- Anisocytosis: this is a variation in size of RBCs; it may be an indication of anemia
- Macrocytosis: large RBCs that may be due to a vitamin B12 or folate deficiency. They are seen in megaloblastic anemia (e.g., pernicious anemia), chronic alcoholism, and myelodysplastic syndrome.
- Microcytosis: this is the presence of small RBCs that may be due to an iron deficiency anemia or to an inherited disorder such as thalassemia.
SHAPE -- Poikilocytosis is a variation in the shape of an RBC and may include several different abnormalities at the same time.
- Acanthrocytes (spur, thorn or spiculated cells): irregular shaped cells with 5-10 spicules; may be present in the blood of people who have had their spleen removed (splenectomy) and with, for example, chronic alcoholism (cirrhosis), hemolytic anemia, or thalassemia. They are also present in an inherited disorder called abetalipoproteineimia.
- Echinocytes (burr, crenated or berry cells): may have 10-30 blunt projections and often seen in people with renal failure; may be an artifact – something caused during sample preparation.
- Elliptocytes (ovalocyte): elliptical-shaped RBC seen in hereditary elliptocytosis and various anemias, myelofibrosis.
- Fragmented cells (Schistocytes, Keratocyte, Helmet cell): fragmented RBC of various shapes that may be seen in people with disseminated intravascular coagulation (DIC) or a vascular artificial device (prosthesis) such as a heart valve.
- Rouleaux: RBCs that appear as a stack of coins and seen in people with multiple myeloma or Waldenstrom macroglobulinemia.
- Sickle cells: crescent-shaped RBCs that are characteristic of sickle cell anemia.
- Target cells (leptocytes or codocytes): RBCs that resemble a bull's-eye; commonly seen in people with abnormal inherited forms of hemoglobin (hemoglobinopathies), thalassemia, and various anemias.
- Teardrop cells (dacrocytes): RBCs that resemble a teardrop; often seen in people with myelofibrosis and thalassemia.
- Spherocytosis: sphere-shaped RBCs that are often present in hereditary spherocytosis or due to an immune hemolytic anemia.
- Hypochromasia: this may be seen in a variety of disorders including thalassemia and iron deficiency. The RBC is pale in color due to insufficient hemoglobin and contains a large, hollow middle (central pallor) of the cell.
- Hyperchromasia: the RBC is darker in color than normal; this may be due to dehydration or presence of spherocytes.
- Polychromasia: blue-staining RBCs, indicating that they are immature due to early release from the bone marrow.
Intracellular Structure (nuclear material, remnants, and inclusions inside the RBC)
- Nucleated RBCs (NRBC, normoblasts): a very immature form of RBCs seen when there is a severe demand for RBCs to be released by the bone marrow or marrow involvement by fibrosis or tumor; may be seen in severe anemia, myelofibrosis, thalassemia, miliary tuberculosis, cancers that involve the bone marrow, and in chronic low oxygen levels (hypoxemia). Nucleated RBCs can be normal in infants for a short time after birth.
- Reticulocytes: these are immature RBCs that are usually a blue-staining (polychromatic) color. A few of these young red blood cells are normal in the circulation. Elevated numbers may be seen with acute blood loss, hypoxia, RBC destruction, sickle cell disease, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and autoimmune hemolytic anemia.
- Siderocyte, sideroblast, ring sideroblast: When RBCs are stained with Prussian blue dye, iron granules may be seen. Sideroblasts are immature siderocytes and may actually form a ring pattern indicative of sideroblastic anemia.
- Basophilic stippling is dark blue dots inside the RBC; due to abnormal aggregation of ribosomes and polyribosomes and may be present in heavy metal poisoning (such as lead), nutritional deficiencies, or myelofibrosis.
- Heinz bodies: large inclusion bodies (granules) in the RBCs when stained with crystal violet; may be due to an enzyme (G6PD) deficiency, unstable hemoglobin variant, thalassemia, and autoimmune hemolytic anemia.
- Howell-Jolly bodies (small, round remnants of nuclear DNA inside cell): present in sickle cell anemia, hemolytic or megaloblastic anemias, and may be seen after a splenectomy.
- Cabot's Rings: threadlike inclusions that form a ring within the RBC; may be seen in a variety of anemias.
- Malarial parasites: in people with malaria, these parasites live inside RBCs and may be visible on a blood smear. This is not a routine finding; these parasites are usually found in those who live in or have traveled to areas where the disease is endemic.
NEUTROPHILS (also called segmented neutrophils, segs, polymorphonuclear cells, polys, or PMNs) are about 12 microns in diameter and their function is to engulf and destroy invading organisms. They make up about 50-70% of the total WBC count in the blood and may have two to five nuclear lobes connected by a thin strand of nuclear material. This type of WBC may be seen in greater numbers during infections, malignancies, or extreme stress situations. The cytoplasm of neutrophils is pale and often contains small pink to purple granules. These granules (specific granules and azurophilic granules) contain certain enzymes and proteins that neutralize or destroy microorganisms. Bands are immature neutrophils with a U-shaped nucleus. A small percentage of bands is normal in the blood.
Anomalies of neutrophils may include:
- Toxic Granulation: large dark blue granules in the cytoplasm, associated with severe infection, tissue necrosis, chemical poisoning, and other toxic states.
