A 3-year-old boy has had numerous bacterial infections, including respiratory infections with Hemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus since infancy. He develops a polyarthritis that clears with immunoglobulin therapy. A lymph node biopsy is performed, and microscopically the germinal centers of his nodes are rudimentary. During the 3rd decade of his life he develops systemic lupus erythematosus. He demonstrates skin test positivity to Candida antigen. Laboratory studies show that his serum IgG is 110 mg/dL. His total WBC count is 7650/microliter with differential count of 65 segs, 4 bands, 22 lymphs, and 9 monos. Which of the following immunologic disorders best explains these findings?
Failure of B cell maturation into plasma cells