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Section 7. Medical science
Israilov Radjab Israilovich, MD Professor of the department of pathology, Tashkent Medical Academy, E-mail: [email protected] Isoev Golib, Chair assistant of the department of forensic medicine and pathology, Samarkand Medical Institute, Eshbaev Erkin Abdukhalimovich, Chair assistant of the department of pathology, Tashkent Medical Academy
Morphological condition of the thymus in neonatal sepsis
Abstract: In this paper it's conducted a study of clinical and anamnestic data and features of morphological and morphometry changes of the thymus in infants who died from various forms of sepsis. Morphologically it's marked metaplasia of reticuloepithelium to reticulosis and sclerosis, the disappearance of lymphocytes and cell-nannies from the parenchyma of the thymus. As a result of prolonged exposure to infectious agents in the thymus completely blocked all the morphological and functional elements and occurs in the thymus immunogenesis paralysis.
Keywords: sepsis, newborn, thymus, immune deficiency, morphology.
The essence of sepsis is the body's inability to destroy microbes, primarily associated with immunodeficiency condition (IDC) [1; 2; 3]. The condition may be a background, i. e. to available in the body prior to infection, as well as naturally occurring in it as a result of pathogens and their toxins, and due to therapy. Thus, sepsis almost always occurs in a child with any background state, which is usually accompanied by a IDC. Infectious diseases in immunodeficiency conditions are especially gravity and duration of the current, the development ofunusual complications, often sepsis [2; 3; 4]. Thus, in the etiology of infectious processes the primary role usually belongs to microorganisms with low pathogenicity. If the defect of cell-mediated immunity infectious diseases are mainly caused by fungi, viruses and gram-negative flora, with defect of humoral immunity — gram-positive bacteria.
Until now is still little studied morphofunctional state organs of immunity, in particular the central organ — thymus in sepsis in newborns [5; 6]. Particularly, these morphological changes in the thymus, resulting in various infectious diseases remains controversial. In recent years in pediatrics is a particularly urgent problem of the growth of immunodeficiency conditions, developing under the influence of environmental, genetic and infectious factors.
Given the above, this paper studied the clinical and anamnestic data and features of morphological and morphometric changes of the thymus in infants who died from various forms of sepsis. Clinical and morphological analysis was performed taking into account the state of term and preterm, malnutrition and premorbid background diseases.
Material and methods. The object of the study were 36 thymus of newborn infants who died in infancy from sepsis. During the autopsy of corpses was isolated thymus, were weighed and determined by the weighting factor of the thymus (WFT). For histological examination of the thymus slices were fixed in 4% formalin solution, phosphate buffer and then dehydrated in alcohols embedded in paraffin. Slicers 5-8 micrometers of thickness were stained with hematoxylin and eosin, Van Gieson and Schick reaction. To unify accounting thymus morphological changes in the conditions of the newborn and various pathologies developed an algorithm for evaluation of morphological characters.
The results of clinical and morphological analysis of observations with sepsis showed that the disease as the most severe form of the infection is common in children, developed in preterm (34.7%), malnutrition (64.3%), in the presence of premorbid background (rachitis, anemia) — 51.5%. Great importance in the development of sepsis it took place different birth defects of organs and tissues, including congenital heart disease (23.8%), the brain (14.6%), kidney and liver (7.3%) and other congenital malformations (13,1%). These defects are more common in young infants, and often leads to septic lesions of the lung, colon, brain, and serous cavities.
Pathomorphological it's revealed bilateral macrofocal pneumonia with abscess formation and necrosis of the lesion areas, ul-cer-necrotic, fibrotic and ulcerative enterocolitis, sometimes with metastatic abscesses in the liver. Purulent metastases were also found in the brain, the epicardium, in rare cases, there was purulent peritonitis. In the age group of 7-12 months sepsis met as in the previous groups, children with artificial or mixed feeding, and as a complication ofviral and bacterial pneumonia, enterocolitis caused by pathogenic microbes occurring in the form of septicemia.
Thus, sepsis develops in frail children in a reduced immunological reactivity of the microorganism in the presence of premorbid background, runs hard, with polymorphic lesions of the internal organs, as pointed out by other authors (2,4,). It should be emphasized that very often immunodeficiency child's development even sepsis caused by opportunistic microorganisms. Our studies have shown that sepsis in one year-old children is caused mainly by opportunistic microbes (75.7%), such as E. coli, klebsiella, pseudomonas aeruginosa, staphylococcus epidermidis, proteus, joined viral infection, yeast and molds.