- Vacuolization: vacuoles appear as holes in the cytoplasm and are frequently found in association with toxic granulation.
- Döhle bodies: irregular grayish or bluish inclusions in the peripheral cytoplasm of neutrophils; they are denatured aggregates of free ribosomes or rough endoplasmic reticulum that are often seen in association with toxic granules and vacuoles. They may be present in association with burns, trauma, acute or systemic infections, and may be present with exposure to cytotoxic agents (i.e., chemotherapy). They may also be seen after cytokine stimulation (e.g., G-CSF) or during a normal pregnancy.
- Auer Bodies (Auer Rods): unique, pink or red rod-shaped inclusions that are seen in very immature granulocytes ("blasts") in people with acute non-lymphocytic leukemias (i.e., acute myeloid leukemia; AML).
- Bands - increased numbers: immature neutrophils are normal in the circulation in small numbers, but if there is a percentage increase of them, there is said to be a "left shift." This may happen when an acute infection stimulates increased neutrophil production, causing the bone marrow to prematurely release some WBCs before they have matured to the neutrophil stage. Other immature forms that may sometimes be seen on a blood smear include myelocyte and metamyelocyte or even promyelocyte and myeloblast.
- Hypersegmentation: neutrophils with six or more nuclear segments; this is mainly associated with vitamin B12 and folate deficiency and myelodysplasia.
- Pelger-Huët: hereditary anomaly where neutrophils appear with fewer than two lobes; the nucleus is often in the shape of a peanut or dumbbell, or may consist of two lobes connected with an obvious filament. They may also appear in certain disease states such as myelodysplasia and is referred to a "pseudo- Pelger-Huët".
- Alder-Reilly granules: large, dark leukocyte granules that stain purple; they are indicative of mucopolysaccharidosis (an inherited enzyme deficiency disorder, Hurler's and Hunter's syndromes).
- Chédiak-Higashi granules: an inherited anomaly characterized by the presence of big red, blue, or greenish granules of variable size that are peroxidase positive and indicate a lethal metabolic disorder, they may be found in granulocytes, lymphocytes, and monocytes. People with this syndrome may exhibit neurological problems as well as a compromised immune system and photophobia. Death often ensues.
BASOPHILS have a multi-lobed nucleus and have many dark blue granules (which contain histamines) in their cytoplasm. Only about 1% of WBCs are basophils. A sight elevation in number may be seen during an allergic response, ulcerative colitis, chronic sinusitis, chickenpox, or immunizations. A significant increase is not uncommon in certain myeloid leukemias.
LYMPHOCYTES are relatively small (7-10 µm) and round in shape. The nucleus is generally large in relation to the amount of cytoplasm. The cytoplasm is pale blue and generally does not contain any granules. The nucleus of most lymphocytes is smooth in appearance and is dark blue. There are two major types of lymphocytes, B cell and T cell, but they cannot be distinguished when viewed under the microscope using standard staining techniques. B cells can be differentiated from T cells using specific fluorescent-labeled antibody stains in conjunction with a special instrument called a flow cytometer. B cells create specific antibodies while T cells can activate B cells as well as recognize and destroy invading organisms. Lymphocytes make up about 20% to 40% of the total WBC count.
- Reactive Lymphocyte (atypical lymphocyte, activated, Downey cells): these cells are large lymphocytes that contain a greater amount of cytoplasm and can vary in size and shape. Often a characteristic bluish tinge of cytoplasm is seen where the cell abuts with surrounding RBCs. Increased numbers of atypical lymphocytes are found in viral illnesses such as infectious mononucleosis.
- Hairy Cells: these lymphocytes have tiny projections that make them appear hairy under the microscope; they are found in hairy cell leukemia.
MONOCYTES are the largest in size of the WBCs and comprise less than 6% in normal blood. They are characterized by their abundant blue-grey cytoplasm that is irregular in shape and have a folded nucleus. The main function of monocytes is to ingest microorganisms and respond to infection and inflammation by releasing certain proteins (monokines) that can inactivate bacteria. When stimulated by cytokines, monocytes can move out of the bloodstream and become tissue macrophages.
- 红细胞大小不均一症：红细胞体积大小不同，存在有小红细胞（<7µm 被称为小红细胞症，大于7 µ m为大红细胞症）。
- 异型红细胞症： 红细胞形态不同，包括棘红细胞、卵圆红细胞、聚集红细胞、角形红细胞、镰刀形细胞、靶形细胞、泪滴样细胞等。
- 嗜酸性粒细胞：在染色后的涂片中非常容易识别，体积大、红橙色颗粒，一般数量较少 (1-3%), 过敏或寄生虫感染患者常见升高。
- 嗜碱性粒细胞：均有大的、黑色颗粒，是白细胞中最不容易看到的类型 (1%)。嗜碱性粒细胞升高并不常见，只有在特定的白血病、鸡痘、溃疡性结肠炎或免疫之后才能见到嗜碱性粒细胞升高。
- 单核细胞：一般是白细胞中最大的一类(12-20 µm)，常常被认为是清除细胞 (吞噬细胞)，它们可以消化细胞碎片、细菌、或其它难溶性颗粒
- 淋巴细胞：淋巴细胞是体积最小的白细胞(10-12 µm) ，具有均一的细胞浆和光滑的圆形细胞核。这些细胞负责产生抗体 (免疫球蛋白)。