NK Cells

Question.

210. All of the following statements about NK cells are true. except:

1. They are derived from large granular cells.

2. They comprise about 5% of human peripheral lymphoid cells.

3. They are MHC restricted cytotoxic cells

4. They express lgG Fc receptors.

Answer

3. They are MHC restricted cytotoxic cells

Reference

Nelson 15^th Edition Chapter 116

Ananthanarayanan 5^th Edition Page 116

Harrison 15^th Edition Page 1810

Quality

Reader

Status

Repeat from All India

QTDF

All books

Discussion

Natural Killer Cells

· These are large, granular lymphocytes, not classical T or B cells

· They belong to the group of Null Cells

· They account for 5 to 10 % of Lymphocytes

· Lyse cultured tumour cells and virus-infected cells very efficiently in vitro.

· Interferon is a potent activator of natural killer cells.

· IL 2 activates them to LAK cells

· They express

o CD 16 –FcR for IgG

o CD 56 – Mediates NK Homotypic Adhesion

Explanation

1. They are derived from large granular cells.

2. They comprise about 5% of human peripheral lymphoid cells.

3. They are defined by their functional capacity to mediate non-MHC-restricted cytotoxicity.are not MHC restricted cytotoxic cells

4. They express lgG Fc receptors.

Comments

NK-cell activity has been found in human fetal liver cells at 8{endash}–11 wk of gestation. NK lymphocytes are also derived from bone marrow precursors. Thymic processing is not necessary for NK-cell development, although NK cells have been found in the thymus.

Tips

The names and other details of various Cluster of Differentiation are to be studied from Nelson, Harrison and Robbins. Table 305-1 from Harrison is to be read (that’s easy J!!) and to be remembered (how L??)