Transcript Hyposplenism

Hyposplenism
Presented by: Melissa Smith
Overview
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Definition of Hyposplenism
Medical History
The function of the spleen
Congenital asplenia vs. splenectomy
Immunological consequences of
Hyposplenism
Diagnosis and complications
What is Hyposplenism?
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Hyposplenism is the lack of a spleen or
its function
The rare genetic disorder- Congenital
Asplenia
The surgical removal of the spleensplenectomy
Results in severe immunological
consequences.
History
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Immunological importance of the
spleen
– Morris and Bullock-1919
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First post-splenectomy infection
– O’Donnell-1929
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Effects of Hyposplenism
– King and Shumacker-1952
The Spleen
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Largest lymphoid tissue of the body
Serves two main functions
– Filters blood to remove damaged/old RBC- red pulp
– Serves as secondary lymphoid tissue by removing
infectious agents and using them to activate lymphocyteswhite pulp
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A significant reservoir for T lymphocytes
Plays an active role in the production of IgM
antibodies and complement
Has significant role in the functional maturation of
antibodies
Anatomy of Spleen
Spleen Structure
The white pulp is circular in
structure and is made up mainly
of lymphocytes. It functions in a
manner similar to the nodules of the
lymph node.
The red pulp surrounds the white
pulp and contains mainly red blood
cells and macrophages. The main
function of the red pulp is to
phagocytize old red blood cells.
White Pulp
Red Pulp
Congenital Asplenia
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Autosomal recessive genetic disorder
Believed to be caused by absence of
the Hox 11 gene in the embryo
Causes decreased adaptive immune
response
Associated with structural
abnormalities in other organs of the
body- cause death in infancy
Splenectomy
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Removal of spleen tissue (partial or
complete)
Usually needed because of trauma
Residual splenic function in ¼ to ⅔ of
patients
IgM levels decreases, IgG levels
remain constant or increase, IgA and
IgE levels increase
Immunological
Consequences
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Causes slower and incomplete adaptive immune
response against bacteria
Low levels of tuftsin, which stimulates phagocytosis
by neutrophils, macrophages, and monocytes
Decreased neutrophil and macrophage activity
Increased NK cell activity
Limited capacity of circulating B-cells to
differentiate into antibody-secreting cells
Decreased level of T-cells
Diagnosis
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Determined by anatomic presence or
absence of the organ, its size, and any
lesions.
Function can be assessed by
– Radiologic Techniques
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X-ray, ultrasound, tomography, MRI, radionucleotide
scanning
– Morphologically
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Peripheral blood smear- presence of Howell-Jolly
bodies
Howell Jolly bodies
Howell-Jolly
bodies are
round, purple
staining nuclear
fragments of
DNA in the red
blood cell
Complications
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Lifelong risk for Overwhelming Postsplenectomy
infection (OPSI)
– Caused by Streptococcus pneumoniae and gram negative
bacteria
– Initial Symptoms: fever, chills, muscle aches, headache,
vomiting, diarrhea, and abdominal pain
– Progressive symptoms: bacteremic septic shock, extremity
gangrene, convulsions, and coma
– Mortality rate of 50-80%
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from onset of initial symptoms, 68% of those deaths occur
within 24 hours and 80% occur within 48 hours
– Prevention: routine vaccinations and prophylactic
antibiotics
Summary
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Hyposplenism is the lack of a spleen or its
function
Can be either genetic or surgically induced
It has detrimental effects on the immune
system by decreasing the body’s ability to
fight bacterial infections and reducing the
adaptive immune response
Resources
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Asplenia. Mudra Kumar, MD, MBBS, MRCP. EMedicine. 19 September 2005.
http://www.emedicine.com/ped/topic150.htm
Asplenia Defined. Families.com. 19 September 2005. http://encyclopedias.families.com/asplenia-112115-gecd
Bowdler, Anthony J.. The complete spleen : structure, function, and clinical disorders . 2nd ed. Totowa,
N.J. :
Humana Press, 2002.
Brigden, M. L. Detection, education and management of the asplenic or hyposplenic patient [a patient
information handout is provided]. American Family Physician v. 63 no. 3 (February 1 2001) p.
499-508
Feder, H. M. J., et. al., Assessment of splenic function in familial asplenia. The New England Journal of
Medicine v. 341 no. 3 (July 15 1999) p. 210-12
Gilbert-Barness, Enid., Diane E. Debich-Spicer. Handbook of pediatric autopsy pathology. Totowa, N.J.
: Humana Press, c2005.
Kanzler, B., et. al., Hox11 acts cell autonomously in spleen development and its absence results in
altered cell fate of mesenchymal spleen precursors. Developmental Biology v. 234 no. 1 (June
1 2001) p. 231-43
Neiman, Richard S., Attilo Orazi. Disorders of the spleen . 2nd ed. Philadelphia : W.B. Saunders,
c1999.
Romanovsky, A. A., et. al., The spleen: another mystery about its function [Editorial]. American Journal
of Physiology v. 284 no. 6 (June 2003 pt2) p. R1378-9
Sunder-Plassmann, G., et. al., Functional asplenia and vasculitis associated with antineutrophil
cytoplasmic antibodies. The New England Journal of Medicine v. 327 (August 6 1992) p. 437-8
Tice, A. Hope for patients with asplenia or hyposplenism [editorial]. American Family Physician v. 63 no.
3 (February 1 2001) p. 439-40