A "left shift" refers to the presence of increased proportions of younger, less well differentiated neutrophils and neutrophil-precursor cells in the blood. This generally reflects early or premature release of myeloid cells from the bone marrow, the site where neutrophils are generated. A severe neutrophilia with left shift is referred to as a leukemoid reaction. The leukocyte alkaline phosphatase (LAP) score, which refers to the amount of alkaline phosphatase per neutrophil, will increase. In a severe infection, toxic granulation changes happen to the neutrophils.

This can resemble Pelger-Huet anomaly.

An increase in the number of white blood cells in circulation is called leukocytosis. This increase is most commonly caused by inflammation. There are four major causes: increase of production in bone marrow, increased release from storage in bone marrow, decreased attachment to veins and arteries, decreased uptake by tissues. Leukocytosis may affect one or more cell lines and can be neutrophilic, eosinophilic, basophilic, monocytosis, or lymphocytosis.

A range of disorders can cause decreases in white blood cells. This type of white blood cell decreased is usually the neutrophil. In this case the decrease may be called neutropenia or granulocytopenia. Less commonly, a decrease in lymphocytes (called lymphocytopenia or lymphopenia) may be seen.

Neutrophilia (also called neutrophil leukocytosis or occasionally neutrocytosis) is leukocytosis of neutrophils, that is, a high number of neutrophil granulocytes in the blood.

Neutrophils (also known as neutrocytes) are the most abundant type of granulocytes and the most abundant (40% to 70%) type of white blood cells in most mammals. They form an essential part of the innate immune system. Their functions vary in different animals.

They are formed from stem cells in the bone marrow. They are short-lived and highly motile, or mobile, as they can enter parts of tissue where other cells/molecules cannot. Neutrophils may be subdivided into segmented neutrophils and banded neutrophils (or bands). They form part of the polymorphonuclear cells family (PMNs) together with basophils and eosinophils.

The name "neutrophil" derives from staining characteristics on hematoxylin and eosin (H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink. Normally, neutrophils contain a nucleus divided into 2–5 lobes.

Neutrophils are a type of phagocyte and are normally found in the bloodstream. During the beginning (acute) phase of inflammation, particularly as a result of bacterial infection, environmental exposure, and some cancers, neutrophils are one of the first-responders of inflammatory cells to migrate towards the site of inflammation. They migrate through the blood vessels, then through tissue, following chemical signals such as Interleukin-8 (IL-8), C5a, fMLP, Leukotriene B4 and HO in a process called chemotaxis. They are the predominant cells in pus, accounting for its whitish/yellowish appearance.

Neutrophils are recruited to the site of injury within minutes following trauma, and are the hallmark of acute inflammation; however, due to some pathogens being indigestible, they can be unable to resolve certain infections without the assistance of other types of immune cells.

Granulocytes are a category of white blood cells characterized by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes (PMN, PML, or PMNL) because of the varying shapes of the nucleus, which is usually lobed into three segments. This distinguishes them from the mononuclear agranulocytes. In common parlance, the term "polymorphonuclear leukocyte" often refers specifically to "neutrophil granulocytes", the most abundant of the granulocytes; the other types (eosinophils, basophils, and mast cells) have lower numbers. Granulocytes are produced via granulopoiesis in the bone marrow.

Morning pseudoneutropenia is a transient reduction in the measured neutrophil count from peripheral samples. This is noticed in some patients who are taking antipsychotic medication. Morning pseudoneutropenia is thought to be due to diurnal variation in the amount of circulating white blood cells and changes in the levels of hematopoietic cytokines and granulocyte colony stimulating factor (GCSF). Antipsychotics may amplify the natural variation in these hematopoietic factors.

Neutropenia is a hematological disorder characterized by an abnormally low number of neutrophils in the blood. Neutrophils usually make up 50-70% of circulating white blood cells and serve as the primary defense against infections. There is some variability in the neutrophil counts depending upon when the sample is taken, where the blood sample is taken from, and the system used by the medical lab for measuring the blood cells, but any significant reduction in function or number below the appropriate range may predispose individuals to infections.

Case reports of such incidences are reported with Clozapine and Risperidone and Aripiprazole.

