Tuberculosis vaccines currently being developed focus mainly on bolstering cell-mediated immunity (which involves white blood cells/ T cells). But those vaccines offer limited protection against Mycobacterium tuberculosis (Mtb) infections in humans. Antibody-mediated immunity has largely been neglected, mainly because Mtb located within the cell was considered beyond the reach of extracellular antibodies. In a recent study of the possible role of antibody-mediated immunity in TB prevention, Jacqueline Achkar, M.D., M.Sc., and colleagues examined the sera from 29 healthy adults before and after vaccination with BCG (the only vaccine approved for TB). They found that the vaccine elicited an IgG antibody response to arabinomannan, a polysaccharide component of Mtb’s capsule. Importantly, they showed that the higher the antibody levels, the higher the ingestion and growth inhibition of mycobacteria by an important early defense cell type called macrophage. If validated in further experimental studies, the findings could inform new approaches for TB vaccine development. The study was published April 7, 2016, in the online edition of Journal of Infectious Diseases. Dr. Achkar is associate professor of medicine and of microbiology & immunology.