A full-term baby boy is delivered after an uneventful pregnancy, and is well for the first 2 years of his life. He receives all his immunizations without any complications. Staing around his 2nd bihday, the mother begins to note frequent upper respiratory tract infections, and the child is hospitalized three times for pneumonia. Laboratory testing would most likely reveal a deficiency of which of the following immunoglobulins in this child?
Selective IgA deficiency ( IgD has not been given any paicular function other than to act as a receptor on the B cell. It can be found in very low levels in serum. IgG is the major immunoglobulin found in the humoral immune response. A patient with a low IgG will experience pyogenic infections. IgM is found in the early response to an antigen. If the patient was deficient in IgM he would have also been characteristically low in IgG and would have experienced recurrent pyogenic infection, usually commencing by the age of 5-6 months.
IgA
IgD
IgG
IgM