Immunoglobulin G

Immunoglobulin G or IgG is a the most common class of antibody in human blood, making up 80% of the antibodies, and is also found in tissue spaces.

Function
IgG is the only antibody that can cross the placenta, giving unborn and new born babies protection against contagious diseases and other infections.

ME/CFS
IVIG or intravenous immunoglobulin G is a treatment that has been investigated for ME/CFS, with positive results shown for some patients.

Fibromyalgia
In 2021, Goebel et al. published research showing that fibromyalgia may be an immune system disease mediated by IgG; in an animal study on mice they found that the mice developed pain and cold intolerance symptoms consistent with fibromyalgia after receiving IgG from the blood of patients with fibromyalgia.

Long COVID
Cervia et al. (2022) found that both IgG3 and IgM, when combined with other factors including age, presence of five symptoms (fever, fatigue, cough, shortness of breath, gastrointestinal symptoms during COVID-19 infection), acted as biomarkers to predict who would develop Long COVID after SARS-CoV-2 infection.

Notable studies

 * 2022, Immunoglobulin signature predicts risk of post-acute COVID-19 syndrome - (Full text)

News and articles
"'Andersson and his colleagues harvested blood from 44 people with fibromyalgia and injected purified antibodies from each of them into different mice. The mice rapidly became more sensitive to pressure and cold, and displayed reduced grip strength in their paws. Animals injected with antibodies from healthy people were unaffected.'" Prof Camilla Svensson from the Karolinska Institute in Sweden, who was also involved in the study, said: "'Antibodies from people with fibromyalgia living in two different countries, the UK and Sweden, gave similar results, which adds enormous strength to our findings.'"

Notable studies

 * 2021, Passive transfer of fibromyalgia symptoms from patients to mice

Learn more

 * Overview of specific adaptive autoimmunity - OpenStax
 * The Immune Response against Pathogens - OpenStax