Introduction
Howell-Jolly bodies are nuclear remnants found within red blood cells, named after the pioneering work of William Howell and Justin Jolly in the late 19th and early 20th centuries. These bodies are typically extruded during the final stages of erythropoiesis in the bone marrow but can persist in the peripheral blood under certain pathological conditions, particularly when the spleen is absent or functionally impaired. Howell-Jolly bodies may persist in patients with spleen impairment because one of the spleen's functions is to filter deranged blood cells and remove the intracellular inclusions left by the erythrocyte precursors (seeImage.Howell-JollyBody). Identifying and studying Howell-Jolly bodies have provided significant insights into both normal and abnormal erythropoiesis and arecrucial in diagnosing various hematological disorders.[1]
Issues of Concern
Howell-Jolly bodies appear in peripheral blood smears in patients with absent or deficient spleen function. Moreover,Howell-Jolly bodies are pathognomonic for splenic dysfunction but can also be found in several conditions, including:
Splenectomy
Sepsis
Severe hemolytic anemia
Megaloblastic anemia
Congenital disorders
Congenital asplenia
Functional asplenia and sickle cell hemoglobinopathies
Alcoholism
Lupus and other autoimmune disorders
Bone marrow disorders, such as myelodysplastic syndromes or bone marrow infiltration by malignancies, disrupt normal erythropoiesis
Posttransplantation of bone marrow
Severe postpartum hemorrhage
Chemotherapy and radiation therapy
Hereditary spherocytosis
Conditions less commonly associated withHowell-Jolly bodies include:
Gastrointestinal diseases, such as celiac and inflammatory bowel diseases
Neoplastic disorders
Splenic vascular thrombosis
Amyloidosis, elderly
Postmethyldopa treatment
High-dose corticosteroid treatment[2][3][4][5][6][7][8]
Detection and the number of Howell-Jolly bodies do not reflect an accurate assessment of spleen function; however, Howell-Jolly bodies often present concurrently with spleen dysfunction.[9]Other erythrocyte inclusions that should be distinguished from Howell-Jolly bodies include:
Basophilic stippling
Pappenheimer bodies
Heinz bodies
Howell-Jolly body–like inclusions in neutrophils
Howell-Jolly body–like inclusions in COVID-19(Please refer to the Clinical Significancesection for more information)
Structure
Howell-Jolly bodies are DNA-containing inclusions found in red blood cells after erythrocyte maturation. The exact composition of the DNA remains unknown. However, studies show that these inclusions are of centromeric origin. Smaller Howell-Jolly bodies contain nuclear material from 1 to 2 centromeres, whereas larger Howell-Jolly bodies have nuclear fragments from up to 8 centromeres. The most frequently observed fragments are centromeres from chromosomes 1, 5, 7, 8, and 18. The average size of Howell-Jolly bodies is 0.73 µm.[10]
Function
Howell-Jolly bodies are not functional structures but rather cellular remnants that serve as diagnostic markers, as their presence in the peripheral blood indicates certain pathological conditions primarily related to spleen function.Howell-Jolly bodies are observed in patients with asplenia or splenic dysfunctions and in conditions with ineffective erythropoiesis, such as megaloblastic anemia. In this condition, due to vitamin B12 or folate deficiency, the maturation of red blood cells in the bone marrow is impaired, releasing immature red blood cells with nuclear remnants into the bloodstream. Howell-Jolly bodies may also indicate a stressed or recovering bone marrow. During periods of high erythropoietic demand, such as hemolytic crisis or following chemotherapy, immature red blood cells with Howell-Jolly bodies may be released into the circulation before the spleen can remove these remnants.[5][11]
Tissue Preparation
Detecting Howell-Jolly bodies in red blood cells is a critical diagnostic procedure for assessing splenic function and identifying underlying hematological disorders. Proper tissue preparation and staining techniques are essential for accurately identifying these nuclear remnants.
A peripheral blood sample is typically collected using standard venipuncture techniques, with an anticoagulant, such as ethylenediaminetetraacetic acid, to prevent clotting. A small drop of the blood sample is placed on a clean glass microscope slide to prepare the smear. Another slide spreads the drop by placing it at a 30° to 45° angle and smoothly spreads the blood across the slide to create a thin smear. The smear is then allowed to air dry completely, as rapid drying helps preserve cell morphology.
