Immunologic tests of value in diagnosis. 1. Acute phase reactants and autoantibodies.

Acute phase reactants are nonspecific indicators of tissue necrosis and/or inflammation but may be helpful in determining activity of disease. Rheumatoid factor is likewise rather nonspecific, but its presence is helpful in predicting the course, severity, and complications of rheumatoid arthritis. Numerous antinuclear antibodies have been identified in collagen vascular diseases; perhaps the most specific association is between anti-Sm antibody and systemic lupus erythematosus. Anti-smooth-muscle and antimitochondrial antibodies can aid in differential diagnosis of liver disease, while antithyroid antibodies can perform a similar function in diffuse goiter. Anti-parietal-cell and anti-intrinsic-factor antibodies are quite specific for pernicious anemia.