Eosinophil Information and Courses from MediaLab, Inc.

In the cytospin procedure, use a high speed centrifuge to concentrate the cells on a slide in a uniform monolayer 6 mm in diameter. The monolayer distribution enhances the morphological appearance of the cells present.Allow the slides to dry in air for several minutes and then stain them with Wright-Giemsa stain. Cytospin slides may be placed in an automatic stainer, such as Hema-Tek, or stained manually.Perform a 100 or 200 cell differential and record the number of neutrophils, eosinophils, basophils, lymphocytes, monocytes, macrophages, and blasts cells.Pathologists must review any slide which has tumor cells, unidentified cells, or immature stages of cells, such as blasts.Since criteria for review may vary from one laboratory to another, be sure to check the requirements in your laboratory before reporting the differential.

Granulocytic white blood cells in a urine sample suggest the presence of a urinary tract infection. Granulocytes, which include neutrophils, basophils and eosinophils, contain esterases. These esterases catalyze the strip reagent indoxylcarbonic acid ester to release indoxyl. Indoxyl reacts with a diazonium salt to produce a purple color. The intensity of the color produced is proportional to the amount of enzyme present.

Antibody - A modified type of serum globulin synthesized by lymphoid tissue in response to antigenic stimulus. By virtue of specific combining sites each antibody reacts with only one antigen. Anucleate - Having no nucleus. Azurophilic granules - The well-defined large reddish granules (lysosomes) which may be present in large lymphocytes. They are called "azurophilic granules" because they stain blue with the azure stains which were originally used. Basophilic granules - Specific granules present in the cytoplasm of basophils. These granules are large and stain purple-black due to their strong affinity for basic stain. B-cell - Bone marrow derived lymphocytes which produce humoral antibodies. Biconcave - Having two concave surfaces. Cellular Immunity - The capacity of a small proportion of lymphoid population to exhibit response to a specific antigen. Chromomere - The centrally located granular portion of the platelet. Clone - A population of cells descended from a single cell. Delayed Hypersensitivity - (part of cellular immunity) that develops slowly over a period of 24-72 hours after an antigenic stimulus. It consists of an accumulation of cells around small vessels and/or nerves. Example: Tuberculin skin test reaction. Digestive Enzyme - A substance that catalyzes or accelerates the process of digestion. Eosinophilic Granules - Specific granules present in the cytoplasm of eosinophils. These granules are large, refractile spheres which stain reddish-orange due to their strong affinity for acid stain. Erythrocyte (red blood cell, RBC) - One of the elements found in peripheral blood. Normally the mature form is a non-nucleated, circular, biconcave disk adapted to transport respiratory gases. Fixed Macrophage - A phagocyte that is non-motile. Free Macrophage - An ameboid phagocyte present at the site of inflammation. Graft Rejection - A transplanted tissue that is rejected by the body's antibodies. Graft vs. Host Reaction - A complication that occurs when an implanted piece of tissue, which contains antibodies, rejects the host's tissue. Granulocyte - A leukocyte which contains granules in its cytoplasm, i.e., neutrophilic, eosinophilic, or basophilic granules. Half-life - is the length of time it takes for half of the cells circulating at a given time to leave the blood for the tissues. Hemocyte - Any blood cell or formed element of the blood. Hemostasis - A mechanism of the vascular system to arrest an escape of blood. It involves an interaction between blood vessels, platelets, and coagulation. Heparin - A mucopolysaccharide acid which, when present in sufficient amounts, functions as an anticoagulant by inhibiting thrombin. Histamine - A powerful dilator of capillaries and a stimulator of gastric secretions. Humoral Immunity - Acquired immunity produced after response to an antigenic stimulus in which B cells produce circulating antibodies. Hyalomere - the clear, blue non-granular zone surrounding the chromomere of a platelet. Immune Response - The interaction of a cell and an antigen that results in a proliferation of the cell and a capacity to produce antibodies. Isotonic Fluid - A fluid whose elements have an equal osmotic pressure. Leukocyte (white blood cell, WBC) - One of the formed elements of the blood; involved primarily with the body's defense. Lysosome - A microscopic body within cell cytoplasm; contains various enzymes, mainly hydrolytic, which are released upon injury to the cell. Megakaryocyte - A giant cell of the bone marrow from which platelets are derived. Mononuclear - A cell having a single nucleus.

The chromatin pattern of the basophil nucleus is not quite as coarse as that of the neutrophil or eosinophil nuclei. Although the nucleus is usually segmented, the lobes are often difficult to discern because they tend to crowd together and are obscured by the cytoplasmic granules.

The granulocytes found in normal peripheral blood are neutrophils, eosinophils and basophils.Most have segmented nuclei, and are therefore classified as being at the "segmented" stage of development. Some that are a little less mature have unsegmented nuclei. These are classified as "bands." Generally, we differentiate between the band and segmented forms of neutrophils, but since eosinophils and basophils are present in such low numbers, and since their nuclei are often obscured by cytoplasmic granules, we usually don't concern ourselves with designating the band forms.Since hematologists and textbooks use several different terms for these cells, synonyms for each term will be given and then may be used interchangeably throughout the course.

The color of the cytoplasm is light pink to colorless, but as with eosinophils, the specific basophilic granules are prominent.These granules are large and, because they take up the basic components of Wright-Giemsa stain, are purplish-black.

