Natural Killer Cells

The Innate Immune System - Module 5

There are four main groups of non-cytotoxic ILCs.

**False** - There are only three main groups of non-cytotoxic ILCs: ILC1, ILC 2 and ILC3.

Descriptions of ILC3

1. Support lymphoid tissue development
2. Support anti-bacterial defense via IFNg
3. Help mucosal response

What is the function of perforin in immune defense?

Target Cell Lysis

Natural killer cells are activated when they bind to a cell without:

MHC class I

At distinct tissue sites e.g. lung, thymus and liver, NK cells have identical phenotypic features and functions.

False - NK cells have different phenotypic features and functions.

How do NK cells destroy their target?

They release lytic granules and use death receptors

NK cells are defined by differential expression of CD16 and NKG2D.

True

Binding of an activating receptor in the absence of inhibitory signals leads to NK cell _______.

Activation

An activated NK cell can destroy a cell expressing:

Absent MHC class I and an NK cell ligand

What are the NK activating receptors?

1. KIR
2. CD16
3. NKG2D

What is the percentage of NK cells in peripheral-blood lymphocytes in humans?

Approx. 10-15%

ILC1 predominantly express IL5 and IL13

False - In fact, ILC1 predominantly express IFNy