Immunoglobulins are proteins produced by cells called lymphocytes. They act as a first line defense against infections. Immunoglobulin preparations are made from humans for commercial use. The protection afforded is usually temporary (usually up to a few weeks). Let us see what preparations are available for protection against diseases.
a) Normal human Ig:
Normal human Ig is an antibody–rich fraction obtained from a pool of at least 1000 donors. The diseases against which the immunoglobulin preparations are effective include Hepatitis A, measles, Normal human Ig is used to prevent measles in highly susceptible individuals and to provide temporary protection (up to 12 weeks) against hepatitis B infection for travelers to endemic areas and to control institutional & household outbreaks of hepatitis A infection.
b) Specific human Ig:
These preparations are made from the plasma of patients who have recently recovered from an infection or are obtained from individuals who have been immunized against a specific infection. They therefore have a high antibody content against an individual infection and provide immediate protection e.g. specific human Igs are used for chickenpox prophylaxis of highly susceptible individuals and for post exposure prophylaxis of hepatitis B, and rabies and for tetanus prophylaxis in the wounded. Immunoglobulin is usually administered by intramuscular injection.
What are antisera?
Immunoglobulin preparations obtained from animals are called antisera e.g.tetanus, diphtheria, botulism, gas gangrene and snake bite. The antisera have a higher rate of complications than the human immunoglobulins. Hypersensitivity reactions, serum sickness can be seen. Doses of antisera for tetanus and gas gangrene.
|Tetanus||The usual prophylactic dose is 1,500 units of horse A.T.S. given subcutaneously or intramuscularly, soon after injury.|
|Gas gangrene||A patient who has sustained a wound possibly contaminated with spores of gas gangrene should receive a dose of 10,000 I.U. of CI porringers (Cal wheelchair) antitoxin, 5,000 units of CL septic antitoxin and 10,000 units of CL federations antitoxin, intramuscularly or in urgent cases intravenously.|
Precautions to be taken
Before administration of the antiserum or antitoxin it is necessary to test for sensitivity reaction. Testing is by intra–dermal injection of a small quantity of the antiserum (0.2 ml of antiserum diluted 1:10 with saline). A skin reaction at the site of injection called wheal and flare is seen if the person is sensitized. Testing should be done at a place which has emergency drugs available in the rare case of a severe reaction.