α1-antitrypsin (AAT) is a monomeric glycoprotein that belongs to the serpin family (“SERine Protease INhibitor”). The encoding gene (SERPINA1 or PI-“Protease Inhibitor”) is located on chromosome 14. AAT inhibits several serine proteases, but the main target is neutrophil elastase (NE), an enzyme released by neutrophils that is responsible for the proteolysis of many components of the extracellular matrix, including elastin. When neutrophils are activated, NE is released into lung tissue, where, if not inhibited, it manifests its proteolytic activity. The reference values in plasma for adults, according to the IFCC international standardization (CRM 470), are 0.9–2.0 g/L. AAT deficiency is an autosomal recessive disorder, which increases the risk of developing some diseases, among which the most important for its social relevance are lung diseases (chronic obstructive pulmonary disease, emphysema) and liver diseases (liver fibrosis, cirrhosis, liver carcinoma). The diagnosis of the genetic defect is prerogative of specialized centers. In the general population, the occasional finding of a plasma concentration of AAT <1 g/L by immunometric measurement makes it necessary to confirm the data through quantitative and qualitative tests in specialized laboratories. AAT migrates in the α1 zone of the S-EF (Fig. 1); the occasional finding of two separate bands in this zone (heterozygosity of AAT) or of the absence of the α1-globulin peak or of a percentage of the α1 zone lower than the reference values must be followed by the immunometric measurement of AAT on the sample. If the plasma concentration of AAT is below the lower reference limit, an in-depth diagnostic examination with qualitative and genetic tests at specialized laboratories is necessary. The main indications for the request are early emphysema, bronchiectasis without obvious etiology, hepatopathy not otherwise explainable, first-degree relatives of patients with ascertained deficiency. Since AAT is an acute-phase protein, it is advisable to simultaneously measure an acute-phase marker, such as C-reactive protein, to exclude an increase in AAT linked to an ongoing inflammatory phenomenon, which could mask the presence of a possible deficiency.

Fig1. Serum protein path performed on agarose gel In the migration positions of the main serum proteins are indicated.

مواضيع ذات صلة

Albumin

Diagnostic Laboratory Tests for Mycobacterium Tuberculosis

Glucose, blood (Blood sugar, Fasting blood sugar [FBS])

Gliadin, endomysial, and tissue transglutaminase antibodies

Antimicrobial Susceptibility Testing and Therapy of Staphylococcus, Micrococcus, and Similar Organisms

Glucagon

genetic testing (Breast cancer [BRCA] and ovarian cancer, Colon cancer, Cardiovascular disease, Tay–Sachs disease, Cystic fibrosis, Melanoma, Hemochromatosis, Thyroid cancer, Paternity [parentage analysis], Forensic genetic testing)

Tuberculin Test

Clinical Relevance of Plasma Cell Dyscrasias

Liver Cancers

Biomarkers of Alcoholism

Gastrin