Preksha Dhyana Human Body Part 2

Author(s): Jethalal S Zaveri
Publisher: Jain Vishva Bharati

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Antibodies
It is known for a long time that the body is capable of producing proteins called antibodies, which react with invading microbes, inactivating or killing them. A variety of antibodies are found in the circulating blood even in a healthy person. They are all proteins called immunoglobulins. Five groups have been found, differing in chemical properties and biological functions. Some provide most of the specific immunity against microbes. Some are involved in allergic reactions. The total picture of antibodyproduction and the action of the immunity-system as a whole is, however, very complex indeed.
B and T Cells and Antibodies
There are two major classes of lymphocytes. They are called B-Cells and T-Cells. Percusors of both are originally formed in the bone-marrow. Some of these then migrate to the thymus gland where they are transformed into T-lymphocytes (T for thymus). The other percusors take a different route. In birds, the transformation into B-Cells occurs in a gastrointestinal structure called bursa (B for bursa). Human beings do not have a bursa and although it is believed that a comparable site exists, it is not yet known where or what it is.
There are structural as well as functional differences betwen the two types of lymphocytes. T-Cells somehow help B-Cells to become active antibody producers. T-Cells can also suppress B-cell activity. This role is important in the recognition of "self" cells and chemicals that keep the an. tibody system from destroying our own body tissues. T-Cells can also act directly as killers. Another important function of the T-Cells is to conduct an immune surveillance. If a body-cell becomes malignant, patrolling T-Cells which perceive it as antigen (i.e. foreign), are sensitized and attack it and other similar cells. It is believd that body-cells become malignant at the rate of one everyday, but are promptly
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