These case reports suggest that the observed cases of the morning pseudoneutropenia did not proceed to become agranulocytosis which is a significant and dangerous side effect of some of antipsychotics. Hence it was suggested that although the morning neutrophil count may appear low, if the antipsychotic medication were considered efficaceous then white cell counts may be repeated in the afternoon prior to making a decision based only on the morning counts.

A lymphocyte is one of the subtypes of white blood cell in a vertebrate's immune system. Lymphocytes include natural killer cells (Phagocytes) (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte".

In cardiovascular disease, increased white blood cell counts have been shown to indicate a worse prognosis.

There are four types of granulocytes:

- Basophils

- Eosinophils

- Neutrophils

- Mast cells

Their names are derived from their staining characteristics; for example, the most abundant granulocyte is the neutrophil granulocyte, which has neutrally staining cytoplasmic granules.

Atypical infections are the key clinical manifestation of SGD. Within the first few years of life, patients will experience repeated pyogenic infections by species such as "Staphylococcus aureus", "Pseudomonas aeruginosa" or other Enterobacteriaceae, and "Candida albicans". Cutaneous ulcers or abscesses and pneumonia and chronic lung disease are common. Patients may also develop sepsis, mastoiditis, otitis media, and lymphadenopathy. Infants may present with vomiting, diarrhea, and failure to thrive.

Diagnosis can be made based upon CEBPE gene mutation or a pathognomonic finding of a blood smear showing lack of specific granules. Neutrophils and eosinophils will contain hyposegmented nuclei (a pseudo-Pelger–Huet anomaly).

Left shift or blood shift is an increase in the number of immature leukocytes in the peripheral blood, particularly neutrophil band cells.

Less commonly, left shift may also refer to a similar phenomenon in severe anemia, when reticulocytes and immature erythrocyte precursors appear in the peripheral circulation.

An increase in eosinophil granulocyte is known as eosinophilia.

Granulocytosis can be a feature of a number of diseases:

- Infection, especially bacterial

- Malignancy, most notably leukemia (it is the main feature of chronic myelogenous leukemia, CML)

- Autoimmune disease

The standard definition of a left shift is an absolute band form count greater than 700/microL. There are competing explanations for the origin of the phrase "left shift," including the left-most button arrangement of early cell sorting machines and a 1920s publication by Josef Arneth, containing a graph in which immature neutrophils, with fewer segments, shifted the median left.

Signs and symptoms of neutropenia include fever, painful swallowing, gingival pain, skin abscesses, and otitis. These symptoms may exist because individuals with neutropenia often have infection

Children may show signs of irritability, and poor feeding. Additionally, hypotension has also been observed in individuals who suffer from this condition

The three major types of lymphocyte are T cells, B cells and natural killer (NK) cells. Lymphocytes can be identified by their large nucleus.

Neutropenia or neutropaenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria, bacterial fragments and immunoglobulin-bound viruses in the blood. Patients with neutropenia are more susceptible to bacterial infections and, without prompt medical attention, the condition may become life-threatening (neutropenic sepsis).

Neutropenia can be acute (temporary) or chronic (long lasting). The term is sometimes used interchangeably with "leukopenia" ("deficit in the number of white blood cells").

Neutrophil-specific granule deficiency (SGD, previously known as lactoferrin deficiency) is a rare congenital immunodeficiency characterized by an increased risk for pyogenic infections due to defective production of specific granules and gelatinase granules in patient neutrophils.

LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia.

Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

Low white cell count may be due to acute viral infections, such as a cold or influenza. It has been associated with chemotherapy, radiation therapy, myelofibrosis, aplastic anemia (failure of white cell, red cell and platelet production), stem cell transplant, bone marrow transplant, HIV, AIDS, and steroid use.

Other causes of low white blood cell count include systemic lupus erythematosus, Hodgkin's lymphoma, some types of cancer, typhoid, malaria, tuberculosis, dengue, rickettsial infections, enlargement of the spleen, folate deficiencies, psittacosis, sepsis, Sjögren's syndrome and Lyme disease. It has also been shown to be caused by deficiency in certain minerals, such as copper and zinc.

