What is the Difference Between Hypersensitivity and Autoimmunity?

Hypersensitivity and autoimmunity are both defective immune responses, but they differ in their specific manifestations and triggers. Here are the key differences between the two:

• Hypersensitivity is an exaggerated and inappropriate immune response to an antigenic stimulus, which can be triggered by both endogenous and exogenous antigens. It includes immediate-type (allergy), delayed-type, and autoimmunity. A large proportion of the population is affected by one or more types of hypersensitivity, and it can manifest as acute or chronic conditions.
• Autoimmunity is a type of hypersensitivity to self-antigens that only affects approximately 5% of the population. It is an adaptive immune response mounted against self-antigens, and it is only triggered by endogenous antigens. Autoimmunity manifests as chronic problems due to the failure of immunological tolerance mechanisms and the continuous presence of self-antigens.

In summary, the main difference between hypersensitivity and autoimmunity is that hypersensitivity is an exaggerated immune response to various antigens, while autoimmunity is a specific type of hypersensitivity directed against the body's own antigens.

Comparative Table: Hypersensitivity vs Autoimmunity

Here is a table comparing hypersensitivity and autoimmunity:

Hypersensitivity reactions are maladaptive immune responses toward harmless foreign particles or self-antigens, and they occur after tissue sensitization. Autoimmunity, on the other hand, refers to the failure of immunological tolerance mechanisms, causing reactions against own cells and tissues.