Differential effects of Cytomegalovirus carriage on the immune phenotype of middle-aged males and females

Abstract

The elderly population is more susceptible to infections as a result of an altered immune response, commonly referred to as immunosenescence. Cytomegalovirus (CMV)-infection associated changes in blood lymphocytes are known to impact this process, but the interaction with gender remains unclear. Therefore, we analysed the effects and interaction of gender and CMV on the absolute numbers of a comprehensive set of naive and memory T- and B-cell subsets in people between 50 and 65 years of age. Enumeration and characterisation of lymphocyte subsets by flow cytometry was performed on fresh whole blood samples from 255 middle-aged persons. CMV-IgG serostatus was determined by ELISA. Gender was a major factor affecting immune cell numbers. CMV infection was mainly associated with an expansion of late-differentiated T-cell subsets. CMV+ males carried lower numbers of total CD4+, CD4+ central memory (CM) and follicular helper T-cells than females and CMV- males. Moreover, CMV+ males had significantly lower numbers of regulatory T (Treg)-cells and memory B-cells than CMV+ females. We here demonstrate an interaction between the effects of CMV infection and gender on T- and B-cells in middle-aged individuals. These differential effects on adaptive immunity between males and females may have implications for vaccination strategies at middle-age.

Figure 1. Effect of CMV on the CD8 and CD4 T-cell lineages.

(a) Gating strategies for the CD8 T-cell subsets. A representative example is shown. (b) A cumulative schematic overview of the geometric mean values of absolute numbers of CD8 naive, CM, TemRO, and TemRA cells in CMV− and CMV+ participants. TemRO and TemRA cells are split into early, intermediate, and late differentiation subsets. (c) Gating strategies for the CD4 T-cell subsets. A representative example is shown. (d) A cumulative schematic overview of the geometric mean values of absolute numbers of CD4 naive, CM, TemRO, and TemRA cells in CMV− and CMV+ participants. TemRO and TemRA cells are were split into early, intermediate, and late differentiated subsets. The Mann Whitney U test was used for statistical analysis. *p < 0.05, **p < 0.01, ****p < 0.0001 (n = 250).

Figure 2. The combined effects of gender and CMV on the absolute numbers of CD8 T-cell subsets.

(a) A cumulative schematic overview of the geometric mean values of absolute numbers of CD8 naive, CM, TemRO, and TemRA cells in CMV+ and CMV− males and females. (b) Absolute numbers of CD8 naive T-cells in CMV+ and CMV− males and females. (c) Absolute numbers of CD8 CM T-cells in CMV+ and CMV− males and females. (d) A cumulative schematic overview of the geometric mean values of absolute numbers of early, intermediate, and late differentiated subsets within the CD8 TemRA cells in CMV+ and CMV− males and females. The number of total CD8 TemRA cells was compared between the groups. (e) Absolute numbers of CD8 TemRA late cells in CMV+ and CMV− males and females. The Geometric mean is indicated in the graphs, and the Kruskal-Wallis test was used for statistical analysis. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 after Bonferroni correction (n = 250).

Figure 3. The combined effects of gender and CMV on the absolute numbers of CD4 T-cell subsets.

(a) A cumulative schematic overview of the geometric mean values of absolute numbers of CD4 naive, CM, TemRO, and TemRA cells in CMV+ and CMV− males and females. The number of total CD4 T-cells was compared between the groups. (b) Absolute numbers of CD4 naive T-cells in CMV+ and CMV− males and females. (c) Absolute numbers of CD4 CM T-cells in CMV+ and CMV− males and females. (d) A cumulative schematic overview of the geometric mean values of absolute numbers of early, intermediate, and late differentiated subsets within the CD4 TemRA cells in CMV+ and CMV− males and females. The number of total CD4 TemRA cells was compared between the groups. (e) Absolute numbers of CD4 TemRA late cells in CMV+ and CMV− males and females. (f) Absolute numbers of T_FH cells in CMV+ and CMV− males and females. The Geometric mean is indicated in the graphs, and the Kruskal-Wallis test was used for statistical analysis. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 after Bonferroni correction (n = 250).

Figure 4. The combined effects of gender and CMV on the absolute numbers of CD4+CD45RA+CD25^dim T-cells and Treg cells.

(a) Gating strategies for the different cell subsets. A representative sample is shown. (b) Absolute numbers of CD45RA+CD25^dim T-cells in CMV+ and CMV− males and females. (c) Absolute numbers of Treg cells in CMV+ and CMV− males and females. (d) Absolute numbers of naive Treg cells in CMV+ and CMV− males and females. (e) Absolute numbers of memory Treg cells in CMV+ and CMV− males and females. The Geometric mean is indicated in the graphs, and the Kruskal-Wallis test was used for statistical analysis, *p < 0.05, **p < 0.01, after Bonferroni correction (n = 250).