Eosinophils have a circulating half-life of approximately 18 hours and a tissue life span of at least 6 days.They are capable of locomotion and phagocytosis and can enter inflammatory sites, but do so less readily than neutrophils.In tissues the primary location for eosinophils is in the epithelial barriers to the outside world such as, lungs, skin and GI tract.They are capable of returning to the circulating blood and bone marrow after they enter the tissues.

Basophils serve as mediators of inflammatory responses, especially hypersensitivity reactions.IgE binds to the membrane receptors on basophils and degranulation is initiated.The enzymes released are vasoactive, bronchorestrictive and chemotactic (especially for eosinophils), so basophils seem to play a role in inducing and maintaining allergic reactions.The granules of basophils contain histamine, heparin and peroxidase.After degranulation occurs, basophils can synthesize more granules.The release of large numbers of these granules can cause anaphylactic shock and death.

Patients with hypersensitivity reactions, sometimes as a result of medications, may have eosinophils in their urine. Hansel's stain, which is specific for eosinophils, or Wright-Giemsa stain may be used to distinguish these cells from neutrophils.

May-Hegglin anomaly is an autosomal dominant condition characterized by the presence of pale blue inclusions in neutrophils, giant platelets, and sometimes thrombocytopenia. Inclusions can also occur in eosinophils, basophils, and monocytes. May-Hegglin inclusions resemble Dohle bodies but are larger and more prominent. Acquired forms of this anomaly may also occur as a result of the use of cytotoxic drugs. May-Hegglin bodies seen under these circumstances are considered pathological.

Chediak-Higashi syndrome is a rare autosomal recessive disorder. It results from a mutation of the gene LYST which encodes a protein with multiple phosphorylation sites. This defect causes a cellular abnormality involving the fusion of cytoplasmic granules. Early in neutrophil maturation normal azurophilic granules form, but they fuse together to form megagranules. Later during the myelocyte stage, normal specific granules form. The mature neutrophils contain both normal specific granules and abnormal azurophilic granules. These large abnormal granules can be seen in the cytoplasm of neutrophils, eosinophils, basophils, monocytes and lymphocytes. These abnormal granules are able to kill bacteria in neutrophils and monocytes; however, the process is much less effective than in normal cells in part, because these neutrophils have impaired locomotion. For these reasons, individuals with Chediak-Higashi have recurrent infections. An accelerated lymphoma-like phase occurs, with lymphadenopathy, hepatosplenomegaly, and pancytopenia. Death often occurs at an early age.

The following are suggested guidelines directed toward white blood cell data necessitating a hematologist's review:Total white blood cell count <3000/cumm or >12,000/cummNeutrophils >85%Lymphocytes >43% or <10%Monocytes >8%Eosinophils >6%Basophils >4%,.Mixed cells >8% on a 3-part automated differentialA morphology review may also be indicated if the platelet count is <100,000/cumm or >650,000/cumm.Thus, if the granulated cells illustrated in the photograph exceed 6% of the total WBC on a five-part differential or, in combination with monoctytes and basophils, exceed 8% of the total WBC on a three-part differential, a flag would alert the operator that a morphology review or manual differential is needed.

Illustrated in the upper photograph is a cytoplasmic inclusion somewhat resembling a Doehle body. Note that this inclusion is well defined and there is no evidence of toxic granulation in the cytoplasm. When Doehle-like bodies are identified, May-Hegglin anomaly should be considered in the differential diagnosis even though this entity is rare. The May-Hegglin anomaly is an inherited dominant condition in which large 2 - 5 um, basophilic and pyronophilic inclusions are present in granulocytes, including neutrophils, eosinophils, basophils, and monocytes. Similar to Doehle bodies, the May-Hegglin inclusions also are composed of RNA, probably derived from the rough endoplasmic reticulum. May-Hegglin anomaly includes giant platelets containing few fine granules (lower photograph). Sometimes the platelets have bizarre shapes and variable sizes. Variable degrees of thrombocytopenia complicated by mild bleeding problems and purpura may accompany the aberrant platelets.

The cytoplasm of eosinophils is evenly filled by numerous orange-red granules of uniform size. They do not overlie the nucleus. The eosinophil granules contain numerous enzymes including peroxidase, phospholipase D, catalase, acid phosphatase, and vitamin B12-binding proteins. Their ability to kill bacteria is less than that of neutrophils. Their main purpose is to counteract parasitic infections and to participate in immune allergic reactions. They may also be increased in a variety of nonimmunologic inflammatory responses from bacteria and fungi causing chronic infections. Malignancies, collagen vascular diseases, and myeloproliferative disorders may also may be settings for prominent eosinophils.

An 80 year old man was seen in the emergency room with sudden onset of right sided chest pain accentuated on inspiration. His cough was productive of yellow sputum, and he was short of breath.His temperature was 101.2F. A chest X-ray revealed right middle lobe pneumonia. His hemoglobin was 15.2 gm/dl, HCT 44%, and RBC 4.5 m/ml. The white blood count was 35,000/cuml, with 45% neutrophils, 20% bands, 5% lymphocytes, 3% eosinophils, 2% basophils, and 25% atypical monocytes as noted in the photograph.The atypical monocytes had abundant blue-grey cytoplasm with a few scattered vacuoles, which, in company with toxic neutrophils appeared to be a response to infection.The patient had a past history of tuberculosis which may account for the monocytosis.