White Blood Cells and the Pelger-Huët Anomaly.

As with all organ systems, our immune system is made up of cells. It is comprised of 5 types of white blood cells: neutrophils, eosinophils, basophils, lymphocyte, and monocytes. Each cell serves a specific function within the immune system, as well as an array of other functions.

• Neutrophils respond to chemotaxis, perform phagocytosis or living microorganisms as well as the digestion of dead cells. They also participate in margination (the creation of a border) and adhesion to endothelium tissue in the event of inflammation or infection.
• Eosinophils help regulate the innate and adaptive immune responses, as well as remodeling and repairing of tissues. Additionally, it secretes growth factors and triggers the release of histamine.
• Basophils do some phagocytosis, though not as much as a neutrophil. They degranulate in the case of IgE (an antibody believed to fight some parasites) binding to membrane receptors. Basophils also protect from helminth infections (a parasitic worm), and play a role in various inflammation responses by secreting histamines and serotonin, among enzymes and other hormones.
• Monocytes are the white blood cells responsible for differentiating into macrophages, specialized cells within the reticuloendothelial system (that is, the grouping of all macrophages within the body), dendritic cells, and osteoclasts. Among these cells, monocytes perform a number of functions: phagocytosis, antigen-presentation, and the secretion of cytokines, tumor necrosis and interferon factors.
  • As a subset of monocytes, macrophages perform their own functions. They remove parasites and Howell-Jolly bodies from red blood cells. They carry out phagocytosis, storage of iron as well as supplying that iron to erythroblasts.
• The last leukocyte is lymphocytes. Their function depends on which cell they serve as: B cells, T cells, or natural killer cells.
  • B cells further differentiate into memory B cells and Ig-secreting plasma cells.
  • T cells have a variety of functions revolving around cellular immunity. They can regulate immune responses, influence pathogenic immunity, and provide recognition for antigens.
  • Natural killer cells directly kill virus-infected cells or tumor cells. They also produce cytokines to regulate the immune system (Bain, B., 2017).

The structure of immune cell nuclei is no less versatile than their functions.

• Neutrophil nuclei often consist of multiple lobes (2-5), all connected by a filament. There are a few neutrophils that have non-lobulated nuclei but become lobed after maturation.
• The nucleus of an eosinophil tends to be bilobed, the same as a basophil- though a basophil’s nucleus tends to be obscured by purple or black granules.
• A monocyte’s nucleus has an irregular shape, though still tends to be lobulated.
• Lymphocyte nuclei tend to be circular and take up a large portion of the cell (Prinyakupt, Pluempitiwiriyawej, 2015).

Among these normal types of nuclei, however, is an anomaly called the Pelger-Huët Anomaly. This anomaly’s (henceforth PHA) main trait is that it changes the structure of a nuclei by means of hyposegmentation. It might turn a lobed nucleus into a round or oval shape, or simply remove a few of its lobes but leave it bilobed. If a person is homozygous for PHA, many of their neutrophils will have a rounded nucleus rather than the multilobed nucleus of normal neutrophils. The band connecting the lobes within a nucleus is also affected- it becomes shorter and thicker than a non-PHA band.

• PHA is, at this time, believed to be harmless to those who might express it. One’s longevity and quality of life are seemingly not affected by the condition because affected cells still behave normally.
• Though it is not yet understood what causes PHA, it is often associated with an autosomal mutation. This is however not true in all cases. Studies have also shown that it can be caused by drugs and chemical agents, as well as disorders of the blood (Constantino, B., 2005).

Bain, B. 2017. “Structure and function of red and white blood cells.” Medicine, 45(4). https://www.sciencedirect.com/science/article/pii/S1357303917300257#sec6

Constantino, B. 2005. “Pelger-Huët Anomaly – Morphology, Mechanism, and Significance in the Peripheral Blood Film.” Laboratory Medicine. 36(2). https://web.archive.org/web/20180727173254id_/https://watermark.silverchair.com/labmed36-0103.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAbAwggGsBgkqhkiG9w0BBwagggGdMIIBmQIBADCCAZIGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMTigaUatBnZ7u9ZL_AgEQgIIBY8swpI38unZKfRkXyiteyXHkqG5axjZx-Fb17QWuDIRa4pVILDlqE-kxc8EFJGWH4P4hKxLIGAzeGJPDX4doU7NIXgsjAzaVl9icVkpr4a9dGaNe9O9N-yEcw6rGcdt6x0rke4DnlZTW7iB40GOebTv5p4viQLtgnODethcImHSycTQ72j9c2Dgtw-WazMhtRnrIgNEjtFwdFqUenW6YmVZB73dGneFGAicJEF4FWGJabVoDwPXAIZ-UM4gXh3C5np51it6E5oL3r1Lloe6uQwnHAD-4ta52rNp1N94j5L_UjZMl0jvEkP1vtEuwyPpVuWnZ-25be55ctX6uYZNGHS5_dEWDwcdAMuFW7nF31Y3LqXUmvq-MKcsaH7vw8vsAf9aQQUEPNq5hwvvbjkyGPGdmCssLYUtTvGk1VTT88W1X_DnOQzzLdmemo2S3TwikDk72N91q48BlUiZOGKhNcrISF_s

Prinyakupt, J., Pluempitiwiriyawej, C., 2015. “Segmentation of white blood cells and comparison of cell morphology by linear and naïve Bayes classifiers.” BioMed Eng OnLine. 14(63). https://link.springer.com/article/10.1186/s12938-015-0037-1#citeas