William G. was well for the first ten months of his life, but in the following year he had pneumonia once, several cases of otitis media, and a streptococcal infection of the skin. All of these infections were treated successfully with antibiotics.
William was a bright, active child who gained weight, grew, and developed normally but continued to have repeated bacterial infections of the ears and sinuses and had pneumonia two more times before reaching the age of 30 months. Family history revealed that William’s mother had two brothers who died by the age of two due to repeated pneumonia infections. At this point, William’s physician tested his serum immunoglobulins with the following results: IgG 80 (normal 600 – 1500), IgA 0 (normal 50 – 125), IgM 10 (normal 75 – 150). William was prescribed monthly injections of gamma globulins to maintain a minimum level of IgG of 200.
William started school at age five, though he had prolonged absences due to recurrent pneumonia and other bacterial infections. At age nine, he was referred to a specialist due to partial lung collapse and chronic cough. The physician noted William had no visible tonsils despite the fact he never had a tonsillectomy but was otherwise normal for his age.
William eventually was diagnosed with X-linked agammaglobulinemia, a condition characterized by a lack of mature B cells.
a. Explain why do people with agammaglobulinemia have more trouble fighting bacterial infections than viral infections?
b. What might be the likely explanation for the fact that William was well for the first ten months of his life?
c. Explain why does William have to receive monthly injections of gamma globulins and not just a single injection?