Once dried, the smear is fixed by immersing the slide in methanol for a few minutes, which preserves the cells and prevents further degradation. Howell-Jolly bodies are best visualized using Romanowsky-type stains, including Wright, Giemsa, or a combination of Wright-Giemsa stains. For the Wright-Giemsa stain procedure, the fixed slide is dipped into a jar of Wright-Giemsa stain for about 1 to 3 min, then gently rinsed with distilled water or buffer solution to remove excess stain, and air dried before microscopic examination. Alternative staining methods include the Feulgen reaction, a DNA-specific stain involving hydrolyzing the slide in hydrochloric acid and then staining with Schiff's reagent, and the May-Grünwald stain, another Romanowsky-type stain used similarly to Wright-Giemsa.
The stained blood smear is examined under a light microscope at high magnification, usually with a 100× oil immersion magnification. Howell-Jolly bodies appear as small, round, dark-purple inclusions within the red blood cells, typically singular and located eccentrically within the cell. The findings are documented by taking photomicrographs of representative fields and recording the number of Howell-Jolly bodies per a specified number of red blood cells to quantify their presence.To ensure the staining and detection process is functioning correctly, include slides with known Howell-Jolly bodies as positive controls and use slides without Howell-Jolly bodies as negative controls to confirm the specificity of the staining. If the initial results are ambiguous, prepare and stain additional smears to confirm the presence of Howell-Jolly bodies.[5]
Histochemistry and Cytochemistry
No specific histochemical markers for detecting Howell-Jolly bodies have been established. However, recent advances have been made in detecting and quantifying erythrocyte chromosomal fragments using flow cytometry. Sample preparation uses an RNase/antibody solution and anti-CD71 fluorescein isothiocyanate to detect young reticulocytes. However, this process is not standard in medical practice.[12]
Microscopy, Light
Howell-Jolly bodies appear as small, round, or oval, strongly basophilic (dark purple) inclusions within red blood cells when stained with Romanowsky-type stains, such as Wright or Giemsa. These inclusions are typically singular, located eccentrically within the red blood cell, and vary in diameter. Using the Wright-Giemsa stain, Howell-Jolly bodies appear dark purple due to their high affinity for basic dyes, which bind to the DNA material within the inclusions. This contrast makes Howell-Jolly bodies distinct from other cytoplasmic components. Howell-Jolly bodies are generally found at the periphery of the red blood cell, although they can sometimes be located more centrally.These bodies can be confused with overlapping platelets but do not have the halo that typically overlies platelets.[13]
Microscopy, Electron
Although performing electron microscopy is not routine for examining peripheral blood smears, electron microscopy provides unparalleled resolution and detail in studying cellular structures, making it an invaluable tool for detecting Howell-Jolly bodies in red blood cells.The high resolution of electron microscopy, up to the nanometer scale, allows for detailed visualization of Howell-Jolly bodies within erythrocytes. This level of detail can differentiate between Howell-Jolly bodies and other cellular inclusions or artifacts. In addition, electron microscopy can provide detailed images of the subcellular organization of HJBs, including chromatin arrangement within the nuclear remnants.
Electron microscopy also distinguishes Howell-Jolly bodies from other erythrocyte inclusions, including basophilic stippling, pappenheimer bodies, and Heinz bodies, which is crucial for accurate diagnosis. Advanced electron microscopy techniques, such as scanning electron and transmission electron microscopy, offer three-dimensional reconstructions of erythrocytes, providing a comprehensive understanding of Howell-Jolly bodies' spatial relationships and morphology.Furthermore, electron microscopy can be used for quantitative analysis, such as measuring the size and frequency of Howell-Jolly bodies in a given sample, providing valuable data for clinical assessments. This quantitative capability enhances its utility in evaluating splenic function and related hematological disorders.[14][15][16]
Pathophysiology
Erythrocytes undergo many vital changes and growth to become functional cells for oxygen transportation. Erythropoiesis, the production and maturation of red blood cells, is the process by which new red blood cells are produced. Erythropoiesis is initiated by hematopoietic stem cells in the bone marrow and involves the following stages of maturation:
Proerythroblast: The earliest recognizable precursor in the erythroid lineage is a large cell with a round nucleus and prominent nucleoli.
Basophilic erythroblast: The cytoplasm begins to become basophilic due to ribosomal RNA.
Polychromatic erythroblast: Hemoglobin synthesis starts, and the cell's cytoplasm becomes grayish-blue due to the mix of ribosomes and hemoglobin.
