Lack of cytomegalovirus (CMV)-specific cell-mediated immune response using QuantiFERON-CMV assay in CMV-seropositive healthy volunteers: fact not artifact

Abstract

The QuantiFERON-CMV (QF) assay measures cell-mediated immunity against cytomegalovirus (CMV-CMI), which is particularly useful in individuals susceptible to CMV infection such as transplant patients. A positive QF result identifies patients that are better protected against CMV infection. However, the significance of a negative QF result in CMV-seropositive individuals needs to be clarified. CMV-CMI was analyzed in healthy subjects using the QF assay, and, in parallel, the Flow-cytometric Assay of Specific Cell-mediated Immune response in Activated whole blood (FASCIA). FASCIA assay measures T-cell proliferation using CMV lysate as stimulus whereas QF assay use a mix of peptides. A total of 93 healthy volunteers were enrolled, and 13/71 CMV-seropositive individuals (18.3%) showed humoral/ cellular discordance using QF assay (CMV+ QF−). Interestingly, with FASCIA assay CD4+ and CD8+ T-cell proliferations were lower in CMV+ QF− than in CMV+ QF+ individuals. Furthermore, CMV+ QF− volunteers had a lower level of anti-CMV IgG than CMV+ QF+ subjects. Discordant CMV+ QF− volunteers can be defined as low responder individuals since they show lower CMV-specific humoral and cellular immune responses in comparison to CMV+ QF+ individuals. Immune discordance shows the high heterogeneity of immunity to CMV in healthy subjects.In the last years, a variety of assays have been developed to measure cell-mediated immunity against cytomegalovirus (CMV-CMI), where the basic principle is the CMV-specific stimulation of T cells for 6-24 hours in cell culture 1,2 . These techniques have been shown to be particularly useful in individuals such as transplant patients who are susceptible to CMV infection, since they identify who is better protected against CMV infection after transplantation, as has been reported in international guidelines on the management of CMV in solid organ or stem cell transplantation 3,4 . Specifically, the detection of CMV-CMI at pretransplant or posttransplant using QuantiFERON-CMV (QF), ELISpot or intracellular cytokine staining has been associated with a lower risk of CMV infection, not only in observational studies 5-9 .Although most individuals show an agreement between CMV-serostatus and CMV-CMI, some of them have a discordance. Therefore, there are CMV-seropositive individuals without CMV-CMI, as well as CMV-seronegative individuals with protective CMV-CMI. Discordant individuals have been reported in both transplant patients and healthy virus carriers 8-12 .The QuantiFERON-CMV is an in vitro assay that measures CMV-CMI by quantifying IFNG released by CD8+ T cells after stimulation with a pool of HLA-restricted CMV peptides 13 . In some observational studies carried out in our group in solid organ transplant patients we found that 20-25% of CMV-seropositive transplant open Scientific RepoRtS | (2020) 10:7194 | https://doi.org/10.1038/s41598-020-64133-x www.nature.com/scientificreports www.nature.com/scientificreports/ candidates lacked CMV-CMI response using the QF assay, and they showed a higher risk of p...

Laboratory diagnostic testing for cytomegalovirus infection in solid organ transplant patients

“…About 60% of pretransplant CMV-seropositive recipients were negative for CMV-QF [ 70 ]. A recent study performed CMV-CMI in healthy individuals and found 18.3% (13/71) revealed humoral/cellular discordance, showing CMV-seropositivity with CMV-QF negativity [ 71 ]. Individuals with inconsistent results had lower levels of CD4+ and CD8+ T cell proliferation in response to CMV lysate stimulation and expressed a lower level of anti-CMV IgG.…”

“…Individuals with inconsistent results had lower levels of CD4+ and CD8+ T cell proliferation in response to CMV lysate stimulation and expressed a lower level of anti-CMV IgG. This suggests that immune response to CMV was highly heterogeneous in healthy subjects [ 71 ]. In addition, CMV-QF only measures the CMV-specific CD8+ T cell response.…”

Characterization of NKG2-A/-C, Kir and CD57 on NK Cells Stimulated with pp65 and IE-1 Antigens in Patients Awaiting Lung Transplant

“…The study by Zhang et al raises the possibility that sFasL may contribute to host defenses by aiding the resolution of inflammatory exudate, independently of any effect on viral replication [33]. The lack of CMV-specific cell-mediated immune response detected by QuantiFERON-CMV assay in CMV-seropositive individuals was already reported by Valle-Arroyo et al [29] CMV infection can change the expression of NK cell membrane receptors, promoting the progressive expansion and persistence of mature phenotypes characterized by CD56 dim , KIR expression and NKG2A neg /CD57 pos . Our results are intriguing, because double-positive cells are NK cell subsets characterized by the double expression of NKG2A and KIR.…”

“…Let us also highlight a possible bias of our study due to QF-CMV. This in vitro assay measures CMV cell-mediated immunity by quantifying INFγ released by cells after stimulation with a pool of HLA-restricted CMV peptides [ 29 ]. Many limits of this method have been reported.…”

A Prospective Study of Cytomegalovirus-Specific Cell-Mediated Immune Monitoring and Cytomegalovirus Infection in Patients With Active Systemic Lupus Erythematosus Receiving Immunosuppressants

“…These data could identify individuals at higher risk of infection (eg, patients who have positive CMV IgG but are QF-nonreactive). The high heterogeneity of CMV-specific immunity has also been demonstrated in immunocompetent individuals [ 27 ].…”