Abnormal B cell response to T cell-independent polyclonal B cell activators in haemophilia A.

In addition to T cell abnormalities, patients with haemophilia A show a separate B cell dysfunction. Characteristic are elevated spontaneous IgG (not IgM) levels in the patient's sera and in the culture supernatants of peripheral blood mononuclear cells. It is also observed that these cells fail to show a differentiation response to T cell-independent B cell activators. The B cell dysfunction correlates with the amount of factor VIII concentrates given prophylactically to patients with severe haemophilia. In contrast to the acquired immune deficiency syndrome (AIDS), the proliferation response to B cell mitogens is not affected.