HyposplenismHyposplenism

Presented by: Melissa SmithPresented by: Melissa Smith

OverviewOverview

Definition of HyposplenismDefinition of Hyposplenism Medical HistoryMedical History The function of the spleenThe function of the spleen Congenital asplenia vs. Congenital asplenia vs.

splenectomysplenectomy Immunological consequences of Immunological consequences of

HyposplenismHyposplenism Diagnosis and complicationsDiagnosis and complications

What is Hyposplenism?What is Hyposplenism?

Hyposplenism is the lack of a Hyposplenism is the lack of a spleen or its functionspleen or its function

The rare genetic disorder- The rare genetic disorder- Congenital AspleniaCongenital Asplenia

The surgical removal of the The surgical removal of the spleen- splenectomyspleen- splenectomy

Results in severe immunological Results in severe immunological consequences.consequences.

HistoryHistory

Immunological importance of the Immunological importance of the spleenspleen– Morris and Bullock-1919Morris and Bullock-1919

First post-splenectomy infectionFirst post-splenectomy infection– O’Donnell-1929O’Donnell-1929

Effects of HyposplenismEffects of Hyposplenism– King and Shumacker-1952King and Shumacker-1952

The SpleenThe Spleen

Largest lymphoid tissue of the bodyLargest lymphoid tissue of the body Serves two main functionsServes two main functions

– Filters blood to remove damaged/old RBC- red pulpFilters blood to remove damaged/old RBC- red pulp– Serves as secondary lymphoid tissue by removing Serves as secondary lymphoid tissue by removing

infectious agents and using them to activate infectious agents and using them to activate lymphocytes- white pulplymphocytes- white pulp

A significant reservoir for T lymphocytesA significant reservoir for T lymphocytes Plays an active role in the production of IgM Plays an active role in the production of IgM

antibodies and complementantibodies and complement Has significant role in the functional Has significant role in the functional

maturation of antibodiesmaturation of antibodies

Anatomy of SpleenAnatomy of Spleen

Spleen StructureSpleen Structure

The The white pulpwhite pulp is circular in is circular in

structure and is made up mainly structure and is made up mainly

of lymphocytes. It functions in a of lymphocytes. It functions in a

manner similar to the nodules of the manner similar to the nodules of the

lymph node. lymph node.

The The red pulpred pulp surrounds the white surrounds the white

pulp and contains mainly red blood pulp and contains mainly red blood

cells and macrophages. The main cells and macrophages. The main

function of the red pulp is to function of the red pulp is to

phagocytize old red blood cells.phagocytize old red blood cells.

White PulpWhite Pulp

Red PulpRed Pulp

Congenital AspleniaCongenital Asplenia

Autosomal recessive genetic Autosomal recessive genetic disorderdisorder

Believed to be caused by absence Believed to be caused by absence of the Hox 11 gene in the embryoof the Hox 11 gene in the embryo

Causes decreased adaptive Causes decreased adaptive immune responseimmune response

Associated with structural Associated with structural abnormalities in other organs of abnormalities in other organs of the body- cause death in infancythe body- cause death in infancy

SplenectomySplenectomy

Removal of spleen tissue (partial or Removal of spleen tissue (partial or complete)complete)

Usually needed because of traumaUsually needed because of trauma Residual splenic function in ¼ to Residual splenic function in ¼ to ⅔⅔

of patientsof patients IgM levels decreases, IgG levels IgM levels decreases, IgG levels

remain constant or increase, IgA remain constant or increase, IgA and IgE levels increaseand IgE levels increase

Immunological Immunological ConsequencesConsequences Causes slower and incomplete adaptive Causes slower and incomplete adaptive

immune response against bacteria immune response against bacteria Low levels of tuftsin, which stimulates Low levels of tuftsin, which stimulates

phagocytosis by neutrophils, macrophages, phagocytosis by neutrophils, macrophages, and monocytesand monocytes

Decreased neutrophil and macrophage Decreased neutrophil and macrophage activityactivity

Increased NK cell activityIncreased NK cell activity Limited capacity of circulating B-cells to Limited capacity of circulating B-cells to

differentiate into antibody-secreting cellsdifferentiate into antibody-secreting cells Decreased level of T-cellsDecreased level of T-cells

DiagnosisDiagnosis

Determined by anatomic presence or Determined by anatomic presence or absence of the organ, its size, and any absence of the organ, its size, and any lesions.lesions.

