Immunoglobulin A (IgA) is the major immunoglobulin present in milk.
While IgA is the predominant immunoglobulin in milk, especially in colostrum and milk of most species, including humans, it's important to note that other immunoglobulins, such as IgM, are also present. These immunoglobulins, IgA and IgM, are often found in the form of secretory IgA (sIgA) and secretory IgM (sIgM), respectively. These secretory forms are produced by plasma cells located in the mammary tissue.
Therefore, while IgA is the most abundant, milk isn't solely comprised of IgA. The presence of other immunoglobulins contributes to the overall immune protection that milk provides to newborns.
