Assessment of the Immune Reconstitution by Cylex Immuknow™ Assay in Patients after Allogeneic Stem Cell Transplantation.

After engraftment of allogeneic stem cell transplantation (allo-SCT) patients are severely immuno-suppressed and are susceptible for recurrent opportunistic infections on one hand; on the other hand, particularly without immunosuppressive treatment over-activity of the graft can lead to uncontrolled acute or chronic graft-versus-host disease (GvHD); optimal immunological activity of the graft is necessary to control the underlying malignant disease and to prevent relapse. Therefore, accurate immune monitoring is crucial for the assessment and appropriate management of the immune-compromised patients after allo-SCT. Since October 2005 up to 6 consecutive blood samples were collected from 51 patients undergoing allo-SCT in Hadassah Medical Center following engraftment. Immune function was analyzed by Cylex Immuknow™ assay, an FDA approved immune cell function test for the assessment of cell-mediated immunity. ATP activity from magnetically separated and lysed CD4 lymphocytes is measured by light intensity, thereby reflecting the current immune function of the patient. From other clinical applications of this test, the following stratification of the immune response was established according to the following levels of ATP activity: Low (0–225 ng/mL), moderate (225–525 ng/mL) and high activity (>525 ng/mL) of immune response. Our preliminary results from allo-SCT patients are in keeping with their clinical course and the known stratification of the ATP level:

1. The gradual increase to moderate ATP levels over several months after allo-SCT are in keeping with normal immune reconstitution with an uneventful post transplant clinical course;

2. high ATP levels were observed in patients prior to the clinical presentation of acute GVHD;

3. low ATP levels were associated with recurrent infections and relapse.

Remarkably, there was no correlation with the recovery of the white cell count after allo-SCT. Our results with consecutive tests are the first study of Cylex Immuknow™ assay in patients after allo-SCT and are in keeping with other currently known clinical applications of this assay for other indications. Our preliminary observations indicate a promising contribution of Cylex Immuknow™ assay as a simple and fast monitoring technique for patients undergoing allo-SCT, which might also predict clinical complications. Our future follow-up studies aim to confirm these preliminary results in order to gain confidence in the assay’s clinical contribution as a possible standard test for patients after allo-SCT.