Question

How can we (our immune cells) produce so many different antibodies to responds to virtually all of the harmful antigens?

Answer 1

After early childhood, most " immune cells " are produced from the bone marrow. Some of these then undergo very significant secondary education before they are released to patrol the body. Many important immune cell types have been identified which includes lymphocyte, neutrophils, basophils monocyte etc. All of these different responses rely on the selective expression of specific families of genes.

" Immune cells" read the environment through their receptors and then modify how they use the genes encoded by their DNA. Some groups of genes are switched on, and others are switched off. This gives the different cell types a great deal of flexibility in how they handle an infection. Sometimes these gene programmes change the cytokines that cells secrete, sometimes they change the pattern of receptors on the surface and sometimes they change how resistant the cell is to infection. Information in the environment can label a specific location, keeping immune cells from moving away.

"The ability to produce billions of different antibodies in humans results from" :

• The presence of billions of complete antibody genes in B cells.
• The fact that both T cells and B cells contain antibody genes.
• The production of variable regions of light and heavy antibody genes by DNA rearrangement.
• The fact that a single antibody gene produces an antibody capable of billions of different three dimensional structures and the ability to combine with any antigen.

The " immune system creates billions of different antibodies "with a limited number of genes "by rearranging DNA segments during B cell development", prior to antigen exposure. Mutation can also increase genetic variation in antibodies. When a stem cell changes to become a B cell, DNA segments for both heavy (VDJ) and light (VJ) chains are randomly combined. Each B cell ends up with functional genes for making one light and one heavy chain coding for an antibody as a membrane-bound receptor. Antibody specificity depends on the gene fragments used. Antibodies are produced that can react with almost any chemical structure in nature, including our own proteins.