Lymphocytes from multi-transfused patients exhibit cytotoxicity against autologous cells

We previously demonstrated that multitransfused patients with severe aplastic anaemia (SAA) exhibit high numbers of alloreactive cytotoxic T lymphocyte precursors directed against their HLA identical siblings. In this study a group of patients who had received multiple blood transfusions for SAA, other haematological diseases or acute blood loss were tested for autocytotoxicity and the results compared with those of untransfused controls. These controls consisted of normal individuals, patients with chronic myeloid leukaemia (CML) or untransfused patients with SAA. There was a significantly higher degree of autocytotoxicity in multitransfused patients, than in the untransfused controls, including untransfused patients with SAA (P = 0.0001). These results suggest that blood transfusion is responsible for inducing autoreactivity. In one patient, in whom both alloreactive anti-non-MHC and autoreactive cytotoxic T lymphocytes (CTL) had been detected, it was demonstrated that there was no crossreactivity between the alloreactive and autoreactive CTL responses. Inhibition studies using monoclonal antibodies revealed the effector cells to be T lymphocytes and the restricting determinants to be both HLA class I and II molecules.