B cell defects. 1. Bruton (X-linked), recurrent pyogenic, males, 6 months. GIARDIA. No plasma cells in GI biopsies. Very low serum IgG. Normal immunity to viral and fungal, increased risk of lymphomas. Atk gene (Tyrosine kinase). 2. CVID low overall serum Ig of every class and some T cell issues too. RESPIRATORY TRACT, Giardia, bronchiectasis. Normal number of B cells but cannot differentiate into plasma cells. 3. Selective IgA. 4. Job (hyper E) and exquisite sensitivity to Staph with eos and eczema.