Immunoglobulin G (IgG), Serum/Plasma

Immunoglobulin G (IgG) is a multimeric immunoglobulin, built of two heavy chains γ and two κ or λ light chains and has four subclasses; 1 the most abundent to 4 the least abundent. Each complex has two antigen binding sites. This is the most abundant immunoglobulin and is approximately equally distributed in blood and in tissue liquids, constituting 75% of serum immunoglobulins in humans. IgG can bind to many kinds of pathogens, for example viruses, bacteria, and fungi, and protects the body against them by complement activation (classic pathway), opsonization for phagocytosis and neutralisation of their toxins. It is the only isotype that can pass through the human placenta, thereby providing protection to the fetus in its first weeks of life before its own immune system has developed. IgG can cause food allergy, and in such causes delayed-onset food allergy, in contrast to food allergy by IgE, whose effects appear rapidly.

As a normal result of infection all immunoglobulin classes including IgG increase in serum. In addition, IgG levels rise in autoimmune disorders, and chronic hepatitis. These increases are result of polyclonal expansion of immunoglobulin producing cells. On the other hand, malignant cell proliferation of an immunoglobulin producing cell results in an increase in immunoglobulin serum level termed monoclonal gammopathy. Decreased immunoglobulin levels are seen in patients with protein loss syndrome, inherited deficiency or may be secondary to lymphoid malignancies.

1 ml Serum 1 ml Li-Heparin or K2-EDTA Plasma Stability: 4 Months at 15-25 °C 8 Months at 2-8 °C 8 Months at (-15)-(-25) °C

Adults: 7-16 g/L (46.7-107 μmol/L) Children/ juveniles: 0‑14 days: 3.20-12.1 g/L (21.3-80.4 μmol/L) 15 days - < 1 yr: 1.48-6.31 g/L (9.87-42.1 μmol/L) 1 - < 4 yr: 3.17- 9.94 g/L (21.1-66.3 μmol/L) 4 - < 10 yr: 5.01-11.7 g/L (33.4-77.7 μmol/L) 10 - < 19 yr: 5.95-13.1 g/L (39.7-87.2 μmol/L)