The primary immunoglobulin present in breast milk is IgA (Immunoglobulin A).
Breast milk, particularly colostrum (the early milk produced after birth), is rich in antibodies that help protect the newborn from infections. While other immunoglobulins like IgM and IgG are present in lower concentrations, IgA is the most abundant and crucial for providing passive immunity to the infant.
IgA's Role in Infant Immunity
- Protection against Infections: IgA primarily defends against respiratory and gastrointestinal infections, common threats to newborns.
- Neutralization of Pathogens: It works by neutralizing pathogens, preventing them from attaching to the infant's mucosal surfaces (e.g., the lining of the gut and respiratory tract).
- Passive Immunity: Because the infant's own immune system is still developing, IgA from breast milk provides vital passive immunity.
Other Immunoglobulins in Breast Milk
While IgA is dominant, smaller amounts of IgM and IgG are also present:
- IgM (Immunoglobulin M): Contributes to overall immune defense.
- IgG (Immunoglobulin G): Found in higher levels in colostrum than in mature milk, providing additional early protection.
In summary, while breast milk contains a mixture of immunoglobulins, IgA is the most significant and abundant antibody contributing to the passive immune protection of the newborn.
