<prompt> Autoimmunity is causedThe pressure of forbidden clonesExpression of cryptic antigensNegative selection of T-cells in the thymusInappropriate expression of the MHC proteins  <response>: Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues. Any disease that results from such an aberrant immune response is termed an autoimmune disease. Prominent examples include celiac disease, diabetes mellitus type 1, sarcoidosis, systemic lupus erythematosus SLE, Sjogrens syndrome, eosinophilic granulomatosis with polyangiitis, Hashimotos thyroiditis, Graves disease, idiopathic thrombocytopenic purpura, Addisons disease, rheumatoid ahritis RA, ankylosing spondylitis, polymyositis PM, and dermatomyositis DM. Autoimmune diseases are very often treated with steroids. 