OSMT (Ontario Society of Medical Technologists) Practice Exam

Which antibody is primarily responsible for detecting foreign antigens in the respiratory tract?

1. a. IgG

2. b. IgM

3. c. IgA

4. d. IgE

The correct answer is: c. IgA

The correct answer is based on the role of immunoglobulin A (IgA) in the immune response, particularly in the respiratory tract. IgA is the primary antibody found in mucosal areas, which include the respiratory tract, gastrointestinal tract, and urogenital tract. Its main function is to prevent colonization by pathogens and protect mucosal surfaces from infections. In the respiratory tract, IgA plays a crucial role by binding to foreign antigens such as bacteria and viruses. This binding prevents these pathogens from adhering to epithelial cells, thus hindering their ability to establish an infection. Additionally, IgA can neutralize toxins and viruses, further contributing to the immune defense. While other immunoglobulins like IgG and IgM also contribute to the immune response, they are not primarily associated with mucosal immunity. IgG is the most abundant antibody in the bloodstream and provides systemic immunity, while IgM is the first antibody produced in response to an infection but does not have a strong presence in mucosal areas. IgE is primarily involved in allergic reactions and responses to parasitic infections rather than the direct detection of foreign antigens in the respiratory tract. Therefore, due to its specific presence and function in mucosal surfaces, including the respiratory system