Few questions about immunology

[sameeralord]

1. Why can't antibodies enter virus infected cells. Why can't virus infected cells make their membrane permeable for antibodies.

2. Why doesn't the body create antibodies against self. What is the mechanism behind the body knowing which cells are self and non self.

3.How do memory cells increase the response second time. Do the antigens get bind to memory cells quicker and then the process activates faster.

4. How are white blood cells produced in lymph?

Thank you!!

[icedoverfire]

In response to question #2, a (very) simplistic explanation:

Self and non-self are both antigen mediated... it's just that there are self antigens and non-self antigens. So I think you could say the body does create antibodies against itself, but a self antigen leads to a "null" response whereas a non-self antigen leads to an immune response.

I think it may have to do with MHC proteins.

Hope this helps,

-ice

[sameeralord]

Thanks for the response. Yeah I'm thinking of getting into a uni course related to science. Not sure yet. :smile:

[Monique]

These questions are all answered in introductory immunobiology books, the immune system is really complex with many different cell types and responses associated with it. It would take me too much time to go into great detail, but maybe I can give you some answers that will put you in the right direction of thinking.

1. Why can't antibodies enter virus infected cells. Why can't virus infected cells make their membrane permeable for antibodies. Only soluble or small molecules are membrane permeable.

2. Why doesn't the body create antibodies against self. What is the mechanism behind the body knowing which cells are self and non self. When immune cells are made in the thymus during embryogenesis they reshuffle their genes that allow them to recognize antigens, these native cells will recognize both self and non-self. A quality-control is then undertaken to deplete all the cells that recognize the self-antigens plus self-MHC. Only cells that recognize only the MHC will survive, these can then bind foreign antigens that are displayed by the MHC on immune cells.

3.How do memory cells increase the response second time. Do the antigens get bind to memory cells quicker and then the process activates faster. The memory cells are made after a successful immune response, they have a long life-time and will circulate in the blood until they are challenged again. This response of re-activating the existing memory cells takes less time than when the immune system needs to start an immune response from scratch.

4. How are white blood cells produced in lymph? White blood cells are produced in the bone marrow, the lymph is where they can mature or accumulate.

[hypatia]

I highly recommend taking several classes involving human biology. Its really good to know how our body works, and its really interesting.

[AyazM]

1. Antibodies do not enter cells. Remember that an organism that resides INSIDE the cell, for instance Mycobacterium Tuberculosis or Hepatitis B virus, requires Cell-mediate killing. That is to say, cells would kill, not antibodies.

2. Self vs non-self is already explained by monique. The body DOES make antibodies against itself in special circumstances which you may not need to know. But just for example, rheumatoid arthritis is a case where body makes antibodies against its own antibodies! Interesting? :)

3. Just to add to monique's response, everything is ready in anticipation for a second attack. The cells go back to their original place where they first encountered the offense, fully armed with artillery. In case of B cells, the genetic re-arrangement is already there for the specific antibody and there are many clones. Because of those clones, the second response is quick and sustained.

4. Bone Marrow makes all blood cells. White cells rest in lymph nodes because they have a really good chance of encountering some bacteria. Remember if for instance you have a scratch on your hand and bacterium enters, it is drained by the lymph to the nearest lymph node.