Fundamentals of Nursing Q 522
Nurse Berta is facilitating a monthly mothers’ class at a small village. As a knowledgeable nurse, she must know that a mother who breastfeeds her child passes on which antibody through breast milk?
A. IgA
B. IgE
C. IgG
D. IgM
Correct Answer: A. IgA
Antibodies, which are also called immunoglobulins, take five basic forms, indicated as IgG, IgA, IgM, IgD and IgE. All have been detected in human milk, but by far the most abundant type is IgA, particularly the form known as secretory IgA, which is found in great amounts throughout the gut and respiratory system of adults. The secretory IgA molecules passed to the suckling child are helpful in ways that go beyond their ability to bind to microorganisms and keep them away from the body’s tissues.
Option B: IgE is a monomer. It has a molecular weight of 188 Kd and a serum concentration of 0.00005 mg/mL. It protects against parasites and also binds to high-affinity receptors on mast cells and basophils causing allergic reactions. IgE is regarded as the most important host defense against different parasitic infections which include Strongyloides stercoralis, Trichinella spiralis, Ascaris lumbricoides, and the hookworms Necator americanus and Ancylostoma duodenal.
Option C: IgG2 forms an important host defense against bacteria that are encapsulated. IgG is the only immunoglobulin that crosses the placentae as its Fc portion binds to the receptors present on the surface of the placenta, protecting the neonate from infectious diseases. IgG is thus the most abundant antibody present in newborns.
Option D: IgM has a molecular weight of 970 Kd and an average serum concentration of 1.5 mg/ml. It is mainly produced in the primary immune response to infectious agents or antigens. It is a pentamer and activates the classical pathway of the complement system. IgM is regarded as a potent agglutinin (e.g., anti-A and anti-B isoagglutinin present in type B and type A blood respectively) and a monomer of IgM is used as a B cell receptor (BCR).