Immunoglobulin A Subclasses

Overview

  • EPIC Code:
  • MISC
  • Soft Test Code:
  • MSOT
  • Send Out Test Code:
  • 34188
Alternate Names
  • IgA Subclasses
Included Tests

IgA1, IgA2, Total IgA


Clinical Significance

IgA Subclasses - IgA, the predominant immunoglobulin secreted at mucosal surfaces, consists of 2 subclasses. IgA1 is the major subclass and accounts for 80% of total IgA in serum, whereas IgA2 is the major subclass in secretions such as milk. Low concentrations of IgA2 with normal IgA1 levels suggest an IgA2 deficiency.
Antigenic sites on the IgA subclasses are responsible for the anaphylactic transfusion reactions experienced by some patients totally deficient in either IgA1 or IgA2. After repeated transfusions, such patients may produce antibodies to these antigens. Thus, IgA subclasses are useful in evaluating patients with anaphylactic transfusion reactions. Elevated concentrations of IgA2 with normal or low amounts of IgA1 suggest a clonal plasma cell proliferative disorder secreting a monoclonal IgA2. Grossly elevated levels of either subclass can occur in patients with IgA myeloma.
IgA subclasses are of further importance in certain pathogenic microorganisms, including Haemophilus influenzae, which are capable of enzymic cleavage of IgA1, leading to partial inactivation of this subclass. Recurrent sinopulmonary infections may, therefore, be related to deficiency of IgA2, which is resistant to these organisms


Specimen Collection & Preparation

Patient Preparation

Fasting Preferred


Specimen Requirements

2.0 mL Serum from a Red Top Tube in a Plastic Vial


Transport And Storage

5 days Ambient
15 days Refrigerated
30 days Frozen


Collection Instructions

Centrifuge within 1 hour of collection and immediately separate serum specimens from the cells


Minimum Volume

1.0 mL Serum


Neonatal Volume

Clinical Interpretation

Reference Range:

Refer to Interpretive Results


Methodology:
  • Immunoturbidimetry
Clinical Significance

IgA Subclasses - IgA, the predominant immunoglobulin secreted at mucosal surfaces, consists of 2 subclasses. IgA1 is the major subclass and accounts for 80% of total IgA in serum, whereas IgA2 is the major subclass in secretions such as milk. Low concentrations of IgA2 with normal IgA1 levels suggest an IgA2 deficiency.
Antigenic sites on the IgA subclasses are responsible for the anaphylactic transfusion reactions experienced by some patients totally deficient in either IgA1 or IgA2. After repeated transfusions, such patients may produce antibodies to these antigens. Thus, IgA subclasses are useful in evaluating patients with anaphylactic transfusion reactions. Elevated concentrations of IgA2 with normal or low amounts of IgA1 suggest a clonal plasma cell proliferative disorder secreting a monoclonal IgA2. Grossly elevated levels of either subclass can occur in patients with IgA myeloma.
IgA subclasses are of further importance in certain pathogenic microorganisms, including Haemophilus influenzae, which are capable of enzymic cleavage of IgA1, leading to partial inactivation of this subclass. Recurrent sinopulmonary infections may, therefore, be related to deficiency of IgA2, which is resistant to these organisms


Production Schedule

Sites Performed
  • Quest - Chantilly
Days Performed
Sunday
Monday
Tuesday
Wednesday
Thursday
Departments
  • Sendouts - Miscellaneous
Turn Around Time

1 to 4 days


Coding & Compliance

CDM

00913333


CPT Coding

82784, 82787 x2