Immune Mediated Neutropenia in Man and Animals: A Review

Primary immune-mediated thrombocytopenia and immune-mediated neutropenia suspected in a 21-week-old Maine Coon cat

CASE REPORT

A 21-week-old Maine Coon cat presented with an acute-onset coagulopathy. Severe concurrent thrombocytopenia and neutropenia were identified on peripheral blood smears and bone marrow cytology supported a peripheral consumptive process. Other than mild superficial haemorrhage, the cat was clinically well and screening for retroviral diseases, abdominal ultrasound examination, thoracic radiography, haematology and biochemistry panels did not identify an underlying disease. There was no historical pharmaceutical or toxicological trigger noted and the cat was from an area without endemic Ehrlichia spp. There was a rapid resolution of both cytopenias following treatment with immunosuppressive doses of prednisolone, though a mild relapse occurred during gradual prednisolone withdrawal and was responsive to a dose increase.

CONCLUSIONS

This report describes this combination of diseases for the first time in a cat and presents a younger patient than previously described with feline primary immune-mediated haematological disease.

Multiple Cytopenias Associated with Monocytic Proliferation in a Dog

An unusual combination of blood cytopenias and monocytic proliferation was observed in a dog. Initial hematologic findings included severe thrombocytopenia, neutropenia, mild nonregenerative anemia and apparently normal bone marrow. Subsequently, a severe persistent monocytosis developed and the bone marrow became populated with monocytes and cytophagic macrophages. Splenomegaly was due to reticuloendothelial hyperplasia and extramedultary hematopoiesis. Treatment consisted of splenectomy and azathioprine but the response was poor and the dog was euthanized. Postmortem examination revealed a hypocellular bone marrow which contained moderate numbers of monocytes and plasma cells. Neoplastic proliferation was absent in visceral organs. No definite diagnosis was established; chronic blood cell consumption, perhaps immune-mediated, may have been responsible for the extensive reticuloendothelial hyperplasia and cytophagia.

Evaluation of clinicopathologic features, response to treatment, and risk factors associated with idiopathic neutropenia in dogs: 11 cases (1990–2002)

OBJECTIVE

To evaluate the clinicopathologic features, response to treatment, and risk factors associated with idiopathic neutropenia in dogs.

DESIGN

Retrospective case series.

ANIMALS

11 dogs.

PROCEDURES

Medical records of dogs with idiopathic neutropenia were reviewed. Signalment, history, clinical signs, and response to treatment were recorded and compared with that in dogs with neutropenia attributable to known causes and to dogs without neutropenia (controls).

RESULTS

Compared with dogs with neutropenia attributable to known causes, dogs with idiopathic neutropenia had lower neutrophil counts and were younger. When compared with control dogs, age < 4 years was identified as a risk factor for developing idiopathic neutropenia. In all dogs with idiopathic neutropenia, remission of neutropenia occurred within 18 days after administration of prednisone (2 to 4 mg/kg [0.9 to 1.8 mg/lb], PO, daily) and no serious complications or infections developed.

CONCLUSIONS AND CLINICAL RELEVANCE

An immune-mediated pathogenesis should be considered for dogs with idiopathic neutropenia in which the cause is not known. Severe neutropenia and young age were significantly associated with idiopathic neutropenia in dogs. Prognosis appeared to be excellent with prednisone treatment.

Immune-mediated neutropenia suspected in five dogs

Five cases of suspected immune-mediated neutropenia in dogs are described. Clinical signs varied depending on whether the animals had a systemic infection or concurrent immune-mediated disease. Patients were diagnosed by excluding other causes of neutropenia, supportive bone marrow aspirate findings, an initial favourable response to corticosteroid administration in four of the cases, and concurrent immune-mediated disease. Four of the dogs were receiving medications at the time of diagnosis, and immune-mediated neutropenia secondary to drug therapy cannot be excluded. This study shows that appropriate immunosuppressive treatment can lead to a favourable outcome, however, care is required to avoid adverse effects associated with corticosteroid use. It is also imperative that medications are not withdrawn abruptly as a second remission may not always be achievable.

Immune-mediated neutropenia in 2 dogs

Immune‐mediated neutropenia, also termed autoimmune neutropenia (AIN), is an uncommon event, rarely documented within veterinary literature, although the clinical profile and probable pathogenesis have been outlined in detail within medical literature. In this paper, we review 2 different manifestations of this disorder. The 1st case primarily involved peripheral destruction of mature neutrophils, with little impact on marrow precursors, whereas the 2nd case resulted in suppression of neutrophilic granulopoiesis within marrow. In both cases, absolute neutrophil counts dropped below 200/mL.

Immune-mediated neutropenia in 2 dogs

Immune‐mediated neutropenia, also termed autoimmune neutropenia (AIN), is an uncommon event, rarely documented within veterinary literature, although the clinical profile and probable pathogenesis have been outlined in detail within medical literature. In this paper, we review 2 different manifestations of this disorder. The 1st case primarily involved peripheral destruction of mature neutrophils, with little impact on marrow precursors, whereas the 2nd case resulted in suppression of neutrophilic granulopoiesis within marrow. In both cases, absolute neutrophil counts dropped below 200/mL.

Neutropenia with a probable hereditary basis in Border Collies

This paper documents a disease of Border Collies characterised by chronic neutropenia which probably resulted in recurrent bacterial infections manifesting as osteomyelitis and sometimes gastroenteritis. The neutropenia occurred despite hyperplasia of the myeloid cells in the bone marrow and a shift to the right in myeloid cell maturation. The underlying defect is currently unknown but may result from the inability of neutrophils to escape from the bone marrow into the peripheral circulation. Necrosis and new bone formation commonly involved the metaphyseal regions of long bones. Other findings included a fasting hypercholesterolaemia and the occasional presence of nucleated red blood cells in circulation, despite a non-regenerative anaemia. An autosomal recessive mode of inheritance is suspected. This condition has some features of a rare human disease called myelokathexis which is also believed to have in autosomal recessive mode of inheritance.

Clinical interpretation of leukocyte responses

Basic information has been presented concerning leukocyte (neutrophil, monocyte, lymphocyte, eosinophil, and basophil) function, production, kinetics, and response to various physiological and disease states. Using this information, veterinary practitioners should be able to interpret leukogram data from sick and healthy dogs and cats. Specifically, characteristic leukogram patterns such as physiological leukocytosis, corticosteroid-associated changes, and the presence of infection or severe inflammation should be recognized. In addition, interpretation of individual leukocyte responses should be possible. Several tables have been provided to assist in constructing a differential diagnosis to explain increases or decreases in absolute leukocyte numbers that lie outside of expected reference intervals.