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In 1855, Thomas Addison atGuy's Hospital described alethal, idiopathic anemia thatin 1872 was given the namepernicious anemia by Biemer.For decades following, acommonly held view was thatpernicious anemia reflectedthe positive-acting, deleteriousinfluence of an infectious agentor a microbial product. Apopular concept was that the

injurious agent caused excessive destruction ofred blood cells.

Clinical and autopsy studies subsequentlyestablished that pernicious anemia was morethan a disorder of red blood cells. Besidesreduced numbers of blood erythrocytes and lowconcentrations of hemoglobin, patients werefound to have excessive iron deposits in theliver, gastric glandular atrophy andachlorhydria, megaloblastic bone marrowhyperplasia, and profound demyelination andatrophy of sensory axons in the spinal cord.Under the microscope some cells of the bodythat normally turn over rapidly were found tobe increased in size. Large erythrocyticprecursors in the bone marrow were recognizedearly, but with time it became clear that theblood of patients with pernicious anemiacontained giant granulocytes and platelets, andthat large epithelial cells were present in theirgastric and vaginal washings.

Beginning in the early 1900’s anecdotal reportssuggested to a few investigators that perniciousanemia might be a nutritional deficiencydisease. In the 1920’s two milestonediscoveries were published, one by thepathologist George Whipple and colleagues atthe University of Rochester1, the other by twoclinical investigators, George Minot and WilliamMurphy, at Harvard Medical School2. Whippleshowed that anemia could be the result of anutritional deficiency. Minot and Murphydeveloped a special diet that could reverse thepathology of pernicious anemia and curepatients. This was a tremendous breakthroughbecause 1-2% of adults over age 50, primarilypeople of northern European ancestry, suffered

from this fatal disease. In 1934, Minot, Murphyand Whipple shared the Nobel Prize inPhysiology and Medicine for their discoveries.Their Nobel lectures – available on the Nobelwebsite (www.nobelprize.org) – provideinteresting historical information and dataabout their experiments. These milestonediscoveries launched decades of investigations,notably by W.B. Castle3, that uncovered thecomplex pathophysiological mechanismsunderlying pernicious anemia. Castle'sdiscoveries led to new treatments of thedisease that were more effective, bettertolerated by patients, and more affordable.

The importance of Whipple's work was that itfirmly established on a quantitative basis thatthe properties of food influenced bloodformation, a concept not previously accepted.Whipple was originally interested in themetabolism of biliary and blood pigments andhad developed a model of chronic anemia indogs by repeated phlebotomy. When he beganto investigate factors that influenced bloodregeneration in chronically anemic dogs,Whipple focused on diet. Of the various dietstested, he found that liver and liver extractswere the most effective, although feeding othermeats – kidney, muscle, or brain – alsostimulated hematopoiesis. The choice of liverwas fortunate. As others later pointed out, hadWhipple fed iron salts to the dogs, he likelywould have observed the same result since thedogs he studied undoubtedly suffered from irondeficiency anemia. Whipple's findings on theeffectiveness of liver feeding influenced Minotand Murphy to continue similar clinical studiesthey had been conducting in patients withpernicious anemia. A key element in thesuccess of those studies was the reliance onblood reticulocyte counts to assess bonemarrow responsiveness.

Once it was established that daily feedings oflarge amounts of liver or concentrated liverextracts induced varying degrees of remissionin pernicious anemia, the central questionbecame, "What is the active factor?" Castle3

discovered that daily administration by gastrictube of liquefied stomach contents from ahealthy person removed an hour after ingestion

Pernicious AnemiaRichard G. Lynch, MDOriginally published in ASIP Pathways, Volume 3, No. 4 - December 2008

Whipple GH, Hooper CW, RobscheitFS: Blood regenerationfollowing anemia. AmericanJournal of Physiology 1920, 53:236-262

Minot GR and Murphy WP:Treatment of pernicious anemiaby special diet. Journal of theAmerican Medical Association 1926,87:470-476

Castle WB: Observations of theetiologic relationship of achyliagastrica to pernicious anemia.American Journal of the MedicalSciences 1929, 178:748-763

George H Whipple

M I L E S TO N E S

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of 300 grams of lean beef stimulated hematopoiesis in patientswith pernicious anemia. Administration of gastric juice recoveredfrom histamine-stimulated normal donors was ineffective.Administration of beef digested with pepsin was ineffective.Apparently, there was requirement for interaction between a factorin normal gastric juice and a factor in digested beef. The activitypresent in beef was designated as extrinsic factor; the activitypresent in normal gastric juice was designated as intrinsic factor.In retrospect, some of the dietary regimens in the clinical studiesthat led to the cure of pernicious anemia would probably raiseeyebrows in today's Human Subject Committees.

Subsequent chemical analyses showed that extrinsic factorbelonged to the cobalamin family of organometallic compounds.When it was shown that the active cobalamin was vitamin B12,therapy with vitamin B12 became standard treatment forpernicious anemia. Intramuscular treatment with vitamin B12cured patients. To be effective by oral administration, vitamin B12required the presence of normal gastric juice or massive doses ofthe vitamin. Later studies showed that intrinsic factor was avitamin B12-binding protein produced by gastric gland parietalcells. Biochemical studies showed that vitamin B12 played a role inDNA synthesis, hinting at a mechanism that could account for theunderproduction of red blood cell precursors in the bone marrowof patients with pernicious anemia.

Although curative treatment for pernicious anemia had beenobtained, basic research in the area actually increased andpublications continue through today. Uptake of vitamin B12 wasshown to take place in the ileum via a specific mucosal receptorfor the vitamin B12-intrinsic factor complex. New laboratory testswere developed to screen for pernicious anemia to distinguish itfrom other megaloblastic anemias. A great deal of effort wasdirected at understanding the basis for gastric gland atrophy andthe loss of the intrinsic factor-producing parietal cells. Thediscovery of antibodies specific for parietal cells, intrinsic factorand other elements in the vitamin B12-uptake cascade havefostered the concept of pernicious anemia as an autoimmunedisorder. Coming full circuit from the notion of a microbial etiologythat was in vogue at the start of the 20th century and thendiscarded, it is now firmly established that Helicobacter pylori is agastric pathogen that produces factors that are toxic for parietalcells.

Pernicious anemia is another example of a disease where aneffective treatment came before an understanding of theunderlying pathogenic mechanisms. It is another example wherea disease, an experiment of nature, provided a powerful tool forbiomedical discovery. Once the pathogenic mechanisms ofpernicious anemia were understood, they provided critical insightsinto normal physiological processes, as well as the basis of otherdiseases. Minot, Murphy and Whipple worked without the highlyspecific, sensitive and sophisticated tools that are routine intoday's biomedical research, yet they succeeded in making seminaldiscoveries, curing an incredibly complex disease, and launchingthe field of nutritional deficiency anemias.

References

1. Whipple GH, Hooper CW, Robscheit FS: Am J Physiol 1920, 53:2362. Minot GR and Murphy WP: JAMA 1926, 87:4703. Castle WB: Am J Med Sci 1929, 178:748