IgA (Serum)

Immunoglobulin A (IgA) is a major antibody isotype found predominantly in mucosal secretions (e.g., saliva, tears, respiratory and gastrointestinal mucus) and also in serum. It plays a critical role in mucosal immunity, providing the first line of defense against inhaled and ingested pathogens. Serum IgA levels can be affected by various conditions. Selective IgA deficiency is the most common primary immunodeficiency.