Immunity question

[NubianPrincess]

I cant see much differece between humoral immunity and cell-mediated immunity. They seem like the same mechanism but with different cell names...cells that destroy antigen and cells that remember antigen. Does only humoral immunity use antibodies?

Ugh I am confused they look the same to me.

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[Nuel]

Humoral immunity involves antibodies from B-cells--the so-called immunoglobulin proteins. Cell-mediated immunity (also called T-cell-mediated immunity) primarily involves T-cells (Th, Tc, Ts--helper T cell, cytotoxic and suppressor respectively).

However, both mechanisms are interrelated in the immune response as in one stimulates the proliferation of the other, I mean Tc-cells can stimulate proliferation of the B-cells in the presence of antigen-presenting cells (APCs). It is this nice detailed cycle that I don't think is required for the MCAT. I vaguely remember the whole detail myself.

 

[NubianPrincess]

Thanks for your response, Nuel

 

[LUBDUBB]

I'll give it a shot


Humoral immunity -

production of antibodies in response to an antigen - Mediated by B-cells ( B- lymphocytes).

Upon entering the body, an antigen is recognized by the B-cells. The B-cells enter into secondary lyphoid tissue (e.g. lymph nodes) and differentiate into plasma cells and memory cells. The plasma cells produce the antibodies. The memory cells serve to facillate the immune response upon a second subsequent exposure to the antigen.

Cell Mediated Immunity - mediated by T-cells

T- cells differentiate into

Cytotoxic T - cells to destroy the body's cells that have become infected with the antigen.

Helper T cells - which release cytokines to stimulate the proliferation of b-cells and also cytotoxic t-cells.

Suppressor T cells - which serve to suppress the immume response after the antigen has been removed.


It is important to remember that B-cells (humoral immunity) release antibodies that directly attack the antigen. But in cell-mediated immunity, the body's cells already infected are attacked. Depending on the pathogen, one is often more important that the other.

 

[NubianPrincess]

Originally posted by LUBDUBB
It is important to remember that B-cells (humoral immunity) release antibodies that directly attack the antigen. But in cell-mediated immunity, the body's cells already infected are attacked. Depending on the pathogen, one is often more important that the other.

Interesting. Lubdubb, your synopsis made alot of sense. Thanks

 

[pathdr2b]

An important distinction between B and T lymphocytes is that B-Lymphocytes form plasma cells which secrete antibodies. T-Cells are also thymus derived.

I believe this information is somewhat helpful for MCAT Test 5R, Passage 1.

 

[Persistence101]

Also remember that antibodies bind to the antigen in order to either neutralize it or aid in the process of phagocytosis of antigen. Just think of the B cells as shooting antibody missiles which attaches to the antigen surfaces. this will neutralize the antigen so it can't attach to other cells in our body and the macrophages will be better able to detect and engulf the antigen-antibody complex. just remember that antibodies themselves can't destroy the antigen, they have to attach to the antigen and the whole complex will be engulfed and digested by macrophages. whereas in t-cells, onces it's activated by antigen presenting cells, it releases chemicals that will destroy the infected cell.

 

[dfleis]

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[CoverMe]

Immunity... for some reason i was thinking of a Survivor-ish Immunity Challenge to get out of the MCAT. I think those ******* on TV would have to sit back and learn something about competitiveness if AAMC offered THAT kind of immunity!