THE SIGNIFICANCE OF THE SPLEEN IN THE BODY'S IMMUNE SYSTEM

SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 11 NOVEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 77 THE SIGNIFICANCE OF THE SPLEEN IN THE BODY'S IMMUNE SYSTEM Sh.R. Davronova Abu Ali ibn Sino Bukhara State Medical Institute, Department of Histology, Cytology and Embryology, Uzbekistan https://doi.org/10.5281/zenodo.17744690 Abstract. The human immune system is a multilevel functional network of organs and tissues that provide constant monitoring of the body's internal environment and protection from foreign agents. The organs of the immune system include the thymus, bone marrow, lymph nodes, tonsils, intestinal plaques, and spleen. Among them, the spleen occupies a special position, being not only the largest peripheral lymphoid organ, but also a unique blood filter in which there is a close interaction of innate and adaptive immune defense mechanisms. Keywords: red and white pulp, lymphocytes, erythrocytes, platelets. Introduction. The relevance of studying the spleen is determined by its dual function— hematopoietic and immune. On the one hand, this organ provides blood filtration, the destruction of aging and defective erythrocytes, and the deposition of blood cells. On the other hand, it serves as an active center of immunogenesis, where antigen recognition, lymphocyte activation, antibody production, and the formation of immunological memory occur. Thus, the spleen not only participates in blood purification processes but also ensures an adequate immune response to antigenic exposure, maintaining the overall homeostasis of the organism. Modern experimental and morphological studies have demonstrated that the structural and functional organization of the spleen is extremely complex. Its white pulp contains highly specialized zones — periarteriolar lymphoid sheaths and lymphoid follicles — responsible for Tand B-lymphocyte activation. The red pulp, in turn, functions as a site of blood deposition, phagocytosis of cellular debris, and the removal of aging erythrocytes. Such morphological and functional compartmentalization ensures the coordinated participation of the organ in maintaining both cellular and humoral components of immunity. Interest in the study of the spleen has significantly increased in recent decades due to the development of immunohistochemical techniques, electron microscopy, and molecular methods that enable detailed examination of its cellular organization and participation in immune reactions. Particular attention has been devoted to the morphological changes of the spleen in infectious diseases, autoimmune processes, stress conditions, and surgical interventions. The clinical significance of the organ also deserves special mention. Loss of splenic function as a result of trauma or splenectomy is associated with a marked decrease in the body’s resistance, increased susceptibility to bacterial infections, and disruption of hematopoietic regulation. This emphasizes the need for a deeper understanding of its morphophysiological role and the development of strategies to preserve or partially restore splenic functions following surgical operations. Therefore, the study of the spleen represents not only morphological but also clinical importance. The aim of this review is to systematize current data on the structure, functions, and immunological significance of the spleen, as well as to analyze its role in maintaining homeostasis and forming the body’s defense mechanisms under normal and pathological conditions. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 11 NOVEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 78 Aim of the Study. The aim of this research is to clarify a number of questions concerning the structural organization of the spleen, its role in the immune response and overall regulation of the organism, by analyzing and studying its histomorphological architecture, antigen recognition capabilities, lymphocyte activation, phagocytic activity, and its significance in the development of immune reactions [8,9,10,11,12]. Morphological and Functional Structure. The spleen consists of several structural components, including the capsule, trabeculae, white and red pulp, as well as a specialized vascular system. Trabeculae, extending from the capsule, penetrate deep into the organ and contain blood vessels, smooth muscle fibers, and nerves that form a complex network of anastomoses. The capsule and trabeculae are composed of dense fibrous connective tissue containing numerous elastic and collagen fibers. In addition, these tissues contain smooth muscle cells that play an important role in regulating blood flow within the spleen [4]. Inside the spleen, two distinct regions can be distinguished: the white pulp and the red pulp. The white pulp consists of lymphoid tissue, including periarteriolar lymphoid sheaths (PALS) that contain T-lymphocytes. These sheaths surround the central arteries, forming a protective barrier. The white pulp also contains lymphoid follicles or nodules, which house B-lymphocytes. Upon exposure to antigens, B-lymphocytes become activated [5]. The red pulp, located between the lymphoid tissue and trabeculae, consists of two main components: splenic sinusoids and pulp cords (Billroth’s cords). The sinusoids represent large postcapillary vessels containing various cells such as erythrocytes, macrophages, and plasma cells. These blood cells are embedded within a complex network of reticular stromal cells that form the framework of the splenic cords. Lymphocytes are also found within this network [3]. It is well known that antigens entering the bloodstream are frequently directed to the spleen. Upon arrival, these antigens undergo phagocytosis by macrophages and lymphocytes within the microvessels of the marginal zone and adjacent areas of the red pulp. A small portion of antigens circulating beyond the protective layers provided by the mucous membranes and skin reaches the spleen and initiates an immune response. In contrast, the majority of antigens are neutralized within the lymph nodes [13,14]. The study of the histomorphological and anatomical structure of the white pulp revealed its active participation in immune responses, supported by periarteriolar lymphoid sheaths (T-cell immunity) and lymphoid follicles (B-cell immunity). Conversely, the red pulp performs phagocytic functions, clearing senescent erythrocytes and capturing antigens under the influence of splenic macrophages [7]. Moreover, the spleen stimulates Tand B-lymphocytes, further emphasizing its importance in antibody production and the formation of immunological memory. The spleen is an essential component of both the innate and adaptive immune systems, playing key roles in processes such as phagocytosis, antibody production, and activation of Tand B-lymphocytes. Understanding its histomorphological structure and functions provides deeper insight into the complex operation of the immune defense system, underscoring the importance of preserving this vital organ during surgical interventions. Furthermore, studies have demonstrated that the absence of the spleen significantly impairs immunity, necessitating additional vaccination and infection control measures in splenectomized patients. The spleen also participates in the destruction of red blood cells in hemolytic anemia, making it a crucial component in maintaining healthy hematopoiesis. Future research efforts should be directed toward developing strategies for restoring immune function after splenectomy to improve the overall health status of patients undergoing this surgical procedure [6,15,16,17]. SCIENCE AND INNOVATION INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 4 ISSUE 11 NOVEMBER 2025 ISSN: 2181-3337 | SCIENTISTS.UZ 79 Conclusion The spleen is an integral component of the immune system, combining the functions of blood filtration, storage of formed elements, and participation in immune reactions. It ensures the removal of aging erythrocytes and foreign particles from the bloodstream, plays a key role in Tand B-lymphocyte activation, the formation of immunological memory, and the maintenance of internal homeostasis. Modern morphological and functional studies confirm that the structural components of the spleen—the red and white pulp—are interrelated and provide coordinated activity of the innate and adaptive branches of immunity. 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