Pseudoleukopenia can develop upon the onset of infection. The leukocytes (predominately neutrophils, responding to injury first) start migrating toward the site of infection, where they can be scanned. Their migration causes bone marrow to produce more WBCs to combat infection as well as to restore the leukocytes in circulation, but as the blood sample is taken upon the onset of infection, it contains low amount of WBCs, which is why it is termed "pseudoleukopenia".

Agranulocytosis, also known as agranulosis or granulopenia, is an acute condition involving a severe and dangerous leukopenia (lowered white blood cell count), most commonly of neutrophils causing a neutropenia in the circulating blood. It is a severe lack of one major class of infection-fighting white blood cells. People with this condition are at very high risk of serious infections due to their suppressed immune system.

In agranulocytosis, the concentration of granulocytes (a major class of white blood cells that includes neutrophils, basophils, and eosinophils) drops below 500 cells/mm³ of blood.

A hypersegmented neutrophil is a clinical laboratory finding. It is visualized by drawing blood from a patient and viewing the blood smeared on a slide under a microscope. Normally, the number of segments in the nucleus of a neutrophil increases as it matures and ages after the neutrophil is released into the blood from the bone marrow. Although normal neutrophils only contain three or four nuclear lobes (the "segments"), hypersegmented neutrophils contain six or more lobes.

Hypersegmented neutrophils have classically been thought to be pathognomonic of the class of anemias called megaloblastic anemias (anemias caused by failure of bone marrow blood-forming cells to make DNA, often caused by vitamin B or folate deficiencies, or DNA-replication poisons). However, in seeming contradiction to this, several studies have strongly associated neutrophil hypersegmentation with iron deficiency anemia. In one study 81% of children with iron deficiency had hypersegmented neutrophils, vs. 9% of controls. The mechanism for hypersegmentation in iron deficiency is not yet clear, but has been suggested to be concurrent iron and vitamin deficiency.

One of the earliest, notable changes in the peripheral blood in "megaloblastic processes" is the appearance of hypersegmented neutrophils. Because of the short life-span of neutrophils, these abnormal hypersegmented neutrophils characteristically appear even before the onset of anemia in megaloblastic processes. Such neutrophils are less often seen in the other classes of anemia, which together are far more common than megaloblastic types of anemia. However, as noted, the use of hypersegmented neutrophils to diagnose type of anemia is limited by the fact that different types of nutrient deficiency anemia may coexist.

Note that pernicious anemia is a type of megaloblastic anemia, and as such, is expected to show hypersegmented neutrophils.

Autoimmune neutropenia is a form of neutropenia which is most common in infants and young children where the body identifies the neutrophils as enemies and makes antibody to destroy them.

Primary autoimmune neutropenia (AIN) is an autoimmune disease first reported in 1975 that primarily occurs in infancy. In autoimmune neutropenia, the immune system produces autoantibodies directed against the neutrophilic protein antigens in white blood cells known as granulocytic neutrophils (granulocytes, segmented neutrophils, segs, polysegmented neutrophils, polys). These antibodies destroy granulocytic neutrophils. Consequently, patients with autoimmune neutropenia have low levels of granulocytic neutrophilic white blood cells causing a condition of neutropenia. Neutropenia causes an increased risk of infection from organisms that the body could normally fight easily.

Who is Affected?

Primary autoimmune neutropenia has been reported as early as the second month of life although most cases are diagnosed in children between 5 and 15 months of age. Girls have a slightly higher risk of developing AIN than boys. In neutropenia discovered at birth or shortly after birth, a diagnosis of allo-immune neutropenia (from maternal white blood cell antibodies passively transferred to the infant) is more likely.

Neutropenia

In infants neutropenia is defined by absolute neutrophil counts less than 1000/uL. After the first year of life neutropenia is defined by absolute counts less than 1500/uL. Neutropenia may be primary in which it is the only blood abnormality seen. In secondary neutropenia, other primary conditions occur, including other autoimmune diseases, infections, and malignancies. Neutropenia is considered chronic when it persists for more than 6 months.

