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RECOVERY OF T CELL MEMORY CELLS IN LUNG TRANSPLANT RECIPIENTS TREATED WITH T CELL DEPLETION THERAPIES.
Kathy Spichty, BS, Kevin McDade, BS, Husain Shahid, MD, Carol Bentlejewski, BS, Alin Girnita, MD, Diana Zaldonis, RN, Judy Britz, PhD, Richard Kowalski, PhD, Julie Woodcock, BS, Kenneth McCurry, MD and Adriana Zeevi, PhD. Pittsburgh PA, USA, UPMC, Pathology; Surgery and Baltimore MD, Cylex Inc..

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We measured the recovery of T cell responses to ConA, CMV and EBV in 59 lung transplant (LTx) recipients treated with T cell depletion and 11 controls. A Cylex ImmuKnow-CD3 assay was used to assess T cell immunity. Whole blood is co-incubated with anti-CD3 coated magnetic beads and antigen. T cell activity measured within 24 hr is detected by ATP production.
LTx recipients were pre-treated with Thymoglobulin (Thy - 36) or Campath (23). The ConA response post-Tx in the Thy group was lower in LTx recipients as compared to controls, up to 10 months post-Tx (control ATP 360±132 ng/ml vs. LTx ATP<150 ng/ml). The ConA response recovered at 10 months. In 6 CMV negative recipients who received a CMV neg. donor (R-D-) the mean ATP was <10 ng/ml. During the first 6 months post-Tx all R-/D+ patients (8 samples) had ATP level <10 ng/ml. In contrast, 5/7 of the CMV seropositive recipients (R+) had ATP levels >10 ng/ml. After 7 months post –Tx, the CMV-specific memory responses seem to recover in both groups (10/11 R-/D+ and 17/18 R+ had ATP >10ng/ml). For EBV-specific T cell memory, results greater than 15 ng/ml ATP were considered positive. Most of the recipients were EBV positive and the responses in the first 6 months post-Tx were suppressed (8/19 expressing levels <15 ng/ml). Following 6 months post-Tx, only 4/44 samples exhibited levels of ATP <15 ng/ml. Similar results were seen with Campath treated patients.
Conclusion: The CD3 assay may be used as adjunct to the assessment of viral load to monitor T cell immunity. This would allow for adjusting immunosuppression in Tx recipients.