Early onset agammaglobulinaemia with monoclonal IgG production.

Two patients are described with X-linked agammaglobulinaemia (XLA). After a period of gammaglobulin infusions endogenous IgG production appeared to resume and gammaglobulin therapy was gradually stopped. However, bacterial respiratory tract infections recurred. Immunological evaluation showed normal levels of serum IgG with mono/oligoclonal IgG m-bands, while B lymphocytes and plasma cells were absent from the peripheral blood and bone marrow. Endogenous IgG was synthesized in plasma cells in the submucosa of the gastrointestinal tract. Renewed high doses of exogenous gammaglobulin led to the reduction of infections and the disappearance of mono/oligoclonal m-bands in the serum. We suggest that as a rare complication of XLA some pre-B-cells may escape the blockade to B-cell maturation and produce mono/oligoclonal IgG, possibly due to chronic infectious stimulation.