What are the Characteristics of Antibodies?
Answers
Antibodies show the following characteristics and perform different functions.
(i) IgA:
It is the second most abundant class, constituting about 10 to 15 per cent of antibodies of serum. It is mainly found in sweat, tears, saliva, mucus, colostrum (first milk secreted by a mother) and gastrointestinal secretions.
(ii) IgD:
It is mainly found on the surfaces of В cells as antigen receptors, where it activates В cells for antigen recognition. It is about 0.2% of all antibodies in the blood.
(iii) IgE:
It exhibits unique properties such as heat lability (inactivated at 56°C in one hour). IgE mediates type I hypersensitivity (anaphylaxis). Prausnitz and Kustner in 1921 demonstrated transmission of IgE-mediated type I hypersensitivity. It is called Prausnitz-Kustner (PK) reaction. Thus IgE acts as mediator in allergic response.
(iv) IgG:
This is the most abundant class of Ig in the body constituting approximately 80% of the total Igs. It is found in the blood, lymph and intestine. It protects against bacteria and viruses by enhancing phagocytosis, neutralizing toxins and complement activation. It is the only class of antibody to cross the placenta from mother to foetus thereby conferring considerable immune protection in new-borns.
(v) IgM:
cannot cross the placental barrier. IgM is 500-1000 times more effective than IgG in opsonisation (to be described ahead), in bacterial action and in bacterial agglutination. But in neutralization of toxins and viruses, it is less active than IgG. It helps in complement activation.
HEY-:)
Antibodies helps in removing or killing the germs or their secretions. Some characteristics of antibodies are as follows:
↪Antibodies is also called as immunoglobulins are proteins.
↪They are produced on exposure to antigen.
↪Their production is unlimited in human body.
↪They are specific.
↪They recognise and bind to a specific antigen.
↪Some antibody are present in the blood from the very birth.
↪Immunity produced by them may either be for short period (cold, cholera etc.,) or long period (smallpox, measles, etc).
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