IGG SUBCLASSES (1,2,3,4)

Code
900.2151
Name
IGG SUBCLASSES (1,2,3,4)
Category
None
Department
Send-Out
Start Date
Expiration Date
Synonyms
Immunoglobulin G Subclasses
CPT Codes
82787 X4
Site
SBMF
Reference Test
28297
ATLAS Test Code

Specimen Information

Type

Gold, SST

Volume

0.5 ml

Transport Info

Refrigerated

Fasting Required?
False
Patient Instructions

Reference Range

See report

Methodology

Nephelometry

Clinical Significance

A second order test for evaluation of selected patients with humoral or combined immunodeficiency
Also useful in some patients with hypogammaglobulinemia and those with possible immunodeficiency and normal total IgG levels.

There are four IgG subclasses, which account for approximately 75-80% of total serum immunoglobulin. The subclasses (IgG1 through IgG4) show different properties, including ability to fix complement, to bind to macrophages and to pass through the placenta. Of total IgG, 65% is IgG1, 25% is IgG2, 6% is IgG3 and 4% is IgG4. Decreased concentrations of IgG subclasses may occur in the context of hypogammaglobulinemia (i.e. common variable immunodeficiency, where all Ig classes are affected) or deficiencies may be selective, usually involving subclass IgG2. Deficiency of IgG2 can occur as an isolated deficiency or in combination with deficiency of IgA and other IgG subclasses. Most patients with IgG2 deficiency present with recurrent infections, such as, sinusitis, otitis or pulmonary infections. Children with IgG2 deficiency often have deficient antibody response to polysaccharide antigens including bacterial antigens associated with Haemophilus influenza and Streptococcus pneumoniae.

Comment: IgG subclasses measurement is not a first order test in patients suspected of having immunodeficiency. Quantitation of total IgG, IgA and IgM levels along with other first order tests (including lymphocyte counts, etc.) should be performed first.

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