Immunological dysfunction in paroxysmal nocturnal haemoglobinuria

In five patients with paroxysmal nocturnal haemoglobinuria (PNH) immune capacity was tested. We found impaired in-vitro lymphocyte proliferation after stimulation with allogenic lymphocytes and concanavalin A (con A) in different concentrations. This suggests a disturbed T-cell immunity in these patients, although the number of T cells were normal. As the response to phytohaemagglutin (PHA) stimulation was adequate in most patients, it is presumed that a part of the T-cell population remains normal, as is also suggested by a normal in-vivo response to dinitrochlorobenzene (DNCB). Normal immunoglobulin (Ig) levels and normal anti Helix pomatia haemocyanin (HPH) antibody response were found in most patients. Some patients showed a very low response to pokeweed mitogen (PWM), suggesting some disturbance in the B cell capacity. The decreased number of B cells, found in all patients may also be attributed to this dysfunction. Exposure to inulin enhances the in-vitro effect in lymphocytes of patients with PNH. This indicates functional damage in a population of lymphocytes, possibly originating from an abnormal cell clone with the PNH characteristics. It is therefore suggested that the immunological disturbances could be caused by the primary bone marrow disease.