Читать книгу The Slim Book of Health Pearls: Challenging Diagnoses - Sheldon Cohen - Страница 7

Immunity is the body’s ability to defend against specific invaders. In addition to the property of specificity, the immune process also includes the ability of the body to prepare a future defense against the invader; in other words—memory.

When T and B cells are finally formed (T in the thymus…B in the bone marrow), they are said to be immunocompetent. This means that when the T cells leave the thymus and the B cells leave the bone marrow they have on their surface some distinctive proteins or antigen receptors labeled CD4 or CD8. These antigen receptors are programmed to attack specific antigens. Those T cells that have the CD4 protein are helper T cells, and those T cells that have the CD8 protein are killer T cells.

Before getting specific about killer T cells, it is important to know that there are two types of immunity:

1.The first is cell-mediated cell immune response (CMI) where CD8 cells become killer cells and attack an invading antigen. This also goes by the name of cellular immunity.

2.The second type of immunity is antibody-mediated humeral immune response (AMI) where B cells change into plasma cells that manufacture and secrete specific proteins called antibodies or immunoglobulins that bind to a specific antigen. This goes by the name of humeral immunity (humeral means body fluids).

CD4 cells become helper cells, and as the name implies they “help” the CD8 cell become killer cells, and help the B cell change into plasma cells, little factories that produce specific antibodies by the millions.

Cellular immunity is effective against pathogens that enter cells (intracellular pathogens) such as bacteria, fungi, viruses, cancer cells, and foreign transplants. An attack on an intracellular pathogen is an attack by cells on cells.

Humeral immunity (antibodies) attack antigens dissolved in body fluids, and extra cellular pathogens (mainly bacteria) that multiply outside of cells.

As you can see, each of these different forms of immunity has their preferred battlefield.

Here are some important points to remember:

•An immune system stockpiles an incredibly large arsenal of cells.

•Nonspecific immunity SEE APPENDIX 1

•Cells programmed to attack specific targets (T and B lymphocytes…specific immunity)

•Immune cell cooperation with each other either by direct physical contact or through chemical message

•Millions of invaders attack the body

There are one trillion (1,000,000,000,000), give or take a few billion (few,000,000,000) cells. However, even with this number the body does not store an equal match for each of the millions of predators. Rather, the immune system will store a small amount of lymphocytes of each specific type, and when these cells identify the specific invader’s chemical message they have the ability to multiply rapidly to form a defensive army whose adage is “the best defense is a strong offense.”