B Lymphocytes Action

Hi,

I notice you get up slightly earlier than the general student population (esp on Sunday!) Well done!

The B cell response leading to humoral immunity, is part [the other being cellular immunity mediated by T lymphocytes] of the adaptive immunity process (kind of in response to infection i.e. occurring after an insult to the body) [the other arm of the immune system being the innate immunity system (active all the time kind of preventative [before])].

When a B cell is stimulated to respond by the recognition of an antigen (a part [usually a protein] of a bacterium, virus, fungus, etc, that is seen as "foreign" (although can in certain situations be a part of the person's own cells = self item that is erroneously looked at as "foreign" leading to auto-immune disease e.g. rheumatic fever [now v rare] or myasthenia gravis, where the patients own antibodies attack his/her own cells, but google the word "hapten"]).

The activated B cell then "matures" into a plasma cell (that is rich in RER and has a well-developed Golgi - WHY? OK work it out ----------------------------------------------------------------- yes well done (it is going to synthesize protein - in this case an antibody [the plasma cells divide very rapidly to produce millions of identical plasma cells which then produce millions of molecules of identical [monoclonal] antibody that IS SPECIFIC TO THE ORIGINAL ANTIGEN that was identified. These antibodies (there are five main categories of them, but for A level purposes, just remember that one of them is a small molecule so it can cross the placenta in a gravid woman and confer some immunity to the baby [which lasts for about 6 months after birth]).

These antibodies then attack the foreign material [more often bacteria, since the T cells phagocytose viruses as a general rule [as viruses are smaller and easier to "swallow" - hence severe viral infections occur in AIDs, where the HIV virus attacks T cells]] resulting in aggregation or precipitation of the pathogen and resulting destruction of the pathogen [Greek pathos = disease; gen = generate as in Genesis of Bible hence pathogen = disease-causing entity] OR the antibody may make a pathogen easier for a T lymphocyte to phagocytose = opsonisation.

Certain B cells are saved long term (also T cells similarly since T and B lymphocytes work "in tandem") to provide memory of the original offender [antigen] so that a very quick and voluminous response occurs if the same antigen enters the system in future [remember this as being analogous to the police keeping watch and being ready to attack/arrest a terrorist if he/she tries to hurt innocent citizens again in future] [this is the scientific basis of vaccination invented by Edward Jenner in cows who developed cowpox [similar to smallpox in humans]].

I hope this helps!

M (specialist biology tutor)