Medical News Observer

A study led by investigators from the Ragon Institute of MGH, MIT, and Harvard finds evidence that antibody protection may help control infection with the bacteria that causes tuberculosis. In their study, which received online publication in Cell, the research team described consistent differences in the structure and function of TB-specific antibodies targeting the TB bacteria. They noted these differences between individuals with active TB disease, which produces symptoms and can be transmitted, and those with latent TB, which neither produces symptoms nor can be transmitted.

“A more effective vaccine against TB could substantially contribute towards that goal, impacting the nearly one in three people worldwide who are infected and addressing the leading killer of individuals infected with HIV.” The only currently available preventive against infection with the TB bacteria – the BCG vaccine – has been available since the 1920s. BCG vaccine effectiveness against pulmonary TB, the most common form of the disease, has always been uncertain.

Study

Previous investigations into a possible role for antibodies in the immune response to TB have had conflicting results, but the research team used a novel approach. In addition to binding to their target pathogens and marking them for destruction by the immune system, antibodies also directly stimulate pathogen-killing cells of the innate immune system by binding to a cell-surface protein called the Fc receptor.

TB-Specific Antibodies

The Ragon team profiled TB-specific antibodies from 22 individuals who were from South Africa with latent TB and 20 with active TB for 70 different features associated with Fc-mediated antibody function. They first identified nine characteristics that differentiated between antibodies of the two groups of participants. Further analysis identified the biomarker that best distinguished between them. Researchers found distinct differences in glycosylation patterns between latent TB antibodies from active TB antibodies.

To confirm these results, the team conducted a similar analysis of antibodies from 20 individuals from Texas and Mexico and had the same results. Further experiments revealed that the application of latent TB antibodies to TB-infected human macrophages increased the activation of several antimicrobial processes and reduced the survival of the TB bacteria.

Reference

• Press release: Antibody function may help keep tuberculosis infection under control
• Lu, Lenette L., Amy W. Chung, Tracy R. Rosebrock, Musie Ghebremichael, Wen Han Yu, Patricia S. Grace, Matthew K. Schoen, et al. 2016. “A Functional Role for Antibodies in Tuberculosis.” Cell 167 (2): 433-443.e14. https://doi.org/10.1016/j.cell.2016.08.072.