Polymorphonuclear cells are not sites of persistence of human cytomegalovirus in healthy individuals

Abstract

Polymorphonuclear leukocytes (PMNL) have been shown to harbour human cytomegalovirus (HCMV) in viraemic patients, but to date PMNL of asymptomatic healthy subjects have not been examined directly to determine whether this is a normal site of HCMV persistence. Using the polymerase chain reaction (PCR), paired DNA samples prepared from adherent peripheral blood mononuclear cells (PBMC), which are known to be a site of persistence of HCMV, and PMNL of 10 healthy adults were analysed. All of seven individuals who were HCMV seropositive, and one of three who were seronegative gave a reproducible signal for HCMV DNA in their adherent PBMC, whereas none of the paired PMNL DNA samples gave a positive result. The remaining two seronegative subjects showed no HCMV DNA in either the PBMC or PMNL samples. In every case where PCR for HCMV was negative, PCR amplification of a control human gene was used to show there was no inability to amplify the DNA. We conclude that within the leukocyte population of normal asymptomatic HCMV carders, PMNL do not appear to harbour persistent HCMV whereas adherent PBMC in the same subjects are a site of persistence.We and others have previously used the polymerase chain reaction (PCR) to demonstrate the presence of human cytomegalovirus (HCMV) in leukocytes of seropositive and some seronegative healthy carriers (Taylor-Wiedeman et al., 1991; Stainer et al., 1989). In these normal subjects, peripheral blood monocytes (PBMC) were the principal site of persistence (TaylorWiedeman et al., 1991). However, only PBMC were studied and analysis of polymorphonuclear leukocytes (PMNL) from healthy carriers was not addressed.Detection of HCMV in the PMNL fraction of peripheral blood has been reported in patients infected with human immunodeficiency virus (HIV), other immunocompromised patients and immunocompetent patients acutely ill with HCMV (Saltzman et al., 1988;Dankner et al., 1990;Fiala et al., 1975;Rinaldo et al., 1977; Revello et al., 1992;Gerna et al., 1991). Consequently, we were interested in determining whether the granulocyte might also represent a normal site of persistence which would be consistent with the clinical observations that HCMV is present in PMNL of viraemic patients. To determine this, DNA from PMNL cells and adherent PBMC from the same blood sample for each of 10 healthy subjects was prepared and examined by PCR. In this report we show that PMNL are not a source of persistent virus in the leukocyte population of normal asymptomatic HCMV carriers.Subjects were all healthy adult volunteers whose serological status was determined using a competitive ELISA (CompEnz-CMV, Northumbria Biologicals). One subject's serum gave a negative result in ELISA but DNA from adherent PBMC was PCR-positive. A second serum sample, examined 2 months later using an HCMV latex agglutination assay (Becton Dickinson), showed the individual to have remained seronegative. Lymphoprep (Nycomed) gradient separations yielded PBMC, banding at the plasma interface, and PMNLenriched fractions lying at the top ...

Fibroblasts, epithelial cells, endothelial cells and smooth muscle cells are major targets of human cytomegalovirus infection in lung and gastrointestinal tissues

“…In contrast, the lack of morphological alterations as well as the absence of any detectable early and late viral antigens in infected PMNL indicates that these cells are only abortively infected. In agreement with this are analyses on PMNL from peripheral blood, in which no synthesis of late viral antigen could be demonstrated (Taylor-Wiedeman et al, 1993;Grefte et al, 1992). Taken together, compared with the conflicting data from earlier in vivo studies based on histopathology alone, the immunohistochemical double staining analysis corresponded much better with the replication of HCMV in cell culture systems.…”

Latency, chromatin remodeling, and reactivation of human cytomegalovirus in the dendritic cells of healthy carriers

“…Accumulating evidence has shown that HCMV is carried latently in mononuclear cells of the myeloid lineage during lifelong latency in naturally infected individuals (5)(6)(7)(8). Differentiation of monocytes to macrophages in vitro is reported to induce immediate-early (IE) lytic gene expression from latent virus (9), and groups have intermittently reported that infectious virus can be recovered after differentiation of monocytes to macrophages through explant culture (10) and, more recently, by allogeneic T cell stimulation (11), suggesting that reactivation of latent virus is associated with both the differentiation and activation state of myeloid cells.…”

Human Cytomegalovirus Inhibits Differentiation of Monocytes into Dendritic Cells with the Consequence of Depressed Immunological Functions

“…Interestingly, monocytes are primary HCMV target cells in vivo and are responsible for dissemination of the virus throughout the body during the latent, acute, and late phases of infection. Thus, the monocyte represents a key cell type in the pathogenesis of HCMV infection, since this cell type represents an important cellular reservoir for latent virus (45,50,51). A number of studies have shown that HCMV infection in monocytes is nonpermissive (11,34) and that cellular differentiation is a prerequisite for HCMV replication (13,18,42,46,52).…”