How TB Evades Immune System Detection.

• Position: Tuberculosis - Brief Article

Tuberculosis is one of the deadliest scourges of humans, infecting about one-third of the world's population, or 2,000,000,000 people, killing an estimated 8,000,000 individuals annually. While a vaccine exists for children, an effective one for adults remains elusive.

Tuberculosis is caused by Mycobacterium tuberculosis, a bacterium that can be transmitted through the air. If it is left untreated, TB can cause the development of cavities in the lungs and other tissues, leading to a variety of symptoms, including severe cough (at times with blood), fever, and weight loss, and might become life-threatening. Growth of the bacteria in the lungs of infected persons is controlled in many cases, but not eradicated, by the immune system. When immunity fails because of malnutrition, aging, or HIV infection, the bacteria grow, causing active TB of the lung.

When an infection invades the body, the immune system is called upon to control and stop it. Important soldiers in the war against infection are scavenger cells called macrophages, which chew up invading bacteria and deliver pieces of them to CD4 T white blood cells. Macrophages have a specialized set...