Splenomegaly and other disorders of the spleen

Mapping Intimacies ◽

10.1093/med/9780199568741.003.0035 ◽

2018 ◽

Author(s):

Chris Bunch

Keyword(s):

Particulate Matter ◽

Immune Responses ◽

Lymphoid Tissue ◽

Lymphoid Organ ◽

Dual Role ◽

White Pulp ◽

Humoral Immune ◽

Humoral Immune Responses ◽

Upper Abdomen ◽

Red Pulp

The spleen is a predominantly lymphoid organ, normally about the size of a clenched fist located beneath the diaphragm in the left upper abdomen. It has a dual role as a filter for the circulation, and a primary lymphoid organ in its own right. About three-quarters of its volume is a matrix of capillaries and sinuses (the red pulp), through which blood is able to percolate slowly and come into contact with fixed macrophages, which are able to remove senescent or damaged red cells, or other particulate matter such as bacteria. The lymphoid tissue is organized into scattered follicles (the white pulp), which have a particularly important role in initiating primary humoral immune responses and antibody (IgM) synthesis. The spleen commonly enlarges when either its filtration function is increased—as in haemolysis—or it is stimulated by infection or inflammation. It may also be involved in myeloproliferative and lymphoproliferative neoplasias. This chapter covers hypersplenism, splenectomy, hyposplenism, overwhelming post-splenectomy infection (OPSI), and other infections in hyposplenic patients.

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Splenic Mechanisms of Thrombocytopenia

Blood ◽

10.1182/blood.v130.suppl_1.sci-33.sci-33 ◽

2017 ◽

Vol 130 (Suppl_1) ◽

pp. SCI-33-SCI-33

Author(s):

John W. Semple

Keyword(s):

Immune Responses ◽

Reticuloendothelial System ◽

Lymphoid Organ ◽

The Body ◽

White Pulp ◽

Cellular Mechanisms ◽

Venous Circulation ◽

Destructive Processes ◽

Clinical Conditions ◽

Red Pulp

The spleen is the largest secondary lymphoid organ in the body and contains up to 25 percent of the body's lymphocyte populations. It is not only responsible for initiating immune responses against a multitude of infectious antigens within its white pulp, it also has the exquisite ability to filter the blood and remove, for example, senescent erythrocytes and platelets. This natural process is carried out within the red pulp of the spleen which is composed monocyte-rich connective tissue cords of Billroth intertwined with sinus cavities lined by parallel-oriented endothelial cells that have interendothelial slits which allow for the mechanical sorting of "old" cells. This occurs because of the inability of the senescent cells to properly migrate through the endothelial fenestrae into the venous circulation allowing them to be identified by cells of the reticuloendothelial system (RES) and quickly destroyed by phagocytosis. This process also allows for the efficient recycling of iron from destroyed erythrocyte hemoglobin molecules. There are a wide variety of clinical conditions that can significantly alter the ability of the RES to destroy blood cells including hereditary blood cell defects, inflammation, cancer and abnormal immune responses. This lecture will focus on the central role that the spleen plays in not only generating immune responses against platelets but also in primarily causing the destruction of both senescent and antibody-opsonized platelets leading to thrombocytopenia. It will discuss the soluble and cellular mechanisms of splenic sequestration, destruction and the ability of the spleen to modulate anti-platelet immunity. Mechanisms involving complement activation, Fc Receptor-mediated phagocytosis, antibody dependent cellular cytotoxicity and platelet self-destruction will be addressed. It will compare the spleen's platelet destructive capabilities with other organs, particularly the liver and will detail how immune responses generated in the white pulp can modulate platelet destructive processes in the red pulp. Disclosures Semple: Amgen: Consultancy, Honoraria, Speakers Bureau; Rigel: Consultancy, Honoraria; UCB: Consultancy, Honoraria.

