Killer T and Cancerous cells.

[jayson]

Killer T Cells are responsible for killing the cancerious cells and foreign microbes or cells. The K.T cells are able to detect a foreign cell by its antigen.

My question is that, since the canerous cell is produced in the body, it would have the same antigens as the rest of the cells in the body. Antigens that are comptiable and acceptable to the body. So how would the Killer T Cells be able to know that this certain (cancerious) cell is harmful ?

[sdekivit]

the killer T-cells don't recognize tumor cells, the natural killer cells recognize them, because they don't express MHC-I om the surface anymore.

Natural killer cells are NOT the same as killer T-cells.

[victor]

simply said that cancerous cells doesn't have the self antigen anymore...so Tc cells (Tc = T-cytotoxic) will get rid of it as soon as possible...and yes, NK cells are different from Tc cells ecause NK cells do not have CD3 receptors like TC cells do..

[Poison]

Yes, cancer cells have different antigens, that's why they can be detected.

[jayson]

Yes, cancer cells have different antigens, that's why they can be detected.

So even though the cancer cells are produced in the body, they have different antigen ?

[victor]

Yup, und immunologically, we we call it as non-self. CD4+ and CD8+ antigen receptors know the difference between self and non-self.

[Poison]

Yes, cancer cells have different antigens, that's why they can be detected.

So even though the cancer cells are produced in the body, they have different antigen ?

Yes. they have different antigen. They are different, can not stop dividing, have different antigens etc...

[Ultrashogun]

Yes, cancer cells have different antigens, that's why they can be detected.

May seem like a stupid question for you guys, but if they can be detected why cant they be killed?

[sdekivit]

what can't be killed ? if a cytotoxic T-cell recognizes it, the cancercell will die, but that doesn't necessarily mean the tumor itself will die.

[Poison]

May seem like a stupid question for you guys, but if they can be detected why cant they be killed?

In your body, everyday about 20 cancer cells are produced, they are detected and killed. But some are harder to be detected, plus they reproduce so fast that you can not stop. The malign tumors rise in those situations.

[Dr.Stein]

_at_ Vic:
I think cancer cells is still have self antigen in addition to new ones (nonself) resulted from mutation. They present processed antigen as peptide, both self peptide and nonself peptide with MHC-I, in which NK will recognize it as normal cell or cancer cell.

@sdekivit:
I read that there are two theories on how NK recognizing cells as an abnormal one, including cancer cell. First, they present less MHC-I than the normal cells. Second, they find a nonself peptide presented by MHC-I. I have a nice figure for this, unfortunately I need to scan it. Or maybe you already have it? It is from Janeway's Immunobiology book. I remember the figure is on the left upper side

[sdekivit]

Janeway is a great book