Differences between Active Immunity and Passive Immunity

 

Differences between Active Immunity and Passive Immunity

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The major differences are:

S.N.	Characteristics	Active Immunity	Passive Immunity
1.	Definition	The protective immunity in which the individual’s own immune system is stimulated to produce antibodies and lymphocytes.	The immunity in which a person receives antibodies or lymphocytes that have been produced by another individual’s immune system.
2.	Exposure to Antigen	Requires exposure to a pathogen or to the antigen of a pathogen.	Does not require exposure to an infectious agent or its antigen.
3.	Immune system involvement	The immune system of the individual is actively involved in the process.	The immune system of the individual is not actively involved but rather passive.
4.	Natural acquirement	Arise naturally when an individual is exposed to an antigen or pathogen (clinical infection).	Arise naturally when a fetus receives antibodies from the mother across the placenta or when a breast-feeding infant ingests antibodies in the mother’s milk.
5.	Artificial acquirement	Conferred artificially by means of vaccines.	Conferred artificially by administration of preformed antibodies.
6.	Immunity type	Involves both humoral and cell mediated immunity.	The immunity is conferred only by readymade antibodies.
7.	Components	T cells (cytotoxic T cells, helper T cells, memory T cells, and suppressor T cells), B cells (memory B cells and plasma cells), and antigen-presenting cells (B cells, dendritic cells, and macrophages).	No immune cells are involved as antibody is preformed.
8.	Antibody production	Involves antibody production which is induced by infection or immunogen.	No antibody is produced, but directly transferred.
9.	Memory cell formation	Active immunity results in the formation of long-lasting memory cells.	Memory immune cells are not formed.
10.	Secondary response	The first exposure leads to primary response and incase of a subsequent exposure to same pathogen later, a much faster and stronger secondary response is established.	Absence of a secondary response.
11.	Durability	The protection offered is long-lived.	The protection is only transient.
12.	Response time	The protective response takes time to establish as a lag period is present.	No lag period hence the protection is instant.
13.	Reactivation	Reactivated by recurrence of infection or by revaccination.	Frequent re-administration needed for renewed protection.
14.	Booster effect	Subsequent doses with antigens cause booster effect.	Subsequent doses are less effective due to immune elimination.
15.	Suitability	Active immunity is not suitable for protection of immuno-compromised or immuno-deficient individuals.	Passive immunity is useful in cases of immuno-compromised, immuno-deficient or severe combined immunodeficiency.
16.	Use	Very effective for prophylaxis of diseases.	Artificial passive immunity is effective as a post-exposure remedy.
17.	Effectiveness of Protection	Provides effective protection.	Protection rendered is less effective and may not be complete.
18.	Adverse effect	It can be implicated in autoimmune diseases and allergies, but generally does not have side effects.	A condition called serum sickness can result from exposure to antisera.
19.	Examples	Natural – Producing antibodies in response to exposure to a pathogenic infection such as measles or cold. Artificial – Producing antibodies in response to the controlled exposure to an attenuated pathogen (i.e. vaccination).	Natural – Receiving antibodies from another organism (e.g. to the foetus via the colostrum or a newborn via breast milk). Artificial – Receiving manufactured antibodies via external delivery (e.g blood transfusions of monoclonal antibodies).