JPC SYSTEMIC PATHOLOGY

HEMOLYMPHATIC SYSTEM

February 2024

H-M04 (NP)

 

Signalment (JPC #A29): 5-week-old Holstein calf

 

HISTORY: This calf was born with a leukocyte count of 17,400/µl (65% PMN). At 2 days of age, 23,200/µl (78% PMN); at 14 days of age, 36,600/ul (87% PMN); at 22 days of age, 54,200/µl (93% PMN); at 25 days of age, the calf had a fever of 106 degrees Fahrenheit (41 degrees Celsius), a leukocyte count of 65,000/µl and was unresponsive to antipyretic therapy. At 35 days of age, the calf died during the night.

 

HISTOPATHOLOGIC DESCRIPTION: 1. Spleen: Diffusely the white pulp is decreased and red pulp is markedly expanded by numerous mature neutrophils, fewer plasma cells, lymphocytes, and macrophages admixed with abundant eosinophilic, beaded material (fibrin) and eosinophilic homogeneous fluid (edema). Multifocally there are circumscribed areas of necrosis characterized by a central area with loss of architecture and replacement with abundant eosinophilic cellular and karyorrhectic debris (necrosis) surrounded by many degenerate and viable neutrophils admixed with abundant fibrin and edema. The splenic capsule is thickened by fibrin and low numbers of neutrophils, lymphocytes, and macrophages. Capsular lymphatics are ectatic (edema).

2. Bone marrow: The bone marrow is mildly hypercellular and precursors of all blood cell lines are represented. Over 50% of the cells present are progenitor/proliferating cells of the myeloid series. The myeloid to erythroid (M:E) ratio is approximately 3:1.

MORPHOLOGIC DIAGNOSIS: 1. Spleen: Splenitis, neutrophilic and necrotizing, diffuse, moderate with marked lymphoid depletion, Holstein, bovine.

2. Bone marrow: Myeloid hyperplasia with increased progenitor cells, diffuse, moderate.

CAUSE: CD11/CD18 glycoprotein deficiency, autosomal recessive inheritance

 

CONDITION: Bovine leukocyte adhesion deficiency (BLAD)

GENERAL DISCUSSION: 

• Leukocyte adhesion deficiency types:
  1. Type I (most common) – deficiency of the β-2 integrins
  2. Type II – defect in fucose metabolism à deficiency in sialyl-Lewis X ligand for selectins on leukocytes à “rolling” and “tethering” hindered
  3. Type III – defect in kindlin-3 mediated activation of β1-, β2-, and β3-type integrins expressed on leukocytes and platelets (Boudreaux, 2011)
• BLAD is an autosomal recessive inherited trait described in Holstein cattle that is characterized by a deficiency of β-2 integrins
• Four classes of leukocyte adhesion receptors: Selectins, integrins, immunoglobulin superfamily and mucin-like glycoproteins
  • Selectins (P, E, & L) bind mucin-like glycoproteins (heparan sulfate) to facilitate rolling and adhesion of leukocytes
  • Integrins are heterodimeric glycoprotein leukocyte receptors that bind molecules of the immunoglobulin superfamily [endothelial adhesion molecules; intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1)] to allow firm adhesion and transmigration of leukocytes
    • Heterodimers – α and β are non-covalently linked polypeptide chains with extracellular domains that bind to various ligands including extracellular matrix glycoproteins, activated complement components and proteins on the surface of other cells; the cytoplasmic domains of the integrins interact with cytoskeletal components vinculin, talin, actin, α-actinin and tropomyosin; there are 8 integrin subunits, 3 of which were defined on the basis of which β subunit were used to for the heterodimers 
    • β1-integrins - Adhesion to extracellular matrix - VLA
    • β2-integrins – CD11a-c/CD18, also called leukocyte function associated antigen-1 (LFA-1) family
      • CD11a/CD18 is LFA-1 and plays an important roll in the adhesion of lymphocytes and other leukocytes
      • CD11b/CD18, also known as CR3 or Mac-1; and CD11c/CD18, also known as p150,95 or CR4; mediated leukocyte attachment to endothelial cells and subsequent extravasation 
      • CD11b/CD18 also functions as a fibrinogen receptor and complement receptor on phagocytic cells binding particles opsonized by a by-product of complement activation [inactivated C3b (iC3b)] fragment
      • CD11d/CD18, also known as αDβ2
    • β3-integrins - Interaction of platelets and neutrophils at sites of inflammation

