Immunology: Eosinophils and Basophils

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Questions and Answers

What is the primary function of eosinophils?

Inflammatory response regulation

Histamine release

Destruction of bacteria

Destruction of parasites (correct)

Which condition is most commonly associated with eosinophilia worldwide?

Parasitic infections (correct)

Idiopathic conditions

Allergic disorders

Neoplastic disorders

In which conditions is isolated basophilia more likely to occur?

Acute allergic reactions

Chronic myelogenous leukemia (correct)

Hematological neoplasms

Severe infections

What is the normal percentage range of monocytes found in a peripheral blood smear?

2% to 9% Signup and view all the answers

What is a major function of monocytes once they migrate to tissues?

Tissue repair Signup and view all the answers

What is a common cause of reactive eosinophilia in developed countries?

Allergic disorders Signup and view all the answers

What component primarily causes the elevation of basophil counts in reactive conditions?

Histamine Signup and view all the answers

Monocytes contain granules in their cytoplasm that are responsible for which activity?

Phagocytosis of microbes Signup and view all the answers

What percentage of circulating white blood cells are neutrophils in adults?

50% to 70% Signup and view all the answers

Which function do neutrophils NOT perform?

Activation of T-lymphocytes Signup and view all the answers

What is the primary characteristic of mature neutrophils compared to myeloid precursors?

More mobile and deformable Signup and view all the answers

What term describes an increase in the absolute number of white blood cells?

Absolute leukocytosis Signup and view all the answers

Which of the following changes occurs in neutrophils in response to chemoattractants?

Increased ameboid movement Signup and view all the answers

Which disorder is associated with lymphocytosis?

Infectious mononucleosis Signup and view all the answers

What effect does the Epstein–Barr virus (EBV) have on lymphocyte populations?

It increases both B- and T-lymphocyte populations. Signup and view all the answers

What morphological feature differentiates infectious mononucleosis from other reactive lymphocytoses?

Presence of atypical lymphocytes Signup and view all the answers

What are the two main pools of mature neutrophils after they leave the marrow?

Marginating and circulating pools Signup and view all the answers

Which process allows marginating neutrophils to enter tissues?

Diapedesis Signup and view all the answers

What is the approximate half-life of circulating neutrophils in the bloodstream?

7 hours Signup and view all the answers

What ultimately happens to neutrophils that remain in tissues and are not used in an inflammatory process?

They die by apoptosis or are destroyed. Signup and view all the answers

Which of the following phases is NOT part of neutrophil phagocytosis?

Transmigration and adherence Signup and view all the answers

What is the term for the random and nondirectional movement of neutrophils along vessel endothelium?

Locomotion Signup and view all the answers

What is the process called that directs neutrophils towards a site of injury using chemical signals?

Chemotaxis Signup and view all the answers

Which mechanism increases the rate of neutrophil migration towards an inflammatory site?

Chemokinesis Signup and view all the answers

What condition can be a secondary cause of neutropenia?

Malignancy of the bone marrow Signup and view all the answers

Which of the following is a characteristic of Chediak-Higashi syndrome?

Presence of giant lysosomal granules Signup and view all the answers

Which of the following defects affects neutrophil motility?

Defects affecting chemotaxis and motility Signup and view all the answers

What is typically observed in a peripheral blood smear of a patient with functional defects of neutrophils?

Generally unremarkable findings Signup and view all the answers

Which deficiency can lead to neutropenia as a secondary condition?

Dietary B12 deficiency Signup and view all the answers

What management is typically required for patients with Chediak-Higashi syndrome during infection?

Prophylactic antimicrobial therapy Signup and view all the answers

What percentage of eosinophils is typically found in normal peripheral blood smears?

2% to 4% Signup and view all the answers

Which of the following is NOT a type of defect that can characterize functional disorders of neutrophils?

Nutritional deficiencies Signup and view all the answers

What is one of the primary roles of proteins secreted by monocytes?

Regulation of hematopoiesis Signup and view all the answers

Which condition is generally associated with reactive monocytosis?

Chronic infection Signup and view all the answers

What defines absolute lymphocytosis?

Increase in the total number of lymphocytes present Signup and view all the answers

How does relative lymphocytosis differ from absolute lymphocytosis?

It indicates a relative percentage increase of lymphocytes. Signup and view all the answers

Which type of lymphocyte is described as benign and transformed?

Reactive lymphocyte Signup and view all the answers

What is NOT a function of monocyte secreted proteins?

Facilitating neuronal repair Signup and view all the answers

Which disorder is not associated with absolute monocytosis?

