14 Facts About Passive immunity

Passive immunity is the transfer of active humoral immunity of ready-made antibodies.

Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can be induced artificially, when high levels of antibodies specific to a pathogen or toxin are transferred to non-immune persons through blood products that contain antibodies, such as in immunoglobulin therapy or antiserum therapy.

Maternal passive immunity is a type of naturally acquired passive immunity, and refers to antibody-mediated immunity conveyed to a fetus or infant by its mother.

Naturally acquired passive immunity can be provided during pregnancy, and through breastfeeding.

Maternal passive immunity offers immediate protection, though protection mediated by maternal IgG typically only lasts up to a year.

Passive immunity is provided through colostrum and breast milk, which contain IgA antibodies that are transferred to the gut of the infant, providing local protection against disease causing bacteria and viruses until the newborn can synthesize its own antibodies.

Artificially acquired passive immunity is a short-term immunization achieved by the transfer of antibodies, which can be administered in several forms; as human or animal blood plasma or serum, as pooled human immunoglobulin for intravenous or intramuscular use, as high-titer human IVIG or IG from immunized donors or from donors recovering from the disease, and as monoclonal antibodies.

Passive immunity transfer is used to prevent disease or used prophylactically in the case of immunodeficiency diseases, such as hypogammaglobulinemia.

Passive immunity provides immediate protection, but the body does not develop memory; therefore, the patient is at risk of being infected by the same pathogen later unless they acquire active immunity or vaccination.

One exception to passive humoral immunity is the passive transfer of cell-mediated immunity, called adoptive immunization which involves the transfer of mature circulating lymphocytes.

However, this specialized form of passive immunity is most often used in a laboratory setting in the field of immunology, to transfer immunity between "congenic", or deliberately inbred mouse strains which are histocompatible.

An individual's immune response of passive immunity is "faster than a vaccine" and can instill immunity in an individual that does not "respond to immunization", often within hours or a few days.

Disadvantage to passive immunity is that producing antibodies in a laboratory is expensive and difficult to do.

Passive immunity is effective, but only lasts a short amount of time.