High Monocyte Count Associated with Human Cytomegalovirus Replication In Vivo and Glucocorticoid Therapy May Be a Hallmark of Disease

Abstract

Cytomegalovirus (CMV) syndrome and infectious disease are defined as pathogen detection with appropriate clinical symptoms, but there are not pathognomonic signs of CMV disease. Although the prodrome of acute minor viral infections leukopenia (lymphopenia and neutropenia) is noted with onset of fever, followed by monocytosis, the role of monocytosis in CMV disease has not been described. Furthermore, under influence of corticosteroid therapy, CMV reactivation and monocytosis are described, but without a strict relationship with steroids dose. In the study, the monocyte level was investigated during the CMV infectious process. Regrettably, a non-selected group of 160 patients with high CMV viremia showed high dispersion of monocyte level and comparable with the median value for healthy subjects. Therefore, we investigated monocyte level in CMV-infected patients in relation to the logarithmic phase of the infectious process. Samples from patients with active CMV replication (exponential growth of CMV viremia) were tested. Significant monocytosis (above 1200/µL) during the logarithmic phase of CMV infection (with exponent between 3.23 and 5.77) was observed. Increased count and percentage of monocytes correlated with viral replication in several clinical situations except when there was a rapid recovery without relapse. Furthermore, glucocorticoids equivalent to 10 and 20 mg of dexamethasone during a 2-3-week period caused monocytosis-significant increase (to 1604 and 2214/µL, respectively). Conclusion: In light of the logarithmic increase of viral load, high monocytosis is a hallmark of CMV replication. In the COVID-19 era, presence of high virus level, especially part of virome (CMV) in the molecular technique, is not sufficient for the definition of either proven or probable CMV replication at any site. These preliminary observations merit additional studies to establish whether this clinical response is mediated by monocyte production or by decrease of differentiation to macrophages.

Keywords: CD14; clinical model/translational medicine; cytomegalovirus (CMV) kinetics; definitions of cytomegalovirus disease; homogeneous sample of subjects logarithmic phase of infection; innate immune response; monocytes characteristics and analysis; monocytosis; mononucleosis; virome; virus replication.

Figure 1

Regression and relationship between monocyte level (assessed with two methods) and CMV viremia—presented on vertical axis in logarithmic scale. Monocyte (hematology autoanalyzer), CD14+ cells (flow cytometry) counts are expressed on y axis.

Figure 2

Box and whisker plot for the monocyte level in patients with CMV infection in exponential phase of infectious process; * p < 0.05; ** p < 0.01.

Figure 3

Regression and relationship between monocyte count obtained in manual reference method (x axis) and two flow methods: (1) hematology analyzers, (2) cytometry with CD45vsSSC gating, or (3) CD14++ cells presented on y axis.

Figure 4

Relationship between CMV-DNA and monocyte count. Monocyte level and CMV copy numbers on 10⁵ nucleated cells of the whole blood (as the box) were expressed on the right and left axis, respectively.] According to the guidelines and diagnostic chain (see section Material and Methods), the CMV monitoring was carried out once a week. The course of CMV disease is presented in the timeline (weekly results are shown on the x-axis) until viremia withdrawal or fatal outcome. Exponential function of viremia with various bases (b) that are a positive real number higher than 1 and whole copy CMV number as a values of function f(x) = bx, when b > 1; x > 0. Representative patient plots of each group are shown in 3 clinical situations and outcomes: (A) symptomatic infection with rapid latency, exponent x = 4.77. (B) oligosymptomatic infection with rapid relapse with intensive symptoms of CMV mononucleosis and good outcome x = 4.52. (C) symptomatic primary infection with temporary viremia disappearance, prolonged intensive mononucleosis and relapse with fatal outcome. The exponential growth of viremia was the highest x = 5.77.

Figure 4

Relationship between CMV-DNA and monocyte count. Monocyte level and CMV copy numbers on 10⁵ nucleated cells of the whole blood (as the box) were expressed on the right and left axis, respectively.] According to the guidelines and diagnostic chain (see section Material and Methods), the CMV monitoring was carried out once a week. The course of CMV disease is presented in the timeline (weekly results are shown on the x-axis) until viremia withdrawal or fatal outcome. Exponential function of viremia with various bases (b) that are a positive real number higher than 1 and whole copy CMV number as a values of function f(x) = bx, when b > 1; x > 0. Representative patient plots of each group are shown in 3 clinical situations and outcomes: (A) symptomatic infection with rapid latency, exponent x = 4.77. (B) oligosymptomatic infection with rapid relapse with intensive symptoms of CMV mononucleosis and good outcome x = 4.52. (C) symptomatic primary infection with temporary viremia disappearance, prolonged intensive mononucleosis and relapse with fatal outcome. The exponential growth of viremia was the highest x = 5.77.

Figure 5

Various monocyte levels (hematology autoanalyzer) under the influence of ongoing glucocorticoid therapy. The dose of steroids was presented as an equivalent dose of dexamethasone that forms a geometric sequence (arⁿ) with common ratio r = 2 and start term a = 5 (exponential growth). For comparison, the subgroups within included patients (see Material and Methods), monocytosis was presented in included patients (also anti-CMV+ and immunodeficient) that had never been treated with steroids (right bar). The interquartile range (IQR) was about 1.5-fold higher for 5 and 10 mg of dexamethasone than 0 and 20 mg.