Infection of endothelial cells with an endothelial cell-tropic clinical isolate of cytomegalovirus (CMV), C1FE, induced enhanced production of the neutrophil chemoattractant C-X-C chemokines interleukin-8 and GROalpha. Infected endothelial cell supernatants induced neutrophil chemotaxis in a transendothelial migration assay. Neutrophils acquired the CMV structural protein pp65 following either coculture with infected endothelial cells or transmigration through infected endothelium. The lack of CMV p72 expression in the neutrophils indicated that viral replication had not occurred in these cells. Of importance, neutrophils acquired infectious CMV during transmigration across infected endothelium and were subsequently able to transmit infectious virus to fibroblasts. Thus, CMV-infected endothelial cells can recruit neutrophils by the secretion of C-X-C chemokines and can transmit the virus to them by direct cell-to-cell contact and during neutrophil transendothelial migration, suggesting that the neutrophil-endothelial cell interaction plays an important role in virus dissemination in vivo.
A human cytomegalovirus (HCMV) glycoprotein B (gpUL55) DNA vaccine has been evaluated in BALB/c mice. Intramuscular immunization of these mice with pRc/CMV2-gB resulted in the generation of high levels of gpUL55-specific antibody (geometric mean titer [GMT] 1:8900) and neutralizing antibody (GMT 1:74) after 2 booster doses given 5 and 10 weeks after primary inoculation. Emulsifying the construct with the aluminum phosphate gel adjuvant Adju-Phos before immunization enhanced gpUL55-specific antibody responses (GMT 1:17800, P = 0.04). Co-immunization with CpG oligodeoxynucleotides was shown to enhance levels of neutralizing antibodies generated by immunization of mice with a pRc/CMV2-gB/Adju-Phos emulsion (P = 0.04). The results provide a rationale for evaluating combinations of other HCMV proteins for incorporation into a multi-target DNA vaccine, and for the optimization of adjuvant usage, to elicit enhanced levels of neutralizing antibodies. 2003.
Introduction: Perforin (PF) expressing CD4+ T cells are expanded in B-CLL patients [1] and are able to induce PF-mediated apoptosis of autologous leukaemic cells in the presence of bispecific anti-CD3/CD19 antibodies [2]. However, the role of the expanded PF+CD4+ T population in B-CLL remains unclear. In this study we have examined possible involvement of this cell subset in immune responses to cytomegalovirus (CMV). Methods: Blood mononuclear cells from 11 CMV seropositive (SP) and 6 seronegative (SN) B-CLL patients were cultured for 4 and 18 hours in presence of Downe cell lysates containing CMV-antigen or cell lysates alone (control) and brefeldin and co-stimulated with anti-CD28 and anti-CD49 monoclonal antibodies. Anti-CMV response was assessed by flow cytometry as percentages of CD69+ and IFNγ+ cells in PF+ and PF- CD4+T cell populations. Results: CD4+ T cells from 9 of 11 SP patients showed a strong increase in percentages of IFNγ+ cells after 18h, but not 4h, in culture with CMV antigens, compared to the control lysates and SN patients (Table) and healthy age-matched SP subjects (1.78±0.45, p=0.012). In contrast, none of the 6 SN patients as well as 2 out of 11 SP patients responded to CMV by increased IFNγ expression. In responders IFNγ+ cells were proportionally distributed between PF+ and PF- CD4+ T cells. High levels of cell activation measured by CD69 expression, especially in PF+ population, were mainly due to the Downe cell lysate since expression was significantly lower in lysate free cell cultures (8.3±11.5%, p=0.0018 