Question

Some bacteria produce multiple toxins that interfere with the host’s immune response. For example, one bacterial toxin is a protease that cleaves the proteins that form tight junctions between skin cells. The result is severe, widespread blistering (patches of skin sort of peel away from the body). The same bacteria also synthesize another protease that cleaves the hinge region of immunoglobulins. Describe, in specific terms, how this activity affects antibody function.

Answer 1

Antibodies represent a primary line of defence system against attacking pathogens. The effectiveness of any antibody depends upon its structural integrity. Antibodies bind to antigens with the help of Fab region, while the Fc regions interact with the Fc receptors present on white blood cells (namely natural killer cells, monocytes, macrophages, neutrophils, and B and T lymphocytes)

When bacterial species secrete proteases that can destroy this integrity, they essentially cleave proline-serine or proline-threonine peptide bonds in the hinge region of antibodies. This means that the Fab region is separated from the Fc region, which reduces the effectiveness of the antibody molecule. It fails to interact with further bacterial cells, and as a result, cannot mount an effective immune response against the pathogens.