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Microanatomy of Lymphoid Tissue During Humoral Immune Responses: Structure Function Relationships

Annual Review of Immunology ◽

10.1146/annurev.iy.07.040189.000515 ◽

1989 ◽

Vol 7 (1) ◽

pp. 91-109 ◽

Cited By ~ 188

Author(s):

A K Szakal ◽

M H Kosco ◽

J G Tew

Keyword(s):

Immune Responses ◽

Structure Function ◽

Lymphoid Tissue ◽

Humoral Immune ◽

Humoral Immune Responses

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Noninfectious X4 but Not R5 Human Immunodeficiency Virus Type 1 Virions Inhibit Humoral Immune Responses in Human Lymphoid Tissue Ex Vivo

Journal of Virology ◽

10.1128/jvi.78.13.7061-7068.2004 ◽

2004 ◽

Vol 78 (13) ◽

pp. 7061-7068 ◽

Cited By ~ 7

Author(s):

Wendy Fitzgerald ◽

Andrew W. Sylwester ◽

Jean-Charles Grivel ◽

Jeffrey D. Lifson ◽

Leonid B. Margolis

Keyword(s):

T Cells ◽

Immune Responses ◽

Lymphoid Tissue ◽

Ex Vivo ◽

Humoral Immune ◽

Humoral Immune Responses ◽

Immunodeficiency Virus ◽

Human Lymphoid Tissue ◽

Hiv 1

ABSTRACT Ex vivo human immunodeficiency virus type 1 (HIV-1) infection of human lymphoid tissue recapitulates some aspects of in vivo HIV-1 infection, including a severe depletion of CD4+ T cells and suppression of humoral immune responses to recall antigens or to polyclonal stimuli. These effects are induced by infection with X4 HIV-1 variants, whereas infection with R5 variants results in only mild depletion of CD4+ T cells and no suppression of immune responses. To study the mechanisms of suppression of immune responses in this ex vivo system, we used aldrithiol-2 (AT-2)-inactivated virions that have functional envelope glycoproteins but are not infectious and do not deplete CD4+ T cells in human lymphoid tissues ex vivo. Nevertheless, AT-2-inactivated X4 (but not R5) HIV-1 virions, even with only a brief exposure, inhibit antibody responses in human lymphoid tissue ex vivo, similarly to infectious virus. This phenomenon is mediated by soluble immunosuppressive factor(s) secreted by tissue exposed to virus.

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Different Immune Responses of the Lymphoid Organ in Shrimp at Early Challenge Stage of Vibrio parahaemolyticus and WSSV

Animals ◽

10.3390/ani11082160 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2160

Author(s):

Fuxuan Wang ◽

Shihao Li ◽

Fuhua Li

Keyword(s):

Immune Responses ◽

Vibrio Parahaemolyticus ◽

Early Stage ◽

Enrichment Analysis ◽

Lymphoid Organ ◽

Receptor Interaction ◽

Pathway Enrichment Analysis ◽

Immune Functions ◽

Humoral Immune ◽

Humoral Immune Responses

The lymphoid organ is an essential part of the immune system involved in cellular and humoral immune responses in shrimp. However, its roles in the immune responses against different pathogens are still largely unclear. In the present study, transcriptomic analysis was applied to compare the differentially expressed genes (DEGs) in the lymphoid organ of shrimp after Vibrio or WSSV challenge. In total, 2127 DEGs were screened in the lymphoid organ of shrimp at 6 h post Vibrio parahaemolyticus injection, and 1569 DEGs were obtained at the same time after WSSV challenge. KEGG pathway enrichment analysis of these DEGs revealed that two significantly enriched pathways including “neuroactive ligand–receptor interaction” and “protein digestion and absorption” were responsive to both pathogens. In contrast, “lysosome” was the significantly enriched pathway only in Vibrio challenge whereas carbohydrate metabolism related pathways were the significantly enriched pathways only in WSSV challenge. Further analysis on immune-related DEGs showed that Vibrio challenge induced broad immune responses in the lymphoid organ including activation of several pattern recognition receptors, the proPO activating system, phagocytosis related genes, and immune effectors. In contrast, the immune responses seemed to be inhibited after WSSV infection. The data suggest that the shrimp lymphoid organ plays different functions in response to the infection of distinct pathogens at the early stage, which provides new insights into the immune functions of lymphoid organ in shrimp.

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