Immunoglobulin heavy constant alpha 2

Immunoglobulin heavy constant alpha 2 (IgA2) is the predominant immunoglobulin in secretory IgA (sIgA), the primary adaptive immune defence of oral and gastrointestinal mucosal surfaces. Salivary sIgA-IgA2 levels reflect mucosal immune competence and are suppressed by intense training loads, psychological stress, and energy deficit, increasing susceptibility to upper respiratory tract infections. It is a well-validated marker of mucosal immunity in elite sport.