In the last section of this chapter, we willĮxamine the mechanisms by which self-tolerance is lost and autoimmune responses areġ3-1. This section, we will examine the nature of autoimmune responses and howĪutoimmunity leads to tissue damage. Sustained and cause lasting tissue damage that they attract medical attention. Transient autoimmune responses are common, but it is only when they are It is not known what triggers autoimmunity,īut both environmental and genetic factors, especially MHC genotype, are clearly These repertoires are purged of most receptors that bind with high affinity to selfĪntigens encountered during development, they still include receptors of lowerĪffinity reactive to some self antigens. T-cell help to self-reactive B cells can initiate harmful autoantibody responses.Īutoimmune responses are a natural consequence of the open repertoires of bothī-cell and T-cell receptors, which allow them to recognize any pathogen. T H1 cells can cause extensive tissue damage, whereas inappropriate Responses to self antigens can inflict tissue damage either directly or indirectly.Ĭytotoxic T-cell responses and inappropriate activation of macrophages by The immunopathological (more.)Īdaptive immune responses are initiated by the activation of antigen-specific T cells, and it is believed that autoimmunity is initiated in the same way. Autoimmune diseases can be grouped in the same way as hypersensitivity reactions, according to the type of immune response and the mechanism by Some commonĪutoimmune diseases classified by the mechanism of tissueĭamage.

Operate in protective immunity and in hypersensitivity diseases. Of tissue damage in autoimmune diseases are essentially the same as those that The consequence is that the effector pathways of immunityĬause chronic inflammatory injury to tissues, which may prove lethal. Immune response develops against self antigens, however, it is usually impossibleįor immune effector mechanisms to eliminate the antigen completely, and so a

Virus-infected cells,įor example, are destroyed by cytotoxic T cells, whereas soluble antigens areĬleared by formation of immune complexes of antibody and antigen, which are taken upīy cells of the mononuclear phagocytic system such as macrophages. The normal consequence of an adaptive immune response against aįoreign antigen is the clearance of the antigen from the body. Autoimmune disease occurs when a specific adaptive immune response is mounted against

Massive attack level 4