Immunology Flashcards

Which cells are considered the 'professional' antigen-presenting cells (APCs) most efficient at activating naive T cells?

Answer: Dendritic cells

Dendritic cells are the most potent professional APCs because they express high levels of MHC molecules and co-stimulatory signals needed to prime naive T cells.

What is clonal deletion in the context of T cell development?

Answer: Elimination of self-reactive T cells in the thymus

Clonal deletion is the process in the thymus where T cells with high affinity for self-antigens undergo apoptosis during negative selection.

Which antibody isotype is most abundant in mucosal secretions such as saliva and breast milk?

Answer: IgA

Secretory IgA (sIgA) is the predominant antibody in mucosal secretions and provides first-line defense at mucosal surfaces.

What does the term 'somatic hypermutation' refer to in B cell biology?

Answer: Targeted mutations in immunoglobulin variable regions to increase antibody affinity

Somatic hypermutation introduces point mutations in the variable regions of immunoglobulin genes, allowing for the generation of B cell clones with higher antigen affinity.

Which pattern recognition receptor is responsible for detecting lipopolysaccharide (LPS) from gram-negative bacteria?

Answer: TLR4

TLR4 (Toll-like receptor 4) recognizes LPS from gram-negative bacterial cell walls, triggering innate immune responses.

What is the mechanism of action of cytotoxic T lymphocytes (CTLs) when killing infected cells?

Answer: Releasing perforin and granzymes to induce apoptosis

CTLs kill infected cells by releasing perforin (which forms pores in the target cell membrane) and granzymes (serine proteases that trigger apoptosis).

In which disease would you expect to find elevated IgE levels and eosinophilia?

Answer: Allergic asthma

Allergic asthma is characterized by Th2-mediated responses, leading to elevated IgE production and eosinophil recruitment to airways.