Cellular Immune Responses to Cytomegalovirus in Renal Transplant Recipients

Abstract

Control of CMV replication depends primarily on anti-CMV T lymphocyte activity. However, the functional T-cell responses to CMV in immunosuppressed solid organ transplant recipients are not well understood. In this study we employed cytokine flowcytometry (CFC) using pooled CMV peptides and viral lysates to detect CMV-specific T-cell responses in 17 healthy controls, 33 stable renal transplant recipients (Tx recipients) and 6 transplant recipients with active CMV infection (CMV(+)). We found that pooled peptides and lysates provide optimal detection of IFNc production in anti-CMV CD8 + and CD4 + T cells, respectively. In both healthy controls and Tx recipients, CMV-specific T-cell levels strongly correlated with serostatus. Seropositive Tx recipients have significantly higher levels of CMV-specific CD8 + T-cell responses compared to healthy controls, which may signify an effort to control enhanced viral replication in immunosuppressed Tx recipients. In some individuals, absence of anti-CMV T-cell response may correlate with lack of viral clearance by ganciclovir therapy, even when CMV isolates are not ganciclovir resistant. Thus, monitoring cellular immunity with CFC along with viral load by PCR merits further exploration for identification of patients at the risk of developing CMV disease, tailoring prophylactic and therapeutic decisions and preventing complications.

Persistent Cytomegalovirus-Specific Memory Responses in the Lung Allograft and Blood following Primary Infection in Lung Transplant Recipients

“…These results are consistent with previous reports showing pp65 and IE1 to be the immunodominant target Ags for peripheral blood CTL in normal CMV-seropositive individuals and seropositive renal transplant recipients (22)(23)(24)(25), although we acknowledge that these CMV-specific T cell responses may underestimate the total cellular response, because recent evidence indicates a broader recognition of other CMV Ags (26 -28 ϩ T cells (CFSE low gated population) were assessed on day 6 following stimulation with CMV lysate (2.5 g/ml) for effector functions using allophycocyanin-labeled anti-IFN-␥, allophycocyanin-labeled anti-TNF-␣, and PE-labeled antigranzyme B, with brefeldin A (10 g/ml) added to cultures for the final 4 h. Also shown are allophycocyanin-labeled and PE-labeled isotype control Ab intracellular staining plots, gating on day 6, CFSE low , CD4…”

Immunobiology of Human Cytomegalovirus: from Bench to Bedside

“…A similar importance for CD8 ϩ T-cell immunity has been shown in the SOT setting. Analyses of virus-specific T-cell responses in renal transplant recipients demonstrated the presence of dominant CD8 ϩ T-cell responses that may limit viremia and protect against HCMV disease (209,213,238). In lung transplant recipients, the acquisition of HCMV-specific CD8 ϩ T-cell immunity, in addition to CD4 ϩ T-cell immunity, was associated with both freedom from HCMV disease and the preservation of allograft function compared with those who failed to develop HCMV immunity (240).…”

CMV: Prevention, Diagnosis and Therapy

“…Immuknow R , (Cylex, Colombia, MD, USA) which is not specific for CMV). Most studies that have analyzed CMV-specific T-cell responses have used intracellular cytokine staining for IFN-c using flow cytometry (available primarily in research settings) to demonstrate that low levels of CMV-specific cellular immunity predict an increased risk of CMV disease (46-48) and inability to clear viremia (46,49,50 …”