Function can be assessed by Function can be assessed by – Radiologic TechniquesRadiologic Techniques

X-ray, ultrasound, tomography, MRI, X-ray, ultrasound, tomography, MRI, radionucleotide scanningradionucleotide scanning

– MorphologicallyMorphologically Peripheral blood smear- presence of Howell-Jolly Peripheral blood smear- presence of Howell-Jolly

bodiesbodies

Howell Jolly bodiesHowell Jolly bodies

Howell-Howell-Jolly Jolly

bodies bodies are are

round, purple round, purple staining nuclear staining nuclear

fragments of fragments of DNA in the red DNA in the red

blood cell blood cell

ComplicationsComplications

Lifelong risk for Overwhelming Lifelong risk for Overwhelming Postsplenectomy infection (OPSI)Postsplenectomy infection (OPSI)– Caused by Caused by Streptococcus pneumoniaeStreptococcus pneumoniae and gram and gram

negative bacterianegative bacteria– Initial Symptoms: fever, chills, muscle aches, Initial Symptoms: fever, chills, muscle aches,

headache, vomiting, diarrhea, and abdominal painheadache, vomiting, diarrhea, and abdominal pain– Progressive symptoms: bacteremic septic shock, Progressive symptoms: bacteremic septic shock,

extremity gangrene, convulsions, and comaextremity gangrene, convulsions, and coma– Mortality rate of 50-80%Mortality rate of 50-80%

from onset of initial symptoms, 68% of those deaths from onset of initial symptoms, 68% of those deaths occur within 24 hours and 80% occur within 48 hoursoccur within 24 hours and 80% occur within 48 hours

– Prevention: routine vaccinations and prophylactic Prevention: routine vaccinations and prophylactic antibioticsantibiotics

SummarySummary

Hyposplenism is the lack of a spleen or Hyposplenism is the lack of a spleen or its functionits function

Can be either genetic or surgically Can be either genetic or surgically inducedinduced

It has detrimental effects on the It has detrimental effects on the immune system by decreasing the immune system by decreasing the body’s ability to fight bacterial body’s ability to fight bacterial infections and reducing the adaptive infections and reducing the adaptive immune responseimmune response

ResourcesResources

Asplenia. Mudra Kumar, MD, MBBS, MRCP. EMedicine. 19 September 2005. Asplenia. Mudra Kumar, MD, MBBS, MRCP. EMedicine. 19 September 2005. http://www.emedicine.com/ped/topic150.htm http://www.emedicine.com/ped/topic150.htm

Asplenia Defined. Families.com. 19 September 2005. Asplenia Defined. Families.com. 19 September 2005. http://encyclopedias.families.com/asplenia-112-http://encyclopedias.families.com/asplenia-112- 115-gecd115-gecd

Bowdler, Anthony J.. Bowdler, Anthony J.. The complete spleen : structure, function, and clinical disordersThe complete spleen : structure, function, and clinical disorders . 2nd . 2nd ed. Totowa, ed. Totowa, N.J. : N.J. : Humana Press, 2002.Humana Press, 2002.

Brigden, M. L. Detection, education and management of the asplenic or hyposplenic patient Brigden, M. L. Detection, education and management of the asplenic or hyposplenic patient [a patient [a patient information handout is provided]. American Family Physician v. 63 no. 3 information handout is provided]. American Family Physician v. 63 no. 3 (February 1 2001) p. (February 1 2001) p. 499-508499-508

Feder, H. M. J., et. al., Assessment of splenic function in familial asplenia. The New England Feder, H. M. J., et. al., Assessment of splenic function in familial asplenia. The New England Journal of Journal of Medicine v. 341 no. 3 (July 15 1999) p. 210-12Medicine v. 341 no. 3 (July 15 1999) p. 210-12

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Kanzler, B., et. al., Hox11 acts cell autonomously in spleen development and its absence Kanzler, B., et. al., Hox11 acts cell autonomously in spleen development and its absence results in results in altered cell fate of mesenchymal spleen precursors. Developmental Biology v. altered cell fate of mesenchymal spleen precursors. Developmental Biology v. 234 no. 1 (June 234 no. 1 (June 1 2001) p. 231-431 2001) p. 231-43

Neiman, Richard S., Attilo Orazi.Neiman, Richard S., Attilo Orazi. Disorders of the spleen Disorders of the spleen . 2nd ed. Philadelphia : W.B. . 2nd ed. Philadelphia : W.B. Saunders, Saunders, c1999.c1999.

Romanovsky, A. A., et. al., The spleen: another mystery about its function [Editorial]. Romanovsky, A. A., et. al., The spleen: another mystery about its function [Editorial]. American Journal American Journal of Physiology v. 284 no. 6 (June 2003 pt2) p. R1378-9of Physiology v. 284 no. 6 (June 2003 pt2) p. R1378-9

Sunder-Plassmann, G., et. al., Functional asplenia and vasculitis associated with Sunder-Plassmann, G., et. al., Functional asplenia and vasculitis associated with antineutrophil antineutrophil cytoplasmic antibodies. The New England Journal of Medicine v. cytoplasmic antibodies. The New England Journal of Medicine v. 327 (August 6 1992) p. 437-8327 (August 6 1992) p. 437-8

Tice, A. Hope for patients with asplenia or hyposplenism [editorial]. American Family Tice, A. Hope for patients with asplenia or hyposplenism [editorial]. American Family Physician v. 63 no. Physician v. 63 no. 3 (February 1 2001) p. 439-403 (February 1 2001) p. 439-40