Dose titration during anti-thymocyte globulin therapy: monitoring by CD3 count or total lymphocyte count?

Single-dose antithymocyte globulin in standard immunological risk kidney transplant recipients: efficacy and kinetics of peripheral blood CD3+ T lymphocyte modulation

BACKGROUND

Polyclonal anti-T cell antibodies (ATG or thymoglobulin®) are used as induction therapy in kidney transplant recipients. This study evaluates the safety, efficacy, and CD3+ T lymphocyte modulation of two ATG regimens.

METHODS

The trial included two cohorts of kidney transplant recipients that were followed for one year. The study group, including standard immunological risk recipients, received one 3 mg/kg dose of ATG. The comparator group, including standard and high immunological risk kidney transplant recipients, received a fractionated dose regimen (up to four 1.5 mg/kg doses). Patient and graft outcomes and the kinetics of CD3+ T lymphocyte modulation in the peripheral blood were evaluated.

RESULTS

One hundred kidney transplant recipients were included in each group. The one-year incidence of treated acute rejection, and patient and graft survival did not differ between groups. Bacterial infections were significantly more frequent in fractionated-dose group patients (66% versus 5%; P = 0.0001). At one-year follow-up, there was no difference in the incidence of cytomegalovirus infection (P = 0.152) or malignancies (P = 0.312). CD3+ T lymphocyte immunomodulation in the single-dose group was more effective in the first two days after transplantation. After the third post-transplant day, CD3+ T lymphocyte modulation was more efficient in the fractionated dose group.

CONCLUSION

Both regimens resulted in low rejection rates and equivalent survival. The single and reduced dose regimen protects from the occurrence of bacterial infections. CD3+ T lymphocyte modulation occurred with different kinetics, although it did not result in distinct outcomes.

Polyclonal anti T-lymphocyte antibody therapy monitoring in kidney transplant recipients: comparison of CD3+ T cell and total lymphocyte counts

Objective:

To investigate the correlation between total lymphocyte and CD3⁺ T cell counts in peripheral blood in renal transplant patients treated with anti-thymocyte globulin, and discuss related outcomes.

Methods:

A single-center, retrospective study involving 226 patients submitted to kidney transplant between 2008 and 2013, and treated with anti-thymocyte globulin for induction or treatment of cellular rejection. Doses were adjusted according to CD3⁺ T cell or total lymphocyte counts in peripheral blood.

Results:

A total of 664 paired samples were analyzed. The Spearman's correlation coefficient was 0.416 (p<0.001) for all samples combined; the overall Kappa coefficient was 0.267 (p<0.001). Diagnostic parameters estimated based on total lymphocyte counts were also calculated using the number of CD3⁺ T cells (gold standard), with a cut off of >20 cells/mm³.

Conclusion:

Total lymphocyte and CD3⁺ T cell counts in peripheral blood are not equivalent monitoring strategies in anti-thymocyte globulin therapy.

Drug-Induced Hematological Cytopenia in Kidney Transplantation and the Challenges It Poses for Kidney Transplant Physicians

Drug-induced hematological cytopenia is common in kidney transplantation. Various cytopenia including leucopenia (neutropenia), thrombocytopenia, and anemia can occur in kidney transplant recipients. Persistent severe leucopenia or neutropenia can lead to opportunistic infections of various etiologies. On the contrary, reducing or stopping immunosuppressive medications in these events can provoke a rejection. Transplant clinicians are often faced with the delicate dilemma of balancing cytopenia and rejection from adjustments of immunosuppressive regimen. Differentials of drug-induced cytopenia are wide. Identification of culprit medication and subsequent modification is also challenging. In this review, we will discuss individual drug implicated in causing cytopenia and correlate it with corresponding literature evidence.

Flow cytometry in hematological disorders

Flow cytometry with its rapidly increasing applications is being used essentially in all fields of diagnostic medicine. In hematological disorders it is most commonly used in diagnosis, characterization, prognostication and even selecting target therapy of acute leukemia and to some extent lymphomas. It is increasingly finding place in other fields of hematology i.e., non-malignant disorders of all blood cell types including RBCs and platelets along with leukocytes. In this review the authors have discussed some of these applications with an emphasis on disorders specific to pediatric patients.

