QCM : Immunology Fundamentals — 9 questions

Explication

Antigens are substances that induce an immune response and are recognized by specific immune determinants (epitopes). They are usually foreign, high molecular weight molecules like proteins or polysaccharides, which trigger the immune system to produce antibodies or activate immune cells.

Explication

IgA is the main immunoglobulin responsible for mucosal immunity and is found in secretions like saliva and breast milk, helping protect mucosal surfaces from pathogens.

Explication

IgA is the immunoglobulin class predominantly found in mucosal secretions such as saliva, tears, and breast milk. It plays a crucial role in mucosal immunity by preventing microbial attachment and invasion at mucosal surfaces, thereby protecting the host from infections.

Explication

Kunkel and Edelman described immunoglobulins as glycoproteins with five classes in 1959, establishing a foundational understanding of antibody diversity.

Explication

The zone of equivalence is the optimal ratio of antigen to antibody in a precipitation reaction, where they are present in just the right proportions to form visible immune complexes or precipitates. This zone is essential for the detection and measurement of specific antigens or antibodies in laboratory tests.

Explication

The prozone phenomenon occurs when excess antibodies prevent lattice formation, leading to false negatives in serological tests.

Explication

While IgG can activate complement and cross the placenta, it does not primarily neutralize toxins; IgG neutralizes toxins via other mechanisms.

Explication

Cytotoxic T cells (CD8) recognize processed antigens presented by infected cells and induce apoptosis, eliminating infected cells.

Explication

IgE mediates allergic reactions by binding to mast cells and basophils, leading to histamine release upon allergen exposure.