Question

What is the main function of the Nk cells in the organism defense? and how it work?

Answer 1

I'm a bit shaky on the immune system, but vertebrates have two divisions: your innate (for example, skin barriers and mucus) system and your adaptive system (this is what gives you immunity).

In both systems, you have cells that specifically seek out and destroy infected cells. In your innate system, these are called the Natural Killer cells; the role is played by Cytotoxic T Cells in the adaptive system.

After recognizing a diseased cell, the NK cell works by inducing apoptosis. It creates a hole in the membrane of said diseased cell the protein perforin, and then releases granzymes, which are chemical messengers, into the cell. Granzymes activate caspases - these proteins run around chopping up other caspases and parts of the cell and basically cause it to self-destruct, in a controlled manner.

Answer 2

yeah, It´s correct, but I was reading about it, and I discovered that, the NK cells only works in the cells infected by virus and in tumor cells. it's correct, right?

Answer 3

Hmm I'm not certain if NK cells /only/ target those types of cells, but yes - they are definitely especially suited for destroying those virally infected and tumor cells.

Answer 4

To add on which type of cells they target, i have to bring up a cell component all cellular membrane in the body has (except erythrocytes thats why we can do blood transfusion without immunosuppresants). Anyway, the complex is MHC (Major histocompatibility complex). NK cells patrol your body and if they find any cell without this complex they will induce apotosis (Kma230 explained this better), In cancergenic cells this complex usually is either abscent or different then your other bodily cells, same thing applies to most virusinfected cells. NK cells do fight other pathogens aswell. They patrol the body without any immunological response.

Also @kma230: I believe what the immune system is split into 3 groups
First line of defence - Skin, mucosa, cilia, HCL- in the stomach
2n'd line of defence - Innate immune system: Eosinophil, Basophil, Neutrophils, Monocytes(Macrophages) etc..
3n'd line of defence - Adapative immune system: Lymfocytes, T-lymfocytes, B-plasma cells, CD4, CD8. etc

Answer 5

Nice explanation @exuras and thanks for the correction!

Answer 6

@exuras but the Skin, mucosa, cilia, HCL- in the stomach belongs to the innate system

Answer 7

@MarcoClementino Well what i've been taught is that there are 3 line of defence
1'st: Anatomical barrier
2nd: Innate immunity system
3rd: Adaptive immunity system

This seems to be a schematic of the innate immune system, from what it seems to represent is that when a pathogen has bypassed the anatomical barrier therefore entered 2nd: Innate immunity system
http://upload.wikimedia.org/wikipedia/commons/a/a9/Innate_immune_system.png

Answer 8

ahh, got it ^^ sorry for my mistake

Answer 9

thank you guys ^^