of liquid containing dead tuberculosis antigen is put under the skin of the forearm with a needle. The antigen cannot cause infection or disease. After 3 days, participants have another blood test and the site of the tuberculin test is examined for swelling that would indicate a positive result. Participants with a positive PPD have a chest x-ray to check for tuberculosis disease. Those whose x-ray is also positive are withdrawn from the study and referred to their doctor for evaluation and treatment. Those whose x-ray is negative return to the clinic within 3 weeks of the tuberculin test to give another blood sample. Participants whose PPD is negative have a second

Conditions Studied

Study Locations (2)