Assessment of the risk for broad sensitization by blood transfusions.

The risk factors associated with the production of lymphocyte antibodies were studied by evaluating the conditions of sensitization in 73 renal failure patients and by searching for lymphocyte antibodies by flow cytometry before the induction of overt sensitization by blood transfusions. In 14 patients the lymphocytotoxic antibodies were not broadly reactive and became undetectable within 5 months. These patients were mostly first transplant candidates who received transfusions prior to the rise of panel antibody reactivity. The remaining 59 patients developed broadly reactive antibodies that persisted for longer than 5 months, regardless of whether or not they were given subsequent blood transfusions. This group was made up almost exclusively of multiparous women or patients who had previously lost a kidney graft. There were 13 patients having no lymphocytotoxic antibodies who developed broad sensitization after blood transfusions. These patients were also multiparous women or previously transplanted patients, suggesting that previous exposure to alloantigens by transplants or pregnancies appeared to be a precondition for blood transfusions to induce broad sensitization. This was confirmed by detecting lymphocyte antibodies by flow cytometry in the pretransfusion serum of 9 of the 13 patients. In contrast, patients who did not make antibodies after transfusions, or those who developed temporary responses, did not have lymphocyte antibodies in their pretransfusion specimens. These findings suggest that patients with low levels of lymphocyte antibodies, not detectable by standard cytotoxicity, are at high risk of developing broadly reactive cytotoxic antibodies after blood transfusions.