Alphaglobulins

Alphaglobulins are a subset of plasma proteins that migrate in the alpha region during serum protein electrophoresis. They comprise several distinct proteins with varied functions, including protease inhibition, metal transport, and acute-phase responses.

The alpha-1 globulin group includes proteins such as alpha-1 antitrypsin (AAT) and alpha-1 acid glycoprotein (orosomucoid). The alpha-2 globulin group includes alpha-2 macroglobulin, haptoglobin, ceruloplasmin, and alpha-2-HS glycoprotein (fetuin-A). These proteins participate in protease inhibition, transport of metals, and modulation of immune and inflammatory processes.

Functions attributed to alphaglobulins are diverse. Alpha-1 antitrypsin inhibits neutrophil elastase and protects tissues, especially in the lungs. Alpha-1 acid glycoprotein acts as an acute-phase reactant with immunomodulatory roles. Haptoglobin binds free hemoglobin released during red blood cell turnover. Ceruloplasmin carries copper and has ferroxidase activity. Alpha-2 macroglobulin is a broad-spectrum protease inhibitor, and alpha-2-HS glycoprotein has roles related to mineral metabolism and inflammation.

Clinical significance includes changes in alphaglobulin levels during disease states. Many alphaglobulins rise in acute inflammation, while deficiencies of alpha-1 antitrypsin can lead to early-onset emphysema and liver disease. Abnormal alphaglobulin levels can aid in evaluating inflammatory conditions, liver disease, and certain genetic disorders. Electrophoretic profiling and immunoassays are used to assess individual alphaglobulins and interpret associated clinical conditions.

Measurement is typically performed by serum protein electrophoresis, where alphaglobulins constitute the front portion of the alpha region, with quantification supported by nephelometry or immunoassays.