Clinical and immunological features of the pediatric multiple sclerosis

Introduction. The course of multiple sclerosis (MS) in children and adults has numerous differences, which may require the development of differentiated treatment approaches depending on the patient’s age. However, the pathogenetic basis of the above differences remains unclear. The objective was to evaluate the clinical features of pediatric MS and their relationship with the cytotoxic T-cell (Tcyt) subsets in peripheral blood. Methods and materials. The main group consisted of 33 patients with pediatric MS of adolescent age. In the main group and the comparison group of 22 adults with MS, clinical and MRI characteristics of the disease were assessed. In the main group, as well as in 28 adults with MS and 26 healthy adolescents, the main Tcyt subsets were identified, based on the expression of CD45RA and CD62L and co-expression of chemokine receptors CCR4, CCR6, CXCR3 and CXCR5. Results. The frequency of exacerbations and occurrence of highly active and rapidly progressing MS (HAMS) in pediatric MS was 1.5 times higher than in adults. An equivalent relationship between the severity of cerebellar disorders and HAMS was demonstrated both in the pediatric MS group and in adults. Adolescents with MS showed a significantly increased relative numbers of effector memory Tcyt expressing CCR6. For the first time, a relationship was determined between the effector Tcyt expressing CCR6 and highly active pediatric MS (p=0.04). A 2.5-fold increase of the relative numbers of CCR6-positive terminally differentiated Tcyt was found in patients with MRI activity compared to the patients in radiological remission (p=0.01). The results of ROC analysis showed high sensitivity (75.0 %) and specificity (89.7 %) of the CCR6+-positive effector memory Tcyt relative number in predicting the activity of the pediatric MS. Conclusions. The disability level has a significant relationship with the frequency of exacerbations in both pediatric MS patients and adults, and the frequency of exacerbations in pediatric MS patients during the first years of the disease is higher than in adults. The obtained results demonstrate a higher activity of T-cell component of the immune system in patients with pediatric MS compared to adults, in particular, various effector Tcyt subsets. The relative number of CCR6-positive effector memory Tcyt above 55.4 % can be considered as a prognostic marker of HAMS in pediatric MS.