Chronic lymphocytic leukemia Signup and view all the answers

In adults, what percentage range do lymphocytes comprise of the total WBC count?

20% to 40% Signup and view all the answers

Study Notes

Eosinophils

Eosinophils are white blood cells that contain secondary granules rich in major basic protein.
These granules help to destroy parasites and play a role in immediate hypersensitivity reactions.
Eosinophilia, an increased number of eosinophils, can be caused by neoplastic, reactive, or idiopathic factors.
Parasitic infections are the most common cause worldwide, while allergic disorders are most common in developed countries.

Basophils

Basophils are white blood cells that make up 1% to 2% of peripheral blood.
They are uncommon in isolation but can increase in response to allergy, hypersensitivity, or inflammation.
This is due to histamine, a major component of basophilic granules.
Basophilia can also indicate a malignant process, particularly in myeloproliferative neoplasms, where the count is significantly higher due to elevated white blood cell count.
Chronic myelogenous leukemia (CML) is the most common cause of basophilia.

Monocytes

Monocytes constitute 2% to 9% of peripheral blood.
They function in phagocytosis, antimicrobial activities, tissue repair, and other functions after migrating to tissue.
These cells contain fine granules which contribute to the destruction of microbes.

Neutrophils

Neutrophils are the most numerous leukocytes, accounting for 50% to 70% of circulating white blood cells in adults.
They act as phagocytes capable of ameboid movement into tissues to engulf and destroy bacteria or fungi, making them the first responders to infection.
They also mediate inflammatory processes.
Mature neutrophils are smaller than myeloid precursors, enhancing their mobility and deformability.
Neutrophils exist in two pools: marginating and circulating.
The marginating pool, not measured by peripheral blood sampling, consists of cells adhering to vessel endothelium within the vascular spaces.
They enter tissues by diapedesis in response to inflammation or injury.
Neutrophils in the circulating pool leave the blood by random migration after a half-life of ~7 hours.
These neutrophils do not return to the bloodstream from tissues.
After entering tissues, neutrophils are believed to remain for several days, eventually dying by apoptosis or being destroyed by phagocytic cells.
Neutrophil function during phagocytosis occurs in three phases: migration and diapedesis; opsonization and recognition; and ingestion, killing, and digestion.
Neutrophils in the marginating pool move along vessel endothelium randomly, a process called locomotion.
This movement becomes directional in response to chemoattractants, known as chemotaxis.
Chemoattractants can accelerate neutrophil migration, a phenomenon called chemokinesis.
Neutropenia can be acquired secondary to aplastic anemia, malignancy of the bone marrow, or dietary deficiencies in B12 or folate.
Congenital neutropenias, rare disorders, are characterized by defective or deficient neutrophil production in the bone marrow.
Qualitative neutrophil disorders involve hereditary abnormalities in function, leading to bacterial infections.
Functional defects may be acquired or inherited, classified by their type: phagocytic/killing defects, granule structure and function defects, defects affecting chemotaxis and motility, and adhesion defects.
Chediak–Higashi syndrome, a rare neutrophil disorder, is characterized by recurring bacterial infections, partial albinism, and the presence of giant lysosomal granules in nucleated cells.
Management involves prophylactic antimicrobial therapy and aggressive intravenous treatment during infection.

Lymphocytes

Lymphocytosis indicates an increased number of lymphocytes in the peripheral blood.
In adults, lymphocytes represent 20% to 40% of the relative differential count.
Relative lymphocytosis refers to an increased percentage of lymphocytes in a white blood cell differential.
Absolute lymphocytosis refers to the total number of lymphocytes present.
Reactive lymphocytes are transformed or benign lymphocytes.
Reactive lymphocytes and normal lymphocytes vary in size, shape, and immunophenotypic markers.
Malignant lymphocytes are cancerous lymphocytes.

Monocytes (Continued)

Monocytes secrete proteins that regulate hematopoiesis, stimulate inflammatory reactions, remove infectious organisms, senescent blood cells, and modulates the immune function.
They also stimulate host defense against tumor cells.
Reactive monocytosis is associated with chronic infections, autoimmune diseases, splenectomy, and various malignancies.
Absolute monocytosis is found in malignant hematopoietic disorders such as chronic myelomonocytic leukemia (CMML), chronic myelogenous leukemia (CML), acute monocytic leukemia, and acute myelomonocytic leukemia (AMML).

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Description

This quiz explores the characteristics and functions of eosinophils and basophils, two types of white blood cells. You will learn about their roles in immune responses, associated conditions, and their relevance in allergic and parasitic reactions. Test your knowledge on these immune cells and their importance in health and disease.