Host Barriers to Infection

What are the main aims of immunity?

To protect against pathogens by distinguishing self from non-self and killing or disabling pathogens.

What is the first line of defense in host defense mechanisms?

Physical barriers such as skin, tight junctions, and the blood-brain barrier.

What characterizes innate immunity?

A rapid, non-specific defense mechanism that lacks true adaptive memory.

What cells are primarily involved in adaptive immunity?

B cells and T cells and antibodies

What are antimicrobial peptides (AMPs)?

Ancient immune defense mechanisms present in all organisms, with broad-spectrum antimicrobial activity.

What is the function of the complement system?

A group of plasma proteins involved in opsonization, inflammation, and pathogen killing.

What does C3 convertase do?

C3 convertase cleaves C3 into C3a and C3b, with C3a promoting inflammation and C3b promoting phagocytosis.

What are some examples of phagocytic cells?

Macrophages, dendritic cells, and neutrophils.

How does Cryptococcus neoformans evade the immune response?

By hiding its epitopes with a capsule.

What is antigenic variation as it relates to influenza?

Small mutations lead to new seasonal strains through antigenic drift, while major genome reassortment can produce entirely new variants through antigenic shift.