for SP B-CLL patients). Anti-CMV response was accompanied by a decrease in percentages of CD4+PF+ cells suggesting antigen-induced degranulation. Conclusion: PF+CD4+ T cells respond to CMV antigens suggesting an expansion of mature CMV specific cytotoxic CD4+ T cells in the majority of CMV seropositive B-CLL patients. IFN-γ and CD69 expression by CD4+PF+ and PF- T cells after 18h exposure to CMV+ and CMV- lysates in CMV seropositive and seronegative B-CLL patients CD4+ PF+ CD4+ PF-CD4+ SN SP SN SP SN SP IFN- γ, % CMV+lys 0.7±0.58 9.1±7.9 2.0±3.0 p=0.013 14.4±13.6 0.61±0.56 p=0.008 9.0±8.1 CMV−lys 0.26±0.34 0.9±1.7 p=0.007 1.1±1.7 3.9±6.9 p=0.029 0.24±0.27 1.46±2.55 p=0.013 CD69+cells, % CMV+lys 16.3±14.2 21.4±13.0 41.9±35.1 51.2±30.3 14.9±13.4 20.4±13.2 CMV−lys 14.4±12.8 9.7±7.8 28.6±34.8 39.8±33.0 13.8±12.1 12.9±15.0
Introduction: An expansion of CD4+ T cells expressing perforin (PF) has recently been described in B-CLL and we have previously demonstrated anti-cytomegalovirus (CMV) reactivity within this population (Walton et al; 2004; Blood [ASH annual meeting abstracts] 104:4787). Here we further characterise the anti-CMV response of CD4+PF+ T cells in B-CLL and investigate the role of CMV in CD4+PF+ T cell expansion. Methods: Peripheral blood mononuclear cells (PBMC’s) from 24 untreated B-CLL patients (17 CMV seropositive [SP], 7 CMV seronegative [SN]), 2 SP treated (Campath) patients and 12 healthy age-matched control individuals (8 SP, 4 SN) were fixed, permeabilised and stained with anti-CD4PerCP, anti-IFN-γ-APC and anti-PF-FITC monoclonal antibodies (mABs) (BD). PBMC were cultured for 18 hrs with DOWNE cell lysate (Dade Behring) containing CMV-antigen or lysate alone and with anti-CD28 and anti-CD49d mAbs (BD), in the presence of Brefeldin A (eBiosciences). In blocking experiments PBMC were pre-incubated with anti-HLA DR,DP,DQ mAb (BD) for 1 hour. The CMV specific response was assessed by flow cytometry (Dako Cyan, Summit software) as the percentage of IFN-γ+ cells in PF+ and PF− CD4+ T cell populations. Statistical analysis was performed using the Mann-Whitney U test and Spearman rank correlation. Results: The proportion of CD4+ T cells expressing PF directly ex vivo was significantly higher in SP B-CLL patients (17.5±18.6%) compared to SN patients (2.0±2.3%, p=0.019). In seropositive aged matched controls the percentage of CD4+ cells expressing perforin was positively correlated with the percentage of CMV-reactive CD4+ cells (r=0.976, p<0.01). In contrast, there was no significant correlation in the patient group. However, two patients with relatively large expansions of CD4+PF+ cells (37.7±3.39%) post-Campath treatment had high percentages of CMV-reactive CD4+ cells (10.93±0.62%) compared to SP B-CLL patients (1.34±1.19%) and SP controls (1.31±1.14%), implying Campath related CMV reactivation. The addition of anti-HLA-DR,DP,DQ mAb to patients’ PBMCs, prior to CMV stimulation, led to an 80% (from 3.26% to 0.79%) and 90% (from 3.9% to 0.45%) reduction in the proportion of antigen reactive CD4+ and CD4+PF+ cells respectively. Conclusions: A population of major histocompatibility complex (MHC) class II restricted, CMV reactive, CD4+PF+ T cells exists peripherally, in a large group of CMV SP B-CLL patients. Furthermore, CMV is associated with CD4+PF+ T cell expansion in patients and controls. Our data implies that high numbers of B-CLL cells inhibit anti-viral effector function, leading to increased viral activity and chronic antigenic exposure, potentially driving CD4+PF+ T cell expansion.
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