The pathogenesis of juvenile chronic arthritis probably does not differ in principle from the pathogenesis of RA. At the same time, it remains unclear why the course of UXA, its prognosis, and in some cases curability still have certain differences from adult RA. In this respect, too, it is possible to express only an assumption.
It is well known that children, in response to antigenic irritation, react with a significantly greater activation of B-lymphoid systems compared to adults. In this connection, generalized reactions with a predominantly exudative inflammation are more characteristic of childhood age. It is probably this circumstance that can explain the fact that with YUHA, compared with adult RA forms, flow variants with systemic manifestations are much more common and a smaller proportion is exclusively articular forms, especially with a subacute course and a predominantly proliferative pattern of changes.
The exudative nature of inflammation, typical for children, may determine a lower frequency and rate of bone tissue destruction followed by disability of the patient by the musculoskeletal system due to the fact that in these conditions the killer activity of T-lymphocytes is suppressed, which is given a certain role in destruction of the affected tissue.
Above, when discussing the possible ways of occurrence of deficient states in the regulation of the immune response, the question was discussed that, probably, in various forms of RA, different variants of such disorders may occur. It is not excluded that the ratio of the described mechanisms varies significantly in children and adults.
In particular, such mechanisms of disease development as a decrease in the suppressor function of T lymphocytes with hyperactivity of the B lymphoid system in children may have a transient character and not lead to a subsequent uncontrollable aggression of the autoimmune process. A well-known confirmation of this point of view are the peculiarities of the age and sex distribution of the disease . The study of the “infant peak” of the incidence of UXA (1–5 years) showed significant heterogeneity in the course of the disease forms that occur at this age. Along with cases of typical rheumatoid arthritis with polyarthritis, there were at least two forms with specific age and sex determination. The first of them, systemic, arising on the basis of constitutional features of immunological reactivity, which is often combined with immunodeficiency states. The second form is relatively benign oligomonoarthritis of girls. It cannot be ruled out that the latter forms are closely related to the age-related transient rearrangements of the hormonal and immunological regulation mechanisms that arise in the period of the first growth shift. Curious,that the age distribution of UHA closely correlates with the incidence of acute leukemia in children, mainly lymphoblastic (as is known in the pathogenesis of acute leukemia, an important role is played by impaired regulation of cell maturation). The last parallels are also particularly significant because they can be distributed far beyond the children’s age, since leukemias and RA are becoming more frequent in the age group of 45–50 years.leukemia and RA concurrently become more frequent in the age group of 45–50 years.leukemia and RA concurrently become more frequent in the age group of 45–50 years.
The specific mechanisms of such phenomena are not entirely clear, however , the following concepts are possible:
1. In the period of intensive stretching of children under the influence of somatotropic hormone, somatomedins and thyroxins, specific conditions are created for the instability of the microenvironment of bone marrow lymphoid cells with a high probability of impaired differentiation, which can result in impaired immunological control and transient autoimmune reaction in girls and leopard. tia a boy.
2. The same conditions arising at the age of the “infant peak” are favorable for the activation of intracellular retro viruses or Epstein-Barr virus, which can also lead to impaired immunological regulation.
It is also possible that in childhood more often than in adults, lack of immunoregulation is secondary in nature, associated with transferred, especially viral diseases and other factors. Under these conditions, it is possible to restore an imbalance and stop the autoimmune process, especially in those cases when adequate therapy is carried out on the disease.