[The immunity during the pre-clinical period of type I diabetes mellitus].

The purpose of the study was to investigate the condition of immunity (blood lymphocyte immune phenotype and ultrastructure) in healthy children with a family background of type 1 diabetes mellitus (DM 1) having or not having diabetes-associated autoantibodies (DAAB). The subjects of the study were divided into three groups. Group 1 consisted of 90 children with a family background of DM 1 (first line relatives had DM 1), DAAB- (GADA, IA-2A, and IAA) positive or negative; group 2 consisted of 51 children with newly revealed DM 1; group 3 included 45 healthy controls, normoglycemic DAAB-negative children with no family background of DM 1. GADA, IA-2A, and IAA titers were measured using radioimmunoassay. The immune phenotype of lymphocytes (CD3+, CD4+, CDr8, CD20+, and CD56+ cells) were studied using flow cytometry (FACS-analysis); their ultrastructure was studied by means of electron microscopy. The study found a significantly lower total number of T-lymphocytes (CD3+ cells), T-helpers/inductors (CD4+ cells), and natural killer cells (CD56+ cells and large granule-containing lymphocytes) in the DAAB-positive children vs. the DAAB-negative ones and especially the controls. In the DAAB-positive children, electron microscopy found distinct changes in the ultrastructure of CD4+ lymphocytes and large granule-containing lymphocytes (CD56+ cells), which evidences changes in the secretory and cytostatic function. Such changes in the number and ultrastructure of these lymphocyte subpopulations are found in patients with newly revealed DM 1. Thus, immune changes happen in the organism of a healthy person a long time before clinical manifestations of DM 1 develop; these changes reflect a concealed autoimmune process in Langerhans islets. Detection of DAAB plays a significant role not only in studying poorly understood pre-diabetes nature, but also in the development of new, scientifically based methods of its prevention and treatment.