Passive Immunization

 Passive Immunization 

Passive immunization is administration of purified antibodies or serum containing antibodies to provide, rapid and temporary protection at the time of emergency (i.e when individuals immune system is unable to provide resistance against infection).

For example; newborn receive natural passive immunity from mother's antibodies (immunoglobulins) that can cross placenta IgG or it is also present in mother's milk IgA.

Passive immunization is done by sera which contains antibodies - it involves human sera and animal sera.

It is considered necessary to give immediate protection to an anticipated infection.

For example;

Passive immunization against tetanus, hepatitis B and rabies.

Passive immunization is used to;

1. Prevent disease after a known exposure.

For example; needle stick injury with blood that is contaminated with Hepatitis B virus.

2. Protect immunodeficient individuals who are incapable of making an immune response.

Three types of preparation are available for passive Immunization;

1. Pooled immunoglobulin

2. Specific immunoglobulin

3. Homologous and heterologous sera

1. Pooled immunoglobulin

It is prepared from plasma of approximately a thousand or more blood donors.

Containing high level of antibodies.

Human normal immunoglobulin (HNIG) is used in short term prophylaxis against hepatitis A and measles.

2. Specific immunoglobulin

It is prepared from serum of patients who are recovering from infection.

Specific immunoglobulins are available against tetanus as human tetanus immunoglobulin (HIIG).

Hepatitis B as hepatitis B human immunoglobulin (HBIG)

Rabies as human rabies immunoglobulin (HRIG)

Varicella zoster as zoster immunoglobulin (ZIG).

3. Homologous and heterologous sera

Antibacterial, antiviral, antibodies in human (homologous) or animal (heterologous) serum are injected to provide temporary protection against infection.