IgG Subclasses

While all the IgG subclasses contain antibodies to components of many disease-causing bacteria and viruses, each subclass serves a slightly different function in protecting the body against infection. For example, IgG1 and IgG3 subclasses are generated against proteins such as the toxins generated by the diphtheria and tetanus bacteria, as well as antibodies against viral proteins. In contrast, IgG2 antibodies are predominantly against the polysaccharide (complex sugar) coating (capsule) of certain disease-producing bacteria (such as, Streptococcus pneumoniae and Haemophilus influenzae).

Patients with recurrent infections may still present with normal or elevated IgG levels making diagnosis of immune deficiency difficult. In these circumstances IgG subclass measurements may be a useful tool for diagnosis of PID alongside Vaccine Response tests.

IgG4 subclass measurement is also a useful serological marker for IgG4 related disease. This relatively new class of inflammatory conditions is characterized by tumefactive lesions and elevated serum IgG4. The measurement of serum IgG4 is a useful tool for both diagnosis and responsiveness to steroid treatment.

Binding Site provides automated solutions for the measurement of IgG Subclasses on the Optilite^®