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Immunology is not my best subject, anyone care to lay out the basic principles of the different immune cells?
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Originally posted by Monique
Could you explain to me how the immune cells know not to attack the organisms own cells? What I remember is that all kinds of antigen binding domains are made, after which the ones that recognize 'self' are iliminated?
Originally posted by Monique
What exactly is the role of MHC in immunity?
I appreciate that :)Originally posted by iansmith
That is the principle. For T-cell there is two selection. positive selection is in the thymus and only the T-cell that recognize the self-MHC molecules are keep (self-MHC-restricted T-cell). Negative selection eliminates T-cells that recognize self-MHC too strongly (Self tolerant T-cell). Our prof use to call this the thymus school.
Originally posted by Monique
T-cells that recognize the self-MHC are kept. What does that mean? What is this recognition
Originally posted by Monique
what then keeps them from tagging 'self' cells?
Originally posted by iansmith
Negative selection eliminates T-cells that recognize self-MHC too strongly (Self tolerant T-cell).
Only a cell that has self MHC is able to present antigens to the T-cell, but who says the antigens are not self?? Why can't foreign MHCs present antigens? Why not?Originally posted by iansmith
MHC is required for presenting Antigen to T-cell. T-cell only recognize self-MHC. Also for graft rejection, T-cell will recognize the MHC on the graft material as foreign i.e. as non self-MHC.
Originally posted by Monique
Only a cell that has self MHC is able to present antigens to the T-cell, but who says the antigens are not self??
Originally posted by Monique
Why can't foreign MHCs present antigens? Why not?
Originally posted by Monique
I am not quite sure about the negative selection either.. how does the cell in the thymus know it recognizes the self MHC too strongly?
I really don't see why immunity has selected that T-cells only react to antigens presented by innate cells.. and why these cells don't present antigens that are infact innate.. probably because the antigen binding structures are in fact the things which are selected for in thymus, that would make sense! ha!Originally posted by iansmith
Non-self MHC can present antigen but T-cell will not recognize the MHC complex because it has been selected to only recognize self MHC. There actually an experiment that demontrated that. I'll to go through my notes.
Originally posted by Monique
I really don't see why immunity has selected that T-cells only react to antigens presented by innate cells.. and why these cells don't present antigens that are infact innate..
Originally posted by Monique
probably because the antigen binding structures are in fact the things which are selected for in thymus, that would make sense! ha!
Originally posted by Monique
The answer still then needs to be answered HOW this selection of MHC AND antigen binding domains takes place in the thymus..
Originally posted by Monique
I mean, how many proteins are there in the human body? All are potential antigens..
Originally posted by iansmith
If the binding is unspecific (i.e. does not recognize self) then the cell go into apoptosis. Imagine if the imunne system did not recognize self then everybody would have some auto-immune disease because the immune system could not make the difference between invader and self. During negative selection, if the binding is too strong (too much specific) it probably illicit some reaction and then the cell goes into apoptosis.
Does that really happen like that? I know that cell death not by apoptosis can give a nasty inflammation on site..Originally posted by None
but what's to stop one of those fragments from being picked up by a circulating APC? (antigen presenting cell)
brainyman89 said:What i meant to ask is if T cells are normally restricted to recognizing foreign peptides displayed by self-MHC molecules, why should these T cells recognize foreign MHC?
Monique said:Does that really happen like that? I know that cell death not by apoptosis can give a nasty inflammation on site..
The immune system is composed of several types of cells, including white blood cells such as B cells, T cells, natural killer cells, and phagocytes.
B cells are responsible for producing antibodies, which are proteins that bind to and neutralize foreign invaders in the body.
T cells are responsible for cell-mediated immunity, meaning they directly attack and destroy infected or abnormal cells in the body.
Natural killer cells are a type of white blood cell that can directly kill infected or cancerous cells in the body without prior exposure or activation.
Phagocytes, also known as scavenger cells, engulf and digest foreign particles or pathogens in the body, helping to prevent and fight infections.