PATHOGENESIS: 

• In BLAD calves, β2-integrin deficiency is caused by a deficiency in biosynthesis of the β2 subunit (CD18) because of a point mutation (adenine > guanine) resulting in a substitution of glycine for an aspartic acid at position 128 (D128G) of the protein sequence in the gene for CD18; consequently, formation of the complete heterodimeric integrin does not take place
• Animals with leukocyte adhesion deficiency demonstrate abnormalities in most adhesion-dependent functions, including attachment to endothelium, neutrophil aggregation and chemotaxis, phagocytosis and cytotoxicity
• The most striking result of impaired β2-integrin expression is evident in the neutrophil, since expression of Mac-1 (CD11b/CD18) by activated neutrophils is essential for adherence to activated endothelial cells expressing ICAM-1 (CD54); in this defect, random migration and chemotactic responses of neutrophils are significantly diminished
• Macrophages and lymphocytes express other adhesion molecules that allow reasonable movement of these cells into tissue, although BLAD calves show delayed or impaired type IV responses to intradermally injected antigen
• Despite the adhesion deficiency in BLAD cattle, neutrophils are able to infiltrate the lung in a yet undiscovered CD18-independent manner

TYPICAL CLINICAL FINDINGS:

• Calves homozygous for the defect have impaired neutrophil function and are susceptible to mucosal infections
• Recurrent bacterial infections
• Persistent and severe neutrophilia, up to 100,000/ul +/- mild left shift
• Decreased albumin to globulin ratio with a polyclonal gammopathy
• Hypoglycemia
• Pyrexia, anorexia, chronic/recurrent pneumonia, mild enlargement of superficial lymph nodes, ulcerative and granulomatous inflammation of oral mucous membranes, gingivitis, and mild recurrent or chronic diarrhea

• Stunted growth

• Death usually occurs between 2 and 7 months of age; with treatment, animals can survive episodes of pneumonia or fever but eventually succumb to enteric disease

 

TYPICAL GROSS FINDINGS:

• Variable – Depends upon organ/system affected
• Ulcerations of the gingiva, hard palate, tongue and small intestine
• Fibrinous peritonitis often with splenomegaly (due to large numbers of neutrophils present there)
• Lack suppurative inflammation in most peripheral tissue despite despite marked neutrophilia

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Splenitis
• Bone marrow hyperplasia with all cell types represented; increased myeloid-erythroid ratio
• Blood vessels in most organs contain abundant circulating neutrophils, but few extravascular neutrophils are evident except in the lungs

• Systemic kappa AL amyloidosis has been reported in a BLAD calf
• On cytology, neutrophils will exhibit ‘aging’ with nuclear hypersegmentation being common

ADDITIONAL DIAGNOSTIC TESTS:

COMPARATIVE PATHOLOGY:

• Irish setter, Irish red and white setter dogs - canine leukocyte adhesion deficiency (CLAD), canine granulocytopathy; defect in the β2 chain (ITGB2) 

• Transgenic mouse model

References:

1. Durham AC, Boes KM.. Bone Marrow, Blood Cells, and the Lymphoid/Lymphatic System. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022: 830-831. 
2. Boudreaux MK, Spangler EA, Welles EG. Hemostasis. In: Duncan and Prasse's Veterinary Laboratory Medicine Clinical Pathology, 5^th Ed. Ames, IA:John Wiley and Sons, Inc. 2011:119.
3. Gu YC, Bauer TR Jr, Ackermann MR, et al. The genetic immunodeficiency disease, leukocyte adhesion deficiency, in humans, dogs, cattle, and mice. Comp Med. 2004;54(4):363-372.
4. Hanna S, Etzioni A. Leukocyte adhesion deficiencies. Ann NY Acad Sci. 2012;1250(1):50-55.
5. Kumar V, Abbas AK, Aster JC. Disease of the Immune System. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathological Basis of Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2021:241.
6. Kumar V, Abbas AK, Aster JC. Inflammation and repair. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathological Basis of Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2021:77-79.
7. Nagahata H. Bovine leukocyte adhesion deficiency (BLAD): a review. J Vet Med Sci. 2004; 66(12):1475-1482.
8. Valli VEO, Kiupel M, Bienzle D. Hematopoietic System. In: Maxie MG, ed. Jubb, Kennedy, and Palmer's Pathology of Domestic Animals, Vol. 3. St. Louis:MO: Elsevier. 2016:109.

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