Assessment of Y chromosome copy number alterations in non-neoplastic and neoplastic leukocytes of male dogs

The loss of the Y chromosome (ChrY), also known as LOY, is a common genetic alteration observed in men. It occurs in non-neoplastic cells as an age-related change as well as in neoplastic cells of various cancer types. While well-documented in humans, LOY has not been extensively studied in non-human mammals. In this study, we developed simple digital PCR-based assays to assess the copy number of ChrY relative to the X chromosome (ChrX) and chromosome 8 (Chr8) to evaluate ChrY numerical alterations in male canine DNA specimens. Using these assays, we analyzed non-neoplastic leukocytes from 162 male dogs without hematopoietic neoplasia to investigate the occurrence of age-related LOY in non-neoplastic leukocytes. Additionally, we examined 101 tumor DNA specimens obtained from male dogs diagnosed with various types of lymphoma and leukemia to determine whether copy number alterations of the ChrY occur in canine hematopoietic cancers. Analysis of the 162 non-neoplastic leukocyte DNA specimens from male dogs of varying ages revealed a consistent ∼1:1 ChrY:ChrX ratio. This suggests that age-related LOY in non-neoplastic leukocytes is rare or absent in dogs. Conversely, a decreased or increased ChrY:ChrX ratio was detected in canine neoplastic leukocytes at varying frequencies across different canine hematopoietic malignancies (P = 0.01, Fisher's exact test). Notably, a higher incidence of LOY was observed in more aggressive cancer types. To determine if this relative LOY to ChrX was caused by changes in ChrY or ChrX, we further analyzed their relative copy numbers using Chr8 as a reference. Loss of ChrX relative to Chr8 was found in 21% (9/41) of B-cell lymphomas and 6% (1/18) of non-T-zone/high-grade T-cell lymphomas. In contrast, a subset (29%, 4/14) of T-cell chronic lymphocytic leukemia showed gain of ChrX relative to Chr8. Notably, no relative LOY to Chr8 was detected indolent hematopoietic cancers such as T-zone lymphoma (0/9) and chronic lymphocytic leukemia of B-cell (0/11) and T-cell origins (0/14). However, relative LOY to Chr8 was present in more aggressive canine hematopoietic cancers, with incidences of 24% (10/41) in B-cell lymphoma, 44% (8/18) in non-T-zone/high-grade T-cell lymphoma, and 75% (6/8) in acute leukemia. This study highlights both similarities and differences in LOY between human and canine non-neoplastic and neoplastic leukocytes. It underscores the need for further research into the role of ChrY in canine health and disease, as well as the significance of LOY across various species.

B-cell leukemia in an adult sheep

B-cell leukemia is a rare form of hematologic neoplasia in sheep, especially in adult animals. We present a case report of a 5-year-old WhiteFace Sheep wether with suspected acute lymphoblastic leukemia. The patient, a second-generation relative of ewes experimentally inoculated with atypical scrapie, exhibited acute lethargy and loss of appetite. Laboratory investigation revealed marked leukocytosis, lymphocytosis, and abnormal serum chemistry panel results. Microscopic examination of blood and bone marrow smears exhibited a high percentage of large neoplastic cells with lymphoid characteristics. Histopathologic analysis of the spleen, liver, lungs, and other organs confirmed the presence of widespread tissue infiltration by neoplastic cells. Immunohistochemical labeling demonstrated strong intracytoplasmic labeling for CD20, consistent with B-cell neoplasia. Flow cytometric analysis confirmed the B-cell lineage of the neoplastic cells. Screening for bovine leukemia virus, which can experimentally cause leukemia in sheep, yielded a negative result. In this case, the diagnosis of B-cell leukemia was supported by a comprehensive panel of diagnostic evaluations, including cytology, histopathology, immunohistochemistry, and immunophenotyping. This case report highlights the significance of accurate diagnosis and classification of hematologic neoplasia in sheep, emphasizing the need for immunophenotyping to aid in the diagnosis of B-cell leukemia. It also emphasizes the importance of considering spontaneous leukemia as a differential diagnosis in sheep with lymphoid neoplasia, especially in the absence of circulating infectious diseases.

B-cell small lymphocytic lymphoma in a free-ranging South American fur seal (Arctocephalus australis)

Lymphomas are malignant neoplasms of the hematopoietic system arising from lymphocytes with highly variable biologic behavior. B-cell small lymphocytic lymphoma (B-SLL) is a non-Hodgkin lymphoma infrequently described in domestic and wild animals. The present study describes a case of B-SLL in a free-ranging adult male Arctocephalus australis in Brazil. The main necropsy findings included poor body condition, generalized lymphadenomegaly, severe and diffuse splenomegaly, and multiple, white to yellow nodules in the kidneys and small intestine. Histologically, these organs were partially or totally effaced by neoplastic small lymphocytes arranged in sheets, with moderate anisocytosis and anisokaryosis and a low mitotic count. These cells diffusely immunolabeled for CD79α and CD20, and were negative for CD3. A diagnosis of multicentric B-SLL was established and to the authors' knowledge, it has not been previously described in this genus.

Fecal acute phase proteins in cats with chronic enteropathies

BACKGROUND

Chronic enteropathies (CE) are common in cats and reliable biomarkers that can distinguish different causes and predict or monitor response to treatment are currently lacking.

HYPOTHESIS

To evaluate certain acute phase proteins in feces that could potentially be used as biomarkers in cats with CE.

ANIMALS

Twenty-eight cats with either inflammatory bowel disease (IBD; n = 13), food-responsive enteropathy (FRE; n = 3) or small cell gastrointestinal lymphoma (SCGL; n = 12) and 29 healthy control cats were prospectively enrolled.

METHODS

Fecal concentrations of haptoglobin, alpha-1-acid-glycoprotein (AGP), pancreatitis-associated protein-1 (PAP-1), ceruloplasmin, and C-reactive protein (CRP) were measured using Spatial Proximity Analyte Reagent Capture Luminescence (SPARCL) immunoassays before and after initiation of treatment. Cats were treated with diet and/or prednisolone (IBD cats), plus chlorambucil (SCGL cats).

RESULTS

Compared with controls, median fecal AGP concentrations were significantly lower (25.1 vs 1.8 μg/g; P = .003) and median fecal haptoglobin (0.17 vs 0.5 μg/g), PAP-1 (0.04 vs 0.4 μg/g) and ceruloplasmin (0.15 vs 4.2 μg/g) concentrations were significantly higher (P < .001) in cats with CE. Median fecal AGP concentrations were significantly lower (P = .01) in cats with IBD and FRE (0.6 μg/g) compared with cats with SCGL (10.75 μg/g). A significant reduction was found in CE cats after treatment for median fecal ceruloplasmin concentrations (6.36 vs 1.16 μg/g; P = .04).

CONCLUSIONS

Fecal AGP concentration shows promise to differentiate cats with SCGL from cats with IBD and FRE. Fecal ceruloplasmin concentrations may be useful to objectively monitor response to treatment in cats with CE.

Characterization of the intestinal mucosal proteome in cats with inflammatory bowel disease and alimentary small cell lