Cut-off value for absolute lymphocytes as an alternative for the immunophenotypic analysis of CD3+ T cells in the monitoring of immunosuppressive therapy with thymoglobulin.

Introduction: Immunosuppression of T lymphocytes is required for preventing acute rejection after transplantation and for the treatment of chronic autoimmune and inflammatory diseases. The laboratory monitoring for this therapy is the measurement of T cells by immunophenotyping, aiming the target value of less than 20 cells per µL.

Objective: To establish a cut-off point for the total number of lymphocytes in the automated blood cell count that reflects less than twenty T cells µL by immunophenotyping.

Methods: We studied and evaluated 242 kidney transplant patients that had results of automated blood cell count and quantification of T cells by immunophenotyping technique. The patients were divided into two groups, depending on the T lymphocyte immunophenotyping rates established by lower and higher than 20 cells per µL. After, we evaluated the cut-off point for lymphocytes in the blood cell count with a specificity of 100% to exclude patients with high levels of T lymphocytes.

Results: We found that the cut-off point of 70 lymphocytes per µL obtained by automated blood cell count showed 100% of specificity to exclude patients with T-cell counts higher than 20 cells per µL by immunophenotyping.

Conclusion: The results found in this study may be helpful to monitor the immunosuppressive therapy in kidney transplant patients in places where a flow cytometer is not available, or when this equipment is not present in the full routine.