A CD3+ count-based thymoglobulin induction regimen permits delayed introduction of calcineurin inhibitors in kidney transplantation

BACKGROUND

Withholding calcineurin inhibitors (CNIs) can be considered when graft function is inadequate following kidney transplantation (KT). Thymoglobulin (rATG) can be used to prevent acute rejection while CNIs are being withheld. Here, we report our results of a novel CNI-sparing induction protocol, which utilizes a CD3+ cell count-based rATG treatment regimen when delayed graft function (DGF) develops in the immediate postoperative period.

METHODS

In a cohort of 153 consecutive deceased-donor KT recipients, all received a single intraoperative dose of basiliximab; 84 subsequently developed DGF and therefore received rATG (rATG+ group), while 69 demonstrated immediate graft function and received CNIs (rATG- group).

RESULTS

In the rATG+ group, mean duration of therapy was 8.5±6.0 d, permitting CNI initiation to be delayed until postoperative day 10.3±6.2. Cumulative dose of rATG was only 5.1±4.5 mg/kg while targeting CD3+ counts of ≤30 cells/mm3. CD3+ counts were reduced to a mean of 16.7±17.0 cells/mm3 during therapy. At one yr, patient and graft survival rates were 97.6% and 92.9%, respectively, while the frequency of infections and malignancies were not significantly increased compared to the rATG- group.

CONCLUSION

A unique induction regimen successfully delayed CNI initiation by using modest doses of rATG to deplete CD3+ cells, while yielding excellent long-term graft outcome without increased risk of infection or malignancy.

Low dose antithymocyte globulins in renal transplantation: daily versus intermittent administration based on T-cell monitoring

BACKGROUND

Despite the long history of use of antithymocyte globulins (ATG) in renal transplantation, ideal doses and duration of ATG administration based on the monitoring of T lymphocytes have yet to be defined.

METHODS

Two immunosuppressive regimens based on low-dose rabbit ATG (Thymoglobuline; Imtix-Sang-stat, Lyon, France) were assessed during the first year after transplantation: daily ATG (DATG; n=23) where 50 mg of ATG was given every day and intermittent ATG (IATG; n=16) where similar doses of ATG were given for the first 3 days and then intermittently only if CD3+ T lymphocytes (measured by flow cytometry) were > 10/mm3. Both groups received steroids, azathioprine, and cyclosporine.

RESULTS

ATG-induced depletion was similar for peripheral blood lymphocytes and T cells in both groups: it began at day 1 after transplantation, was submaximal at day 3, and reached maximum intensity between days 6 and 8, from which time cell counts progressively increased. However, T-cell depletion was still present at day 20. The total ATG dose per patient (381.5+/-121 vs. 564+/-135 mg/patient) and the mean cumulative daily dose of ATG (0.60+/-0.17 vs. 0.80+/-0.14 mg/kg/day) were significantly lower in the IATG group (P=0.0001 and 0.0006, respectively). The overlap of ATG and cyclosporine treatment was 6.7+/-3 vs. 7.4+/-4.3 days (P=NS), and the mean duration of ATG therapy was 11.3+/-3.2 vs. 11.6+/-2.7 days in the IATG and DATG groups, respectively (P=NS). ATG was given in an average of one dose every 1.6 days in the IATG group compared with one dose daily in the DATG group (P=7 x 10(-7)). There was no significant difference in renal graft function, the number of acute graft rejections, or ATG-related side effects and complications. Despite the daily immunological follow-up, there was a net saving of $760/patient in the cost of treatment in the IATG group.

CONCLUSION

IATG had the advantage of a reduction in the dose of ATG and in the cost of treatment, while offering similar T-cell depletion and effective immunosuppression. This approach could be proposed as an induction protocol, particularly for patients with poor graft function in whom cyclosporine introduction has to be delayed or those with increased risk of cytomegalovirus infections or secondary malignancies.