MLT GlobeHematology: WBC morphology & differential – page 3
109 Hematology MCQs on WBC morphology & differential with answers and explanations.
Which condition is a classic cause of reactive monocytosis?
Chronic infections such as TB, endocarditis and syphilis, recovery from neutropenia and inflammatory disease cause monocytosis. Corticosteroids lower monocyte counts.
A patient starting clozapine is followed with regular absolute neutrophil counts because this drug can cause:
Clozapine can cause sudden, severe neutropenia (agranulocytosis), so ANC monitoring is required. It is a classic example of drug-induced neutropenia.
Which cell normally makes up the largest percentage of leukocytes in adult blood?
In adults neutrophils are about 40–75% of leukocytes and lymphocytes about 20–40%. In young children lymphocytes may predominate.
A healthy woman's blood smear shows about 1–2% eosinophils and less than 1% basophils. These values are:
Normal adult differentials include about 1–5% eosinophils and 0–1% basophils. No abnormality is present.
In a healthy adult, lymphocytes usually make up about what percentage of the white cells?
Lymphocytes form about 20–40% of adult white cells. Neutrophils are about 50–70%, monocytes a few percent and basophils under 1%.
The main function of neutrophils is:
Neutrophils are the first-line phagocytes against bacteria. Antibodies are made by plasma cells, and histamine comes from basophils and mast cells.
Basophil granules are rich in which substances?
Basophil granules contain histamine and heparin, which are released in allergic reactions.
A 'shift to the left' in the differential count means:
A left shift means more young neutrophil forms (bands, metamyelocytes, sometimes myelocytes) in the blood, typically in bacterial infection.
Natural killer (NK) cells are usually identified by which surface marker?
NK cells are CD56-positive (often CD16-positive) and CD3-negative. CD19 marks B cells, CD3 T cells and CD34 immature progenitor cells.
Helper T lymphocytes carry which surface marker?
Helper T cells are CD4-positive. Cytotoxic T cells are CD8-positive, and CD19 and CD20 are B-cell markers.
A white cell slightly larger than a red cell, with a round dense nucleus and a thin rim of sky-blue cytoplasm, is a:
This is the typical small lymphocyte. Monocytes are much larger with folded nuclei, and neutrophils and basophils have lobed nuclei and granules.
The movement of neutrophils out of blood vessels, squeezing between endothelial cells into the tissues, is called:
Diapedesis is the passage of leukocytes through the vessel wall. Chemotaxis is directed movement toward chemical signals, and margination is sticking to the vessel wall.
Which tissue cell is functionally similar to the blood basophil?
Mast cells, like basophils, carry IgE receptors and release histamine. Kupffer cells are liver macrophages derived from monocytes.
A routine manual differential count classifies how many white cells?
A standard manual differential counts 100 white cells so that each cell type can be reported as a percentage.
Under electron microscopy, which leukocyte's specific granules contain a crystalline core?
Eosinophil secondary granules contain a crystalline core of major basic protein surrounded by a matrix, which gives the characteristic orange granules on Romanowsky stain.
Which leukocyte can proliferate and mature in sites outside the bone marrow, such as the thymus and lymph nodes?
Lymphoid progenitors leave the marrow; T cells mature in the thymus and lymphocytes proliferate in lymph nodes and spleen after antigen exposure. Granulocytes and megakaryocytes develop in marrow.
A child with a prolonged whooping cough has a very high lymphocyte count. Which organism is most likely?
Pertussis toxin blocks lymphocyte migration from blood, causing marked lymphocytosis of small mature cells. Most bacterial infections cause neutrophilia.
Charcot–Leyden crystals in the sputum of an asthmatic patient are derived from which cell?
Charcot–Leyden crystals form from galectin-10 in eosinophils, which increase in allergic conditions such as asthma.
Why are people without a spleen at particular risk from Streptococcus pneumoniae?
The spleen's marginal zone B cells and macrophages handle encapsulated organisms. Nuclei are extruded in the marrow; the spleen only removes inclusions (pitting).
Most neutrophils of a healthy person have round bilobed ('pince-nez') nuclei with normal granules. Family members show the same. This is:
Pelger-Huët anomaly is a harmless inherited defect (lamin B receptor) with hyposegmented but normally functioning neutrophils. The acquired look-alike (pseudo-Pelger) occurs in MDS.