Immunological study found that the content of immuno-globulins and T- and B-lymphocytes fluctuated depending on the degree of prematurity and sepsis severity. Pyosepticemia on the background of prematurity, premorbid conditions and congenital malformation characterized by a significant decrease in the level of immunoglobulins of all classes. Also lowered blood cortisol level and immunoglobulin E. In septicemia accession viral infection marked increase in levels of immunoglobulin G to 16.7 g/l, cortisol up to 10,256.31 nmol/l. In the age group 7-12 months in almost
Morphological condition of the thymus in neonatal sepsis
all cases, elevated levels of immunoglobulin M, on average — 4,03± 0,19 g/l and the level of immunoglobulin A (0,31± 0,05) and G (6,55± 1,33) g/l relatively low.
In the diagnosis of secondary immunodeficiency in children, we take into account the clinical history, when there is the presence of the primary infectious diseases caused by viruses, virulent bacteria, parasites, and also when there are metabolic diseases, such as thesaurismoses and nutrition — malnutrition, anemia etc.
Pathomorphologically secondary immunodeficiencies manifest IV-V phases of accidental transformation, the acquired atrophy of the thymus. In peripheral organs immunogenesis — devastation not function structurally zones, and their replacement by the reticular connective tissue, as well as the absence of lymphocyte activation, bright breeding centers.
When infectious diseases according to the statute of limitations of the disease observed in the thymus various phases of accidental transformation. In the initial stages of viral infection, influenza and more adenoviral infection, thymus somewhat increased and edematous. Microscopically observed loosening of the layers due to swelling of the thymus, lymphocytes and a massive collapse of reticuloepithelial cells. Especially pronounced decay of lymphocytes was located in the subcapsular zone macrophages appeared larger and nurse cells, a large number of phagocytic cells. The medulla also lymphocytes are able to karyolysis and karyopyknosis; Hassall's corpuscles are increased, they are adjacent disintegrated lymphocytes and macrophages. In this layer, there are large cells with hyperchro-matic nuclei, resembling viral metaplasia cells of other organs.
In later stages of the disease is marked decrease in the volume of the cortex and medulla of the expansion. This process is accompanied by a thickening of the interstitial tissue by reticulosis and sclerosis. In the cortex, reticular cells predominate over the lymphocytes, the latter are located primarily in the cytoplasm of cells nurses. Reticuloepithelial cytoplasma undergoes dystrophic changes and breaks. Intercellular distance extended.
In subsequent stages begins lobules collapse of the thymus, the lymphocytes in the cortex almost disappear reticuloepithelium breaks, sometimes there are giant cells with large hyperchromatic
nuclei. In this phase accidental transformation of lymphocytes predominate in the medulla and are active in blasttransformated state. On the part of the interstitial tissue fibrosis is marked with a predominance of connective layers of fibrous structures; lymphatic vessels subsides. Reticuloepithelial cells that lie on the basement membrane, in metaplasia reticulum, then the connective tissue cells become spindle-shaped and grow in the direction of the parenchyma of the thymus. First, they take the cortical layer, and then in the form of strands enter the medulla between Hassall's corpuscles. In the thymus lymphocytes almost determined Hassall's corpuscles consist of scaly calcined mass. The ratio of the thickness of the parenchyma of the thymus and the interstitial tissue favors the stroma.
Thus comes the acquired atrophy of the parenchyma of the thymus with complete metaplasia reticuloepithelium in reticulosis and sclerosis, the disappearance of the parenchyma of the thymus lymphocytes and cells — nurses, breach the basement membrane of the cortex, consisting of reticular tissue, obliteration of the lymphatic vessels and cracks interlobular space and lobular perivascular space, where It occurs in normal lymphocyte recirculation, sclerotherapy of postcapillary venules of the parenchyma of the thymus. In short, as a result of prolonged exposure to pathogens in the thymus completely blocked all the morphological and functional elements and occurs in the thymus paralysis immunogenesis. Consequently occurs delymphotisation T-dependent areas of peripheral lymphoid organs, disturbed relationship of T and B lymphocytes occurs hypoplasia and second B-dependent areas.
Conclusions
Histological measurements study of the thymus with acquired immunodeficiency showed that its mass is reduced by half compared with the control group and averaged 6,4± 0,8 g, its weight index was also significantly below normal (1,03± 0,17). Slices thymus evenly collapsed, their diameter was 1164± 87 micrometers, of which accounted for 497± 53 micrometers for cortex, 667± 71 micrometers — on the brain. There is thickening of the stroma — 288± 23 micrometers and the coefficient of correlation of the stroma and the parenchyma was 0,24± 0,04 micrometers, which is significantly higher than the norm.
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