Anti-CD20 therapy corrects a CD8 regulatory T cell deficit in multiple sclerosis.

OBJECTIVE: To determine the effect of long-term anti-CD20 B-cell-depleting treatment on regulatory T cell immune subsets that are subnormal in untreated MS patients. METHODS: 30 clinically stable MS patients, before and over 38 months of ocrelizumab treatment, were compared to 13 healthy controls, 29 therapy-naïve MS, 9 interferon-ß-treated MS, 3 rituximab-treated MS, and 3 rituximab-treated patients with other autoimmune inflammatory diseases. CD8, CD28, CD4, and FOXP3 expression in peripheral blood mononuclear cells was quantitated with flow cytometry. RESULTS: CD8+ CD28- regulatory cells rose from one-third of healthy control levels before ocrelizumab treatment (2.68% vs 7.98%), normalized by 12 months (13.5%), and rose to 2.4-fold above healthy controls after 18 months of ocrelizumab therapy (19.0%). CD4+ FOXP3+ regulatory cells were lower in MS than in healthy controls (7.98%) and showed slight long-term decreases with ocrelizumab. CD8+ CD28- and CD4+ FOXP3+ regulatory T cell percentages in IFN-ß-treated MS patients were between those of untreated MS and healthy controls. INTERPRETATION: Long-term treatment with ocrelizumab markedly enriches CD8+ CD28- regulatory T cells and corrects the low levels seen in MS before treatment, while slightly decreasing CD4+ FOXP3+ regulatory T cells. Homeostatic enrichment of regulatory CD8 T cells provides a mechanism, in addition to B cell depletion, for the benefits of anti-CD20 treatment in MS.

Increased Percentage of CD8+CD28- Regulatory T Cells With Fingolimod Therapy in Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Fingolimod, an oral therapy for MS, decreases expression of membrane S1P1 receptors on CD4+ memory cells, causing their retention and deactivation in lymph nodes. We determined fingolimod effects on the number and proportion of potentially CNS-damaging CD8+CD28+ cytolytic T lymphocyte cells (CTLs) and on MS-depleted and dysfunctional CD8+CD28- anti-inflammatory suppressor/regulatory T cells (Treg) and on CD8+ T-cell expression of the CD69 activation/lymph node retention protein in MS. METHODS: CD8, CD28, CD4, and CD69 expression on peripheral blood mononuclear cells was measured with flow cytometry. In vitro concanavalin A (ConA) activation of T cells, including CD8+CD28- cells, was used to mimic inflammation. RESULTS: Fifty-nine patients with MS, 35 therapy-naive (16 clinically stable; 19 exacerbating) and 24 fingolimod-treated (19 clinically stable; 5 exacerbating), and 26 matched healthy controls (HCs) were compared. In therapy-naive patients, the CD8+ Treg percent of total lymphocytes was only 1/4 of HC levels. In fingolimod-treated patients, however, CD8+ Treg percentages rose to 2.5-fold higher than in HC and 10-fold higher than in therapy-naive MS. With fingolimod therapy, in contrast, CD8+ CTL levels were less than half of levels in HCs and therapy-naive patients. In HCs and all MS, activation with ConA strongly induced CD69 expression on CD4+ cells and induced 3-fold higher CD69 levels on CD8+ CTL than on CD8+ Treg. Fingolimod and analogs in vitro did not modify lymphocyte CD69 expression. Lower levels of CD69 on CD8+ Treg than on CTL may allow easier Treg egress from lymph nodes and enhance control of peripheral inflammation. In vitro activation reduced the already low CD8+ Treg population in therapy-naive MS, but only slightly altered Treg levels in fingolimod-treated MS. DISCUSSION: Fingolimod therapy markedly increases the percentage of CD8+ Treg in MS, reversing the low CD8+ Treg:CTL ratio seen in untreated MS. The increase in immune regulatory cells has potential therapeutic benefit in MS. Activation in vitro depletes CD8+CD28+CTL in patients with MS; the loss is more pronounced in older patients with MS. This suggests that inflammation can disrupt the tenuous immune regulation in MS, especially in older patients.