Autoimmunity occurs when the immune system mistakenly targets the body's own tissues. Histological analysis of autoimmune diseases involves identifying characteristic patterns of tissue damage and immune cell infiltration. For example, in rheumatoid arthritis, synovial tissue shows hyperplasia and a dense infiltrate of lymphocytes and plasma cells. Similarly, in systemic lupus erythematosus (SLE), immune complex deposition and inflammation can be observed in various tissues.
