We validated MRI lesion load, OCB and age at CIS as the strongest independent predictors of conversion to CDMS in this multicentre setting. A role for vitamin D is suggested but requires further investigation.

Intrathecal oligoclonal bands of the cerebrospinal fluid are considered the most important immunological biomarkers of multiple sclerosis. They typically consist of clonally expanded IgG antibodies that underwent affinity maturation during sustained stimulation by largely unknown antigens. In addition, ∼40% of patients with multiple sclerosis have oligoclonal bands that consist of expanded IgM antibodies. We investigated the molecular composition of IgM- and IgG-chains from cerebrospinal fluid of 12 patients with multiple sclerosis, seven patients with other neurological diseases, and eight healthy control subjects by high-throughput deep-sequencing and single-cell PCR. Further, we studied the expression of activation-induced cytidine deaminase, the key enzyme for affinity maturation of antibodies, in cerebrospinal fluid samples of 16 patients. From the cerebrospinal fluid of two multiple sclerosis patients we isolated single B cells and investigated the co-expression of antibody chains with activation-induced cytidine deaminase. In striking contrast to IgM-chains from peripheral blood, IgM-chains from cerebrospinal fluid of patients with multiple sclerosis or neuroborreliosis showed a high degree of somatic hypermutation. We found a high content of mutations that caused amino acid exchanges as compared to silent mutations. In addition, more mutations were found in the complementarity determining regions of the IgM-chains, which interact with yet unknown antigens, as compared to framework regions. Both observations provide evidence for antigen-driven affinity maturation. Furthermore, single B cells from the cerebrospinal fluid of patients with multiple sclerosis co-expressed somatically hypermutated IgM-chains and activation-induced cytidine deaminase, an enzyme that is crucial for somatic hypermutation and class switch recombination of antibodies and is normally expressed during activation of B cells in germinal centres. Clonal tracking of particular IgM(+) B cells allowed us to relate unmutated ancestor clones in blood to hypermutated offspring clones in CSF. Unexpectedly, however, we found no evidence for intrathecal isotype switching from IgM to IgG. Our data suggest that the intrathecal milieu sustains a germinal centre-like reaction with clonal expansion and extensive accumulation of somatic hypermutation in IgM-producing B cells.

In this study, the tolerability and safety of treatment with pulsed steroids and glatiramer acetate and the occurrence of clinical and radiological activity after natalizumab (NTZ) cessation in multiple sclerosis (MS) patients were assessed. MS patients with NTZ were discontinued after 2 years of treatment, or if adverse events or disease progressed during NTZ. They were offered as alternative treatment 1 g methylprednisolone per month during 3 months followed by daily 20 mcg glatiramer acetate and were prospectively studied. Adverse events, occurrence of immune reconstitution inflammatory syndrome, clinical exacerbations, and gadolinium-enhancing lesions in MRI performed at 3 and 6 months after NTZ cessation were recorded. EDSS change during follow-up was also recorded. A total of 18 MS patients entered the study and were followed up for a mean of 10 months (range 6-18 months). There were no significant adverse events. At month 3, no patient had clinical or radiological disease activity. At month 6, 16.6% of patients had had a relapse and 55.5% of patients showed gadolinium-enhancing lesions in the MRI. After 6 months, 33.3% of patients had a further relapse. There was no IRIS, severe relapses, or significant difference between EDSS at NTZ discontinuation and after follow-up. The alternative treatment with monthly prednisolone followed by GA prevents the development of IRIS, but not the return to previous inflammatory activity, which occurs between 5 and 6 months after NTZ withdrawal.

The objective in this paper is to compare the cumulative incidence and incidence density of therapy-related acute myeloid leukaemia in two cohorts of patients with multiple sclerosis treated with mitoxantrone, and with previously reported data in the literature. Six new cases of acute myeloid leukaemia were observed by prospectively following two Spanish series of 142 and 88 patients with worsening relapsing multiple sclerosis and secondary-progressive disease treated with mitoxantrone. A literature review shows 32 further cases of acute myeloid leukaemia reported, 65.6% of which are therapy-related acute promyelocytic leukaemia. Five cases in the cohorts fulfilled the diagnostic criteria for acute promyelocytic leukaemia, and one patient was diagnosed with pre-B-acute lymphoblastic leukaemia. Acute myeloid leukaemia latency after mitoxantrone discontinuation was 1 to 45 months. The accumulated incidence and incidence density was 2.82% and 0.62%, respectively, in the Valencian cohort, and 2.27% and 0.44% in the Catalonian cohort. In the only seven previously reported series, the accumulated incidence varied from 0.15% to 0.80%. The real incidence of acute myeloid leukaemia after mitoxantrone therapy in the multiple sclerosis population could be higher as evidenced by the growing number of cases reported. Haematological monitoring should continue for at least 5 years after the last dose of mitoxantrone. These data stress the necessity of re-evaluating this risk.