Symptoms and Disease Course

Neutropenia, which may be discovered on routine blood tests, typically causes benign infections even when the condition is severe. Ear infections (otitis media) are the most common infection seen in autoimmune neutropenia and typically infection responds to antibiotic treatment alone. Infections associated with primary AIN are usually mild and limited, including skin infections such as impetigo, gastroenteritis, upper respiratory tract infections, and ear infections. Rarely, cellulitis and abscesses may occur.

Studies of children studied for up to six years showed that most cases of autoimmune neutropenia resolved spontaneously after a median of 17 months. In 80 percent of patients, neutropenia persisted for 7 to 24 months.

Diagnosis

Patients with autoimmune neutropenia are diagnosed on the basis of blood tests showing neutropenia and the presence of granulocyte-specific antibodies. In some cases, tests for granulocyte-specific antibodies need to be repeated several times before a positive result is seen. Bone marrow aspiration, if performed, is typically normal or it can show increased cell production with a variably diminished number of segmented granulocytes.

s association with prior parvovirus B19 has been made, but this hasn’t been confirmed. Similar to the platelet deficiency idiopathic thrombocytopenic purpura, vaccines are suspected of triggering this disorder.

Treatment

Treatment consists of corticosteroids to reduce autoantibody production, antibiotics to prevent infection and granulocyte colony-stimulating factor (G-CSF) to temporarily increase neutrophil counts. In cases of severe infection or the need for surgery, intravenous immunoglobulin therapy may be used.

When adhered to a surface, neutrophil granulocytes have an average diameter of 12–15 micrometers (µm) in peripheral blood smears. In suspension, human neutrophils have an average diameter of 8.85 µm.

With the eosinophil and the basophil, they form the class of "polymorphonuclear cells", named for the nucleus' multilobulated shape (as compared to lymphocytes and monocytes, the other types of white cells). The nucleus has a characteristic lobed appearance, the separate lobes connected by chromatin. The nucleolus disappears as the neutrophil matures, which is something that happens in only a few other types of nucleated cells. In the cytoplasm, the Golgi apparatus is small, mitochondria and ribosomes are sparse, and the rough endoplasmic reticulum is absent. The cytoplasm also contains about 200 granules, of which a third are azurophilic.

Neutrophils are sexually dimorphic. Neutrophils from women exhibit a small additional X chromosome structure, known as a "neutrophil drumstick".

Neutrophils will show increasing segmentation (many segments of nucleus) as they mature. A normal neutrophil should have 3–5 segments. Hypersegmentation is not normal, and occurs in some disorders, most notably vitamin B deficiency. This is noted on a manual review of the blood smear, and is positive when most or all of the neutrophils have 5 or more segments.

Neutrophils are the most abundant white blood cells in humans (approximately 10 are produced daily); they account for approximately 50–70% of all white blood cells (leukocytes). The stated normal range for human blood counts varies between laboratories, but a neutrophil count of 2.5–7.5 x 10/L is a standard normal range. People of African and Middle Eastern descent may have lower counts, which are still normal. A report may divide neutrophils into segmented neutrophils and bands.

When circulating in the bloodstream and inactivated, neutrophils are spherical. Once activated, they change shape and become more amorphous or amoeba-like and can extend pseudopods as they hunt for antigens.

Neutrophils have a preference to engulf refined carbohydrates (from ingested glucose, fructose, sucrose, honey and orange juice) over bacteria. In 1973 Sanchez et al. found that the neutrophil phagocytic capacity to engulf bacteria is affected when simple sugars are digested, and that fasting strengthens the neutrophils' phagocytic capacity to engulf bacteria. However, the digestion of normal starches has no effect. It was concluded that the function, and not the number, of phagocytes in engulfing bacteria was altered by the ingestion of sugars. In 2007 researchers at the Whitehead Institute of Biomedical Research found that given a selection of sugars, neutrophils engulf some types of sugar preferentially.

Sweet described a disease with four features: fever; leukocytosis; acute, tender, red plaques; and a dermal infiltrate of neutrophils. This led to the name acute febrile neutrophilic dermatosis. Larger series of patients showed that fever and neutrophilia are not consistently present. The diagnosis is based on the two constant features, a typical eruption and the characteristic histologic features; thus the eponym "Sweet's syndrome" is used.