High correlations of anti-CMV titers with lymphocyte activation status and CD57 antibody-binding capacity as estimated with three-color, quantitative flow cytometry in blood donors.

Blood samples of 58 blood donors (ages 19-64 years, 31 males and 27 females) were investigated with three-color, quantitative flow cytometry. IgG anti-cytomegalovirus (CMV) was estimated with ELISA. Nineteen men and 21 women were found CMV-seropositive. The seropositive individuals (CMV-pos) compared to the seronegative ones (CMV-neg) presented no significant changes in the absolute number of lymphocytes or in the main lymphocyte subpopulations identified by CD20, CD3, CD4, and CD8. Nevertheless, CMV-pos showed significantly higher numbers of lymphocytes with the following phenotypes: CD4+HLA-DR+, CD8+HLA-DR+, CD8+CD45RA+ CD45RO+, and CD20+CD5+. The CD3+CD57+ subset of T lymphocytes was also significantly higher in CMV-pos (P < 0.0001), whereas the CD57+CD16 & CD56+CD3- NKC subset presented similar values in both groups. Higher values for the antibody-binding capacity of lymphocytes CD38 (P < 0.05) and CD45 (P = 0.02) antigens and of CD57 antigen on CD3+ lymphocytes (P < 0.0005) were found in the CMV-pos group. These results show that CMV upregulates the number of CD57 molecules on CD3+ and not on CD3- lymphocytes and suggest that the CD3 molecule or other molecules specifically present in T cells can play a role in CMV latency. The study also showed that CMV plays a major role in the maintenance of a fraction of lymphocyte in the activated state.