The goal of this study was to trace the course of multiple sclerosis (MS) by evaluating the lymphocyte subpopulation counts and the levels of CD4+ and CD8+ T cell activation using flow cytometry. Samples obtained from healthy subjects (N = 40) and patients with MS (N = 290) were analyzed. Lymphocytes were labeled for the surface markers CD4+, CD8+, CD3+, CD16+, CD19+, CD45+, and CD53+ and the activation marker HLA-DR+. Cell counts were then determined using flow cytometry. A high degree of inter-individual variability was observed in the counts of all lymphocyte subtypes in the MS group. A significantly lower proportion of CD3+ T cells (69 ± 14 % in healthy subjects and 60 ± 17 % as a percent of total lymphocytes in MS patients), CD4+ T cells (41 ± 11 and 28 ± 18 %, respectively), and a significantly higher proportion of NK T cells (12 ± 5 and 25 ± 21 %, respectively) were observed in patients with MS than in healthy subjects. These differences led to a lowered CD4+/CD8+ T cell ratio. Furthermore, a significantly lower proportion of activated CD4+ T cells (HLA-DR+ CD4+; from 48 ± 10 to 38 ± 15 % as a percent of CD4+ cells) was observed in patients with MS than in healthy subjects. The high level of inter-individual variability in lymphocyte cell counts and the counts of activated T cells suggest that MS is a complex and heterogeneous disease.
Keywords: CD4+ T helper cells; CD8+ cytotoxic T cells; T lymphocytes; multiple sclerosis.