Autosplenectomy
An autosplenectomy (from 'auto-' self, '-splen-' spleen, '-ectomy' removal) is a negative outcome of disease and occurs when a disease damages the spleen to such an extent that it becomes shrunken and non-functional.[1] The spleen is an important immunological organ that acts as a filter for red blood cells, triggers phagocytosis of invaders, and mounts an immunological response when necessary.[2] Lack of a spleen, called asplenia, can occur by autosplenectomy or the surgical counterpart, splenectomy. Asplenia can increase susceptibility to infection.[3] Autosplenectomy can occur in cases of sickle-cell disease where the misshapen cells block blood flow to the spleen, causing scarring and eventual atrophy of the organ.[2] Autosplenectomy is a rare condition that is linked to certain diseases but is not a common occurrence. It is also seen in systemic lupus erythematosus (SLE).
Consequences[edit]
Absence of effective splenic function or absence of the whole spleen (asplenia) is associated with increased risks of overwhelming post-splenectomy infection, especially from polysaccharide encapsulated bacteria and organisms that invade erythrocytes.[4] People without a spleen have a weakened immune system, although other immune organs compensate for the missing spleen.[5] Vaccination against encapsulated bacteria and prophylactic antibiotics can be used to counteract lowered immunity in asplenic patients. Specifically, people without a spleen are recommended to be vaccinated against pneumonia, influenza, Haemophilus influenzae type b and meningococci.[5]
Testing for autosplenectomy[edit]
One of the spleen's main tasks is to filter the blood and remove and recycle damaged or old red blood cells.[6] Splenic function can be measured by filtering capabilities, as indicated by number of Howell-Jolly bodies or pitted erythrocytes in the blood.[2] Both of these tests examine whether or not the spleen is functioning normally by testing splenic outputs.
Howell-Jolly bodies[edit]
Howell–Jolly bodies are found on red blood cells and contain chromatin remnants from basophilic cells.[7] Under normal conditions, these nuclear remnants are removed from the blood by the spleen's filtering capabilities. Howell-Jolly bodies can be identified and quantified using a blood smear or by flow cytometry.[2] A high number of Howell-Jolly bodies is indicative of splenic hypofunction and potentially autosplenectomy.
Pitted erythrocytes[edit]
Erythrocytes with membrane pits can be indicative of splenic dysfunction as a healthy spleen clears blood of pitted erythrocytes. Pitted erythrocytes can be counted using Normarsky optics.[8] Humans with healthy spleens have less than two percent of their red blood cells contain pits. In comparison, a person with asplenia may have up to 50% of their red blood cells contain pits.[9]
Diseases that cause autosplenectomy[edit]
Sickle cell anemia[edit]
The most frequent cause of autosplenectomy is sickle cell anemia[10] which causes progressive splenic hypofunction over time. Increased deoxygenation causes sickling of red blood cells, which adhere to the spleen wall and splenic macrophages causing ischemia.[2] This ischemia can result in splenic sequestration, where large amounts of blood pool in the spleen but do not flow within vasculature.[11] This lack of blood flow can cause atrophy in the spleen and can lead to autosplenectomy.[citation needed]
Pneumococcal sepsis[edit]
Pneumococcal sepsis, or whole-body infection caused by the Streptococcus pneumoniae bacteria, has been reported to cause autosplenectomy but is a very rare and poorly understood complication of the infection.[12]
References[edit]
- ^ "Autosplenectomy" with sickle cell anemia, gross at WebPath, The Internet Pathology Laboratory for Medical Education at Mercer University School of Medicine. Retrieved September 10, 2011
- ^ a b c d e Brousse, Valentine; Buffet, Pierre; Rees, David (2014-07-01). "The spleen and sickle cell disease: the sick(led) spleen". British Journal of Haematology. 166 (2): 165–176. doi:10.1111/bjh.12950. ISSN 1365-2141. PMID 24862308. S2CID 40448991.
- ^ "Splenectomy Risks - Mayo Clinic". www.mayoclinic.org. Retrieved 2016-03-02.
- ^ Brigden, Malcolm L. (February 2001). "Detection, Education and Management of the Asplenic or Hyposplenic Patient - American Family Physician". American Family Physician. 63 (3): 499. Retrieved 2016-02-16.
- ^ a b "Splenectomy Results - Mayo Clinic". www.mayoclinic.org. Retrieved 2016-03-03.
- ^ "What Is the Spleen? Functions & Info | Children's Hospital Pittsburgh". www.chp.edu. Retrieved 2016-03-03.
- ^ Kirkineska, L (2014). "Functional hyposplenism". Hippokratia. 18 (1): 7–11. PMC 4103047. PMID 25125944.
- ^ Di Sabatino, Antonio (April 6, 2011). "Post-splenectomy and hyposplenic states". Lancet. 378 (9785): 86–97. doi:10.1016/s0140-6736(10)61493-6. PMID 21474172. S2CID 30554953.
- ^ "Red Blood Cell Pit Count". Red Blood Cell Lab. Children's Hospital Oakland Research Institute. 2010. Retrieved March 2, 2016.
- ^ Henry Knipe; Frank Gaillard. "Autosplenectomy". radiopaedia.org. Retrieved 30 December 2015.
- ^ Ashley-Koch, A (2000). "Sickle Hemoglobin (Hb S) Allele and Sickle Cell Disease: A HuGE Review" (PDF). American Journal of Epidemiology. 151 (9): 839–845. doi:10.1093/oxfordjournals.aje.a010288. PMID 10791557. Archived from the original (PDF) on 2015-09-06.
- ^ Santilli, Daniele (2003). "Autosplenectomy and Antiphospholipid Antibodies in Systemic Lupus Erythematosus: A Pathogenic Relationship?". Seminars in Arthritis and Rheumatism. 33 (2): 125–133. doi:10.1016/S0049-0172(03)00004-0. PMID 14625820.