DIAL 2. Basic Immunology - Functions and Disorders of the Immune System

Question 1

Explain the concept and function of pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs) and pattern recognition receptors (PRRs) in innate immunity

Answer 1

PAMPs are molecular markers found in microbes that indicate to the innate immune system that the cell is a pathogen. DAMPs are molecular markers that are released by human cells to indicate necrotic cells. These molecular markers are not highly specific and are structures that are shared by various class of microbes that are not found on normal host cells. The molecular markers are recognized by PRRs.

Question 2

Describe the general features, cellular localization and functions of Toll-like receptors (TLRs).

Answer 2

Different TLR’s recognize difference parts of microbes. (bacterial lipoglycans, viral nucleic acids). Some TLR’s are present on the cell surface to recognizes extracellular microbes. Some TLR’s are in endosomes in which microbes are phagocytosed. After TLR binding, transcription factors are activated to promote expression of cytokines, endothelial adhesion molecules, etc.

Question 3

Describe the general features and functions of NOD-like receptors (NLRs), the inflammasome and RIG-like receptors (RLRs).

Answer 3

NLR - a large family of cytosolic receptors to that sense DAMPs and PAMPs in the cytoplasm. When NLR’s are activated, IL-1B is activated (which induces acute inflammation). The Inflammasome refers to the cytosolic complex of NLRP-3 (receptor), an adaptor, and caspase.
RLR - cytoplasmic receptors that recognizes viral RNA.

Question 4

Compare and contrast the major receptor for innate and adaptive immunity in regard to specificity, expression and self/nonself discrimination.

Answer 4

Innate - PRR (TLRs, NLRs, RLRs), specific for PAMPs and DAMPs, are coded for in the germline, and do not recognize healthy host cells.
Adaptive - Highly specific(greatly diverse) receptors are coded for by somatic recombination of gene segments. Self-reactive lymphocytes are selected against during lymphocyte maturation.