Orthochromatic erythroblast (normoblast): The nucleus becomes smaller and more condensed, eventually extruding from the cell.
Reticulocyte: The cell loses its nucleus and enters the bloodstream. Thereticulocyte still contains some residual RNA and organelles, which are gradually lost asit matures into a fully functional erythrocyte within 1 to 2 days.
The spleen plays a crucial role in maintaining the quality of circulating erythrocytes byremoving defective cells and nuclear remnants through a process known as pitting. In pitting, the red pulp of the spleen contains macrophages that remove inclusions, such as Howell-Jolly bodies, from erythrocytes without destroying the cells themselves. This process ensures that only mature, defect-free erythrocytes remain in circulation.
Howell-Jolly bodies are remnants of nuclear material that are typically removed from erythrocytes during their maturation process in the bone marrow. These remnants appear as small, round, dark-staining inclusions within red blood cells on a peripheral blood smear. In healthy individuals, the spleen effectively removes these nuclear remnants through filtration. The macrophages in the spleen's red pulp identify and extract Howell-Jolly bodies from the erythrocytes, ensuring the removal of defective or immature cells from circulation.[1][17][18]
Clinical Significance
Hyposplenism is associated with several conditions, most commonly including splenectomy; sepsis; congenital disorders, such as congenital asplenia, Ivemark syndrome, Stormorken syndrome, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy [APECED] syndrome, cyanotic heart disease, and prematurity; sickle hemoglobinopathies; alcoholism; lupus; and posttransplantation of bone marrow. Other less common causes are gastrointestinal diseases, such as celiac disease, ulcerative colitis, and Crohn disease; other autoimmune disorders; neoplastic disorders; splenic vascular thrombosis; amyloidosis in older individuals;methyldopa treatment; and high-dose corticosteroid treatment.[3]Splenic dysfunction leaves patients susceptible to infections by encapsulated bacterial organisms, such asStreptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis,because splenic macrophages are responsible for removing encapsulated bacteria. Therefore, these patients should receive prophylactic vaccines, such as pneumococcal and meningococcal.
Historically, nuclear imaging modalities such as spleen scintigraphy have been employed to assess splenic function, but these methods are invasive and time-consuming. Other techniques evaluate the immunological function of the spleen by correlating its volume with spleen-dependent functional B-cell subsets. Indicators such as pitted erythrocytes or Howell-Jolly bodies are useful for scoring splenic function through imaging or spectroscopic approaches. Although Howell-Jolly bodies are sensitive markers for asplenia, they are less effective for detecting mild forms of hyposplenism.Pitted erythrocytes are characterized by depressions on their membranes due to a specific membrane defect, impairing vacuole formation and leading to their pitted appearance.
Although sensitive, detecting pitted erythrocytes requires specialized Nomarski optics-equipped microscopes. Conversely, although less sensitive, detecting Howell-Jolly bodies is feasible with conventional wide-field microscopes, making it a widely used method. Flow cytometry–based techniques for detecting Howell-Jolly bodies–like micronuclei allow measuring large-cell numbers quickly but may face challenges such as insufficient specificity and potential false positives or negatives.
Transferrin-positive reticulocytes are also used to assess splenic function as they represent the youngest erythrocytes in blood, keeping the same stage for typically 2 to 5 h in healthy adults. These reticulocytes have fewer splenic passages, and the frequency of Howell-Jolly bodies intransferrin-positive reticulocytes is much higher compared to mature erythrocytes.[19][20]In addition,current methods for measuring spleen function do not sufficiently address the risk of pneumococcal infection, which is the primary concern associated with spleen impairment in children with sickle cell disease. A complementary method for spleen assessment is necessary, likely involving immunological assays of immunoglobulin M memory B cells and other B-cell subsets, along with anti-pneumococcal antibody titers. Until specific and reliable immunological markers are available and validated, it is suggested that maintaining anti-pneumococcal prophylaxis in children with sickle cell disease until at least 5 years is reasonable, even if Howell-Jolly body counts are normal.[21]
Howell-Jolly bodies are pathognomonic for splenic dysfunction. They are one of many types of inclusions found in circulating erythrocytes, resembling Heinz bodies present in patients with glucose-6-phosphate dehydrogenase deficiency or other hemolytic anemias. Howell-Jolly bodies are also confused with basophilic stippling, a process most attributed to lead toxicity but can occur in conditions including thalassemia, sickle cell disease, vitamin B12 or folate deficiency, and myelodysplastic syndrome. Recent studies have found that Howell-Jolly body–like inclusions in neutrophils and other important immune cells could also be a potential feature to help differentiate between COVID-19 and bacterial pneumonia.[22] Howell-Jolly body–like inclusions occur in immunocompromised states, such as HIV, posttransplant immunosuppression, and chemotherapy.[23]Howell-Jolly bodies must be distinguished from pappenheimer bodies. Pappenheimer bodies are similar to red blood cell inclusions in asplenic patients and are basophilic-staining granules composed of iron compounds, such as ferritin aggregates. Pappenheimer bodies are most common in sideroblastic anemia, myelodysplastic syndrome, and sickle cell disease.[24]Howell-Jolly bodies can interfere with accurately calculating reticulocyte counts, which is essential for evaluating bone marrow erythropoiesis and diagnosing hemolytic anemias.[25]
Figure
Howell-Jolly Bodies. Howell-Jolly bodies appear in peripheral blood smears of patients with absent or impaired spleen function. Contributed by K Humphreys
References
- 1.
Sears DA, Udden MM. Howell-Jolly bodies: a brief historical review. Am J Med Sci. 2012 May;343(5):407-9. [PubMed: 21946828]
- 2.
Ong SY, Ng HJ. Howell-Jolly bodies in systemic amyloidosis. Int J Hematol. 2018 Aug;108(2):119-120. [PubMed: 29790005]
- 3.
William BM, Corazza GR. Hyposplenism: a comprehensive review. Part I: basic concepts and causes. Hematology. 2007 Feb;12(1):1-13. [PubMed: 17364987]
- 4.
Johns J, Goel AK, Jondhale S, Kumar Venkatesan D, Ravina M, Shah S, Syal S. Splenic Dysfunction in Children With Sickle Cell Disease: A Single Centre Experience From Central India. Indian Pediatr. 2024 Jun 20; [PubMed: 38910365]
- 5.
Wagener MG, Marahrens H, Ganter M. Anaemia in South American camelids - an overview of clinical and laboratory diagnostics. Vet Res Commun. 2024 Apr;48(2):633-647. [PMC free article: PMC10998796] [PubMed: 38049672]
- 6.
Narvestad-Bøttger H, Winther-Larsen A, Haugbølle Bjerre J, Dziegiel MH, Hansen AT, Hasle H. Extreme Reticulocytosis After Splenectomy in a Patient With Hemoglobin Mizuho. J Pediatr Hematol Oncol. 2024 Jan 01;46(1):e111-e114. [PubMed: 38011049]
- 7.
Butel-Simoes GI, Jones P, Wood EM, Spelman D, Woolley IJ, Ojaimi S. Congenital asplenia study: clinical and laboratory characterisation of adults with congenital asplenia. Ann Hematol. 2022 Jul;101(7):1421-1434. [PubMed: 35451619]
- 8.
Scott-Charlton A, Reynolds G. A case of systemic lupus erythematosus associated auto-splenectomy presenting as invasive pneumococcal sepsis. Mod Rheumatol Case Rep. 2020 Jul;4(2):233-236. [PubMed: 33087009]
- 9.
de Porto AP, Lammers AJ, Bennink RJ, ten Berge IJ, Speelman P, Hoekstra JB. Assessment of splenic function. Eur J Clin Microbiol Infect Dis. 2010 Dec;29(12):1465-73. [PMC free article: PMC2995208] [PubMed: 20853172]
- 10.
Felka T, Lemke J, Lemke C, Michel S, Liehr T, Claussen U. DNA degradation during maturation of erythrocytes - molecular cytogenetic characterization of Howell-Jolly bodies. Cytogenet Genome Res. 2007;119(1-2):2-8. [PubMed: 18160774]
- 11.
Yan X, Kong J, Wang J, Wang C, Shen H. Severe megaloblastic anemia in a patient with advanced lung adenocarcinoma during treatment with erlotinib: a case report and literature review. BMC Pulm Med. 2024 Mar 06;24(1):121. [PMC free article: PMC10919028] [PubMed: 38448889]
- 12.
Harrod VL, Howard TA, Zimmerman SA, Dertinger SD, Ware RE. Quantitative analysis of Howell-Jolly bodies in children with sickle cell disease. Exp Hematol. 2007 Feb;35(2):179-83. [PubMed: 17258066]
- 13.
Mathew H, Dittus C, Malek A, Negroiu A. Howell-Jolly bodies on peripheral smear leading to the diagnosis of congenital hyposplenism in a patient with septic shock. Clin Case Rep. 2015 Aug;3(8):714-7. [PMC free article: PMC4551333] [PubMed: 26331020]
- 14.
Hilberg RW, Ringle RD, Balcerzak SP. Howell-Jolly bodies. Intracellular or extracellular? Arch Intern Med. 1973 Feb;131(2):236-7. [PubMed: 4682982]
- 15.
JENSEN WN, MORENO GD, BESSIS MC. AN ELECTRON MICROSCOPIC DESCRIPTION OF BASOPHILIC STIPPLING IN RED CELLS. Blood. 1965 Jun;25:933-43. [PubMed: 14294770]
- 16.
RIFKIND RA, DANON D. HEINZ BODY ANEMIA--AN ULTRASTRUCTURAL STUDY. I. HEINZ BODY FORMATION. Blood. 1965 Jun;25:885-96. [PubMed: 14294766]
- 17.
Kashimura M. The human spleen as the center of the blood defense system. Int J Hematol. 2020 Aug;112(2):147-158. [PubMed: 32557229]
- 18.
Nardo-Marino A, Braunstein TH, Petersen J, Brewin JN, Mottelson MN, Williams TN, Kurtzhals JAL, Rees DC, Glenthøj A. Automating Pitted Red Blood Cell Counts Using Deep Neural Network Analysis: A New Method for Measuring Splenic Function in Sickle Cell Anaemia. Front Physiol. 2022;13:859906. [PMC free article: PMC9037235] [PubMed: 35480040]
- 19.
Angay O, Friedrich M, Pinnecker J, Hintzsche H, Stopper H, Hempel K, Heinze KG. Image-based modeling and scoring of Howell-Jolly Bodies in human erythrocytes. Cytometry A. 2018 Mar;93(3):305-313. [PMC free article: PMC5900577] [PubMed: 28544333]
- 20.
Araújo NC, Orlando MMC, Neves MB, Rioja SS, de Lucena SBG, Mandarim-de-Lacerda CA. Howell-Jolly bodies and liver-spleen scanning for assessment of splenic filtrative function yields discordant results in renal transplant recipients. Medicine (Baltimore). 2017 Dec;96(51):e9242. [PMC free article: PMC5758183] [PubMed: 29390481]
- 21.
Pourdieu C, El Hoss S, Le Roux E, Pages J, Koehl B, Missud F, Holvoet L, Ithier G, Benkerrou M, Haouari Z, Da Costa L, El Nemer W, Laurance S, Aronovicz YC, Le Van Kim C, Fenneteau O, Lainey E, Brousse V. Relevance of Howell-Jolly body counts for measuring spleen function in sickle cell disease. Am J Hematol. 2023 May;98(5):E110-E112. [PubMed: 36794434]
- 22.
Oehadian A, Huang I, Kartikasari A, Alisjahbana B, Prihatni D. Howell-Jolly Body-Like Inclusions in Coronavirus Disease 2019 (COVID-19): Possible Novel Findings. J Blood Med. 2023;14:233-238. [PMC free article: PMC10066893] [PubMed: 37016662]
- 23.
Sharma P, Nampoothiri RV, Sharma P, Prakash G, Malhotra P, Varma N. Howell-Jolly Body-Like Inclusions in Neutrophils and Monocytes of a Transplant Recipient. Indian J Hematol Blood Transfus. 2018 Apr;34(2):381-382. [PMC free article: PMC5884985] [PubMed: 29622896]
- 24.
Sears DA, Udden MM. Pappenheimer bodies: a brief historical review. Am J Hematol. 2004 Apr;75(4):249-50. [PubMed: 15054821]
- 25.
van Berkel M, Besselaar E, Kuijper P, Scharnhorst V. Instrument-dependent interference of Howell-Jolly bodies in reticulocyte enumeration. Clin Chem Lab Med. 2013 Jun;51(6):e137-9. [PubMed: 23314550]
Disclosure: Adegbenro Fakoya declares no relevant financial relationships with ineligible companies.
Disclosure: Razie Amraei declares no relevant financial relationships with ineligible companies.
