Immunoglobulins have been used for long time in prophylaxis or management of various infections. The administration of immunoglobulins is known as passive immunization, which is used to provide temporary immunity under following situations:
- in a unimmunized person exposed to infection;
- in a person who has been infected from a disease for which active immunization is not available.
Two types of immunoglobulins have been available, ones of animal origin (antitoxin/antisera) and others of human origin. Human immunoglobulins have replaced immunoglobulins of animal origin, which were frequently associated with hypersensitivity reactions. Injection of immunoglobulin produces immediate protection lasting for several weeks. Thus the immunoglobulins are classified as below:
- Specific Immunoglobulins of animal origin (antisera/antitoxin).
- Normal human immunoglobulins
- Specific human immune serum immunoglobulin with a known quantity of antibody to specific antigen.
Immunoglobulins of animal origin:
Today immunoglobulins derived from horse serum are used only in cases of diphtheria and are known Diphtheria Antitoxin. Prompt administration is beneficial in the management of respiratory diphtheria.
For mild early pharyngeal or laryngeal disease the dose is 20000-40000 units; for moderate nasopharyngeal disease 40000-60000 units; for severe, extensive, or late (3 days or more) disease 80000-100000 units. As the reactions are common after administration, resuscitation facility should make available by the bed side of the patient before starting administration.
Antitoxin is no longer used for prophylaxis. Unimmunized contacts should be promptly investigated and given vaccine and antibacterial prophylaxis.
Human immunoglobulins are produced from pooled human plasma or serum, and are tested and found non reactive for hepatitis B surface antigen and antibodies against hepatitis C virus and human immunodeficiency virus (type 1 and 2).
Two types of immunoglobulins are being used for immunization purposes viz (a) Normal Immunoglobulin, b) Specific Immunoglobulin.
Normal Immunoglobulins: It is prepared from pools of donations of human plasma or serum. It contains antibodies to viruses that are currently prevalent in the general population, common being measles, mumps, rubella and hepatitis A etc.
Normal immunoglobulins is administered by intramuscular injection for susceptible contacts against hepatitis A virus (infections hepatitis), measles and to a lesser extent rubella.
Normal immunoglobulins may interfere with the immune response to live virus vaccines which should therefore only be given at least 3 weeks before or 3 months after an injection of normal immunoglobulin with the exception of yellow fever since normal immunoglobulin does not contain antibody to this virus.
Normal immunoglobulins are contraindicated in patients known to have class specific antibodies to immunoglobulin A.
i) Hepatitis A:Intra muscular; normal immunoglobulin is of value in the prevention of infection in close contacts of confirmed cases of Hepatitis A, where there has been delay of more than 7 days in identifying contacts, or for close contacts at high risk of severe disease. It may also be used in immuno-compromised patients as their antibody response to vaccine is unlikely to be adequate.
DOSE: 0.2-0.4mg/Kg IM (only once)
: 0.6mg/Kg every 5 months if there is continuous exposure to the infection
Now normal immunoglobulin in no longer used for routine prophylaxis.
ii) Measles: intramuscular normal immunoglobulin may be given to prevent or attenuate an attack of measles, in individuals who do not have adequate immunity. Children and adults with compromised immunity who have come into contact with measles should receive intramuscular normal immunoglobulins as soon as possible after exposure. It is most effective if given within 72 hours but can be effective if given within 6 days. For individuals receiving intravenous immunoglobulin, 100 mg/kg given within 3 weeks before measles exposure should prevent measles. Intramuscular normal immunoglobulin should also be considered for the following individuals if they have been in contact with a confirmed case of measles or with a person associated with a local outbreak.
- non-immune pregnant women;
- infants under 9 months.
Individuals with normal immunity who are not in the above categories and who have not been fully immunized against measles, can be given measles vaccine for prophylaxis following exposure to measles.
iii) Rubella: Intramuscular immunoglobulin after exposure to rubella does not prevent infection in non-immune contact and is not recommended for protection of pregnant women exposed to rubella. It may, however, reduce the likelihood of a clinical attack which may possibly reduce the risk to the fetus. It should be used only if termination of pregnancy would be unacceptable to the pregnant woman, when it should be given as soon as possible after exposure. Serological follow-up of recipients is essential to determine if the woman has become infected despite receiving immunoglobulin.