• Immunoglobulin G ( IgG)

(i) IgG is the major serum immunoglobulin (about 80% of the total amount). The normal serum concentration is about 8-16 mg/ml.

(ii) Molecular weight is 150,000 (7S)

(iii) Half life is about 23 days (longest amongst all the immunoglobulins).

(iv) It is the only immunoglobulin that is transport through placenta and provides natural passive immunity to newborn.

(v) It is distributed equally between extravascular and intravascular compartments.

(vi) IgG appears late but persists for longer period. It appears after the initial immune response which is IgM in nature.

(vii) It participates in precipitation, complement fixation and neutralization of toxin and viruses.

(viii) It is protective against those microorganisms which are active in the blood and tissues.

Source – textbook of microbiology C P Baveja