Disorders of leucocytes

Laura Blackwood

doi:10.22233/9781910443255.5

British Small Animal Veterinary Association , 67 (2016); https://doi.org/10.22233/9781910443255.5

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Disorders of leucocytes

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Author: Laura Blackwood
From: BSAVA Manual of Canine and Feline Clinical Pathology
Item: Chapter 5, pp 67 - 93
DOI: 10.22233/9781910443255.5
Copyright: © 2016 British Small Animal Veterinary Association
Publication Date: March 2016

Abstract

Leucocytes (white blood cells) include both granulocytes (neutrophils, eosinophils and basophils) and mononuclear cells (monocytes and lymphocytes). Leucocytes are vital for host defence, and for initiation and control of inflammation and immunity. This chapter looks at assessment of leucocytes, granulocytes, mononuclear cells, leukaemias, myelodysplastic syndromes, myelofibrosis and other evaluations of leucocytes. This chapter also includes case examples.

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Figures

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5.1

Haemopoiesis. BFU-E = burst-forming unit – erythroid; CFU-Eo = colony-forming unit – eosinophil; CFU-GM = colony-forming unit – granulocyte–monocyte; CFU-mega = colony-forming unit – megakaryocyte; NK = natural killer cell; RBC = red blood cell; Th = T helper cell; Treg = regulatory T cell. © 2016 British Small Animal Veterinary Association

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5.1 Haemopoiesis. BFU-E = burst-forming unit – erythroid; CFU-Eo = colony-forming unit – eosinophil; CFU-GM = colony-forming unit – granulocyte–monocyte; CFU-mega = colony-forming unit – megakaryocyte; NK = natural killer cell; RBC = red blood cell; Th = T helper cell; Treg = regulatory T cell.

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5.2

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5.2 Granulopoiesis.

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5.3

Neutrophils, characterized by a segmented nucleus with three to five lobes. (a) Normal neutrophil from a dog. (b–d) Band neutrophils, with U-shaped nuclei lacking segmentation. In (c) the band cell is to the left of a poorly preserved segmented neutrophil. (e–f) Hypersegmented neutrophils (feline). There is also pyknotic change. In (f) the neutrophil on the right has a condensed nucleus while the one on the left is hypersegmented; blue Döhle bodies are also evident (arrowed). In both (e) and (f) there is red cell crenation, supporting in vitro change due to an aged sample. These changes make appreciation of toxic change difficult. (g–k) Toxic changes in band and mature neutrophils. In (g) there is nuclear swelling, chromatin clumping, cytoplasmic basophilia and faint granulation. In (h) there is nuclear swelling, cytoplasmic basophilia and a Döhle body (arrowed). In (j) there is a swollen nucleus, with slightly clumped chromatin, and faint vacuolation. In (k) nuclear swelling, chromatin clumping and cytoplasmic basophilia are seen. (l) Degenerate neutrophils, with nuclear swelling, eosinophilia and lysis. Degenerative changes occur in neutrophils in the tissues and these changes are almost never seen in the circulation. (May–Grünwald–Giemsa stain (except (b, l) Rapi-Diff II® stain); original magnification X1000 (except (f, h) X400)) © 2016 British Small Animal Veterinary Association

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5.3 Neutrophils, characterized by a segmented nucleus with three to five lobes. (a) Normal neutrophil from a dog. (b–d) Band neutrophils, with U-shaped nuclei lacking segmentation. In (c) the band cell is to the left of a poorly preserved segmented neutrophil. (e–f) Hypersegmented neutrophils (feline). There is also pyknotic change. In (f) the neutrophil on the right has a condensed nucleus while the one on the left is hypersegmented; blue Döhle bodies are also evident (arrowed). In both (e) and (f) there is red cell crenation, supporting in vitro change due to an aged sample. These changes make appreciation of toxic change difficult. (g–k) Toxic changes in band and mature neutrophils. In (g) there is nuclear swelling, chromatin clumping, cytoplasmic basophilia and faint granulation. In (h) there is nuclear swelling, cytoplasmic basophilia and a Döhle body (arrowed). In (j) there is a swollen nucleus, with slightly clumped chromatin, and faint vacuolation. In (k) nuclear swelling, chromatin clumping and cytoplasmic basophilia are seen. (l) Degenerate neutrophils, with nuclear swelling, eosinophilia and lysis. Degenerative changes occur in neutrophils in the tissues and these changes are almost never seen in the circulation. (May–Grünwald–Giemsa stain (except (b, l) Rapi-Diff II® stain); original magnification X1000 (except (f, h) X400))

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5.4

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5.4 The major neutrophil pools of the body.

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5.6

A leucoerythroblastic blood picture in a dog with immune-mediated haemolytic anaemia. There is red cell agglutination, and most of the red cells that have agglutinated are spherocytes. There is a strongly regenerative red cell response, with reticulocytes and normoblasts, and a similarly regenerative myeloid response, with band neutrophils and also band-like monocytes. (May–Grünwald–Giemsa stain; original magnification X400) © 2016 British Small Animal Veterinary Association

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5.6 A leucoerythroblastic blood picture in a dog with immune-mediated haemolytic anaemia. There is red cell agglutination, and most of the red cells that have agglutinated are spherocytes. There is a strongly regenerative red cell response, with reticulocytes and normoblasts, and a similarly regenerative myeloid response, with band neutrophils and also band-like monocytes. (May–Grünwald–Giemsa stain; original magnification X400)

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5.9

Eosinophils have a segmented nucleus with only two or three lobes, and coarse eosinophilic cytoplasmic granules. (a–c) Canine eosinophils have widely varying numbers of round variably sized granules. (d–e) Feline eosinophils have small orange–pink granules, which are very numerous and uniform. (May–Grünwald–Giemsa stain; original magnification X1000) © 2016 British Small Animal Veterinary Association

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5.9 Eosinophils have a segmented nucleus with only two or three lobes, and coarse eosinophilic cytoplasmic granules. (a–c) Canine eosinophils have widely varying numbers of round variably sized granules. (d–e) Feline eosinophils have small orange–pink granules, which are very numerous and uniform. (May–Grünwald–Giemsa stain; original magnification X1000)

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5.11

Basophils. (a) Canine basophil and neutrophil. The basophil (on the right) is larger than the neutrophil and has a long mildly lobulated ribbon-like nucleus. (b) Canine basophil with unevenly scattered dark purplish cytoplasmic granules against a pale grey–blue cytoplasm. (c) Feline basophil, showing much more densely packed oval grey–lavender granules. (May–Grünwald–Giemsa stain; original magnification X1000) © 2016 British Small Animal Veterinary Association

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5.11 Basophils. (a) Canine basophil and neutrophil. The basophil (on the right) is larger than the neutrophil and has a long mildly lobulated ribbon-like nucleus. (b) Canine basophil with unevenly scattered dark purplish cytoplasmic granules against a pale grey–blue cytoplasm. (c) Feline basophil, showing much more densely packed oval grey–lavender granules. (May–Grünwald–Giemsa stain; original magnification X1000)

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5.12

Canine mast cell. This is a round cell with a central round to oval nucleus, partially obscured by the variably sized red to lilac and purple granules in the cytoplasm. (Rapi-Diff II® stain; original magnification X1000) © 2016 British Small Animal Veterinary Association

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5.12 Canine mast cell. This is a round cell with a central round to oval nucleus, partially obscured by the variably sized red to lilac and purple granules in the cytoplasm. (Rapi-Diff II® stain; original magnification X1000)

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5.13

Monocytes. (a–d) The nucleus varies in shape and the chromatin appears reticular or lacy. In (a), the monocyte (left) appears larger than the neutrophil. (e–h) Vacuolation in blood samples is usually an in vitro change but can also reflect increased phagocytic activity. In (h) a medium-sized lymphocyte (left) is beside a monocyte with a band-shaped nucleus with rounded ends. ((a, c, f, g) Rapi-Diff II® stain, (b, d, e, h) May–Grünwald–Giemsa stain; original magnification X1000) © 2016 British Small Animal Veterinary Association

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5.13 Monocytes. (a–d) The nucleus varies in shape and the chromatin appears reticular or lacy. In (a), the monocyte (left) appears larger than the neutrophil. (e–h) Vacuolation in blood samples is usually an in vitro change but can also reflect increased phagocytic activity. In (h) a medium-sized lymphocyte (left) is beside a monocyte with a band-shaped nucleus with rounded ends. ((a, c, f, g) Rapi-Diff II® stain, (b, d, e, h) May–Grünwald–Giemsa stain; original magnification X1000)

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5.15

Lymphocytes. (a) Normal canine small lymphocyte, with very scant blue cytoplasm that appears to extend only partway round the nucleus. (b) Normal feline small lymphocyte, larger than a red blood cell. Note the absence of nucleoli. (c) Rubricyte (nucleated red blood cell). This is NOT lymphoid and is smaller, with an eccentrically placed nucleus and clumped chromatin. (d–f) Medium lymphocytes may be up to about the size of a neutrophil; occasionally the cells contain a few reddish granules. (g) Large reactive lymphocyte with increased amounts of intensely basophilic cytoplasm. (h) Large atypical neoplastic cells from a case of lymphoid leukaemia. (i) Large lymphoid cells showing features of malignancy: cytoplasmic basophilia, coarse nuclear chromatin, prominent nucleoli and nuclear moulding. (May–Grünwald–Giemsa stain; original magnification (a–h) X1000, (i) X400) © 2016 British Small Animal Veterinary Association

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5.15 Lymphocytes. (a) Normal canine small lymphocyte, with very scant blue cytoplasm that appears to extend only partway round the nucleus. (b) Normal feline small lymphocyte, larger than a red blood cell. Note the absence of nucleoli. (c) Rubricyte (nucleated red blood cell). This is NOT lymphoid and is smaller, with an eccentrically placed nucleus and clumped chromatin. (d–f) Medium lymphocytes may be up to about the size of a neutrophil; occasionally the cells contain a few reddish granules. (g) Large reactive lymphocyte with increased amounts of intensely basophilic cytoplasm. (h) Large atypical neoplastic cells from a case of lymphoid leukaemia. (i) Large lymphoid cells showing features of malignancy: cytoplasmic basophilia, coarse nuclear chromatin, prominent nucleoli and nuclear moulding. (May–Grünwald–Giemsa stain; original magnification (a–h) X1000, (i) X400)

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5.18

Bone marrow aspirate from a dog with acute lymphoblastic leukaemia. The marrow has been ablated by tumour cells, and virtually no normal haemopoietic cells are seen. In this field, there are densely packed large neoplastic blast cells. These cells show features of malignancy (stippled chromatin, pleomorphic nucleoli, cytoplasmic basophilia and nuclear moulding). (Wright-Giemsa stain; original magnification X1000) © 2016 British Small Animal Veterinary Association

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5.18 Bone marrow aspirate from a dog with acute lymphoblastic leukaemia. The marrow has been ablated by tumour cells, and virtually no normal haemopoietic cells are seen. In this field, there are densely packed large neoplastic blast cells. These cells show features of malignancy (stippled chromatin, pleomorphic nucleoli, cytoplasmic basophilia and nuclear moulding). (Wright-Giemsa stain; original magnification X1000)

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5.22

Immunophenotyping leukaemia. This is a buffy coat smear, from a dog with leukaemia, stained with anti-CD3 antibodies. The brown staining is a positive result, indicating that this is a tumour of T-cell origin. (Courtesy of E Villiers) © 2016 British Small Animal Veterinary Association

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5.22 Immunophenotyping leukaemia. This is a buffy coat smear, from a dog with leukaemia, stained with anti-CD3 antibodies. The brown staining is a positive result, indicating that this is a tumour of T-cell origin. (Courtesy of E Villiers)

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5.23

(a) A scatter plot obtained from a blood sample from a dog with acute lymphoblastic leukaemia. Cell size is on the x-axis and granularity/complexity on the y-axis. The cells in the red gate are atypical lymphoid cells, those in the blue gate are neutrophils (labelled lymphs and neo, respectively). (b) Histogram showing staining of the lymphoid cells with CD79a. The fluorescence is shown on the x-axis and cell number on the y-axis. The vast majority of the lymphoid cells stain with CD79a, which is conjugated to phycoerythrin (PE +ve), indicating a B-cell leukaemia. © 2016 British Small Animal Veterinary Association

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5.23 (a) A scatter plot obtained from a blood sample from a dog with acute lymphoblastic leukaemia. Cell size is on the x-axis and granularity/complexity on the y-axis. The cells in the red gate are atypical lymphoid cells, those in the blue gate are neutrophils (labelled lymphs and neo, respectively). (b) Histogram showing staining of the lymphoid cells with CD79a. The fluorescence is shown on the x-axis and cell number on the y-axis. The vast majority of the lymphoid cells stain with CD79a, which is conjugated to phycoerythrin (PE +ve), indicating a B-cell leukaemia.