Immunoglobulin G2 (IgG2)

Oxelius et al. (1981) pointed out that deficiency of IgG2 in combination with IgA deficiency is a critical factor in whether or not IgA-deficient persons have illness (frequent infections, autoimmune disorders, atopy, malabsorption). No allotypes are known on gamma-4 or on gamma-2. The reason may be the test system. Anti-D antiserum is used and this antibody is usually gamma-1 or gamma-3. Patients with IgG2 deficiency have recurrent sinopulmonary infections caused by Pneumococcus and Hemophilus. Tashita et al. (1998) studied 2 Japanese brothers, ages 5 and 10 years and found that both brothers were homozygous for a 1-bp insertion (1793insG) in exon 4 of the IGHG2 gene, just upstream from the alternative splice site for M exons . IgG2 23%; no Crosses placenta easily; third highest Complement activator; extremely low affinity Binds to Fc receptor on phagocytic cells