IgG

noun

ˌī-(ˌ)jē-ˈjē 

1

: a class of immunoglobulins including the most common antibodies circulating in the blood that facilitate the phagocytic destruction of microorganisms foreign to the body, that bind to and activate complement, and that are the only immunoglobulins to cross over the placenta from mother to fetus

2

: an antibody of the class IgG

Examples of IgG in a Sentence

Recent Examples on the Web

In the absence of active lesions to swab for HSV itself, tests must evaluate the immune response to the virus in a patient’s blood, typically by screening for the immunoglobulin G (IgG) antibody. — Lauren Schneider, Scientific American, 9 June 2026

Confirming the diagnosis requires laboratory testing, typically through detection of specific antibodies (IgM or IgG) in a serum sample. — Matthew Binnicker, Forbes.com, 5 May 2026

It’s also known to contain lactoferrin, a protein with immune-supporting properties, and immunoglobulin G (IgG), a type of antibody. — New Atlas, 6 July 2025

The measles immunity test, or measles IgG antibody test, shows whether your immune system has developed protection against the measles virus, Sonora Quest officials say. — Stephanie Innes, AZCentral.com, 18 June 2025

In the blood, two types of antibodies (IgA and IgG) increased by several fold after vaccination compared with the placebo group. — Ars Technica, 6 Mar. 2025

Other serology tests are designed to detect IgG antibodies, which take longer for the body to produce but function to provide longer term immunity. — Matthew Binnicker, Forbes, 7 Sep. 2024

The most common components of colostrum supplements are immunoglobulins (especially IgG), growth factors, and lactoferrin. — Isabel Vasquez Rd Ldn, Health, 2 July 2024

Mice given IgG from these patients, as well as healthy controls, then underwent a battery of tests. — Byjennifer Couzin-Frankel, science.org, 21 June 2024

Word History

First Known Use

1965, in the meaning defined at sense 1

Medical Definition

IgG

noun

ˌī-ˌjē-ˈjē 

1

: a class of immunoglobulins that include the most common antibodies circulating in the blood, that facilitate the phagocytic destruction of microorganisms foreign to the body, that bind to and activate complement, and that are the only immunoglobulins to cross over the placenta from mother to fetus

2

: an immunoglobulin of the class IgG