Molecular and Cellular Basis of Immunity and Immunological Diseases.

The immune system can be divided into innate and adaptive subsystems whose inappropriate activation leads to autoinfl ammatory and autoimmune diseases, respectively. Many rheumatic diseases are a combination of both processes.The innate immune system is activated by specific receptors that recognize patterns associated with pathogens, which activate a program of infl ammation involving hundreds of genes.Cells of the innate immune system, including dendritic cells, natural killer (NK) cells, mast cells, eosinophils, and basophils, activate and modulate the adaptive immune response, directly combat pathogens, and respond to allergens.The adaptive immune response depends on antigen recognition by T and B cells, whose cell surface receptors are highly variable to respond to environmental insults. Normally, adaptive immune cells are tolerant to self.Different subsets of T lymphocytes, including Thelper, cytotoxic T cells, and T-regulatory cells, modulate the immune response to effectively combat pathogens yet limit autoimmunity. Dysregulation of T-cell function is seen in autoimmune disease.■ Antibody-producing B lymphocytes recognize and present soluble antigens. Autoantibodies contribute signifi cantly to autoimmune diseases. [ABSTRACT FROM AUTHOR]