RELATIONSHIP OF OKT3 SENSITIZATION AND VASCULAR REJECTION IN CARDIAC TRANSPLANT PATIENTS RECEIVING OKT3 REJECTION PROPHYLAXIS

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Abstract
We prospectively and serially monitored plasma levels of OKT3 in 20 patients who were receiving 14− or 21-day rejection prophylaxis with OKT3. We retrospectively compared plasma OKT3 levels with biopsy scores assessed by light microscopy and immunofluorescence, clinical findings, human antimouse antibody (HAMA) production assessed by a blocking assay and by ELISA, and circulating immune complex levels assessed by a flow cytometric Raji cell assay. Using these methods, we evaluated the relationship of OKT3 sensitization, a humorally mediated immune response, to the development of vascular rejection in these patients. We found that 6 of 20 patients had declines in plasma OKT3 levels to less than 50% of their steady-state value before the conclusion of therapy (OKT3 consumption). This fall in plasma OKT3 preceded a significant rise in the CD 3 lymphocyte level by up to 3 days. All 6 patients showed HAMA production by either blocking or ELISA assay (P=P=P=P=<0.01). Prospective monitoring of patients treated with OKT3 by serial plasma levels and by biopsy immunofluorescence will identify patients at risk for these types of humoral rejection.