Systemic Lupus Erythematosus (SLE) is an example of which type of hypersensitivity reaction?

Systemic Lupus Erythematosus (SLE) is classified as a Type 3 hypersensitivity reaction, which is characterized by the formation of immune complexes. In SLE, the body produces autoantibodies against various antigens, leading to the formation of these complexes. These immune complexes can deposit in various tissues, including the kidneys, skin, and joints, triggering an inflammatory response. The acute inflammation and subsequent tissue damage result from the activation of complement and the recruitment of inflammatory cells, which are mediated by these deposited immune complexes.

This type of hypersensitivity is distinct from other types such as Type 1, which involves IgE-mediated reactions, Type 2, characterized by antibody-mediated cytotoxicity, and Type 4, which is a delayed-type hypersensitivity mediated by T cells rather than antibodies. Understanding this classification helps to identify the mechanisms behind the pathology of SLE and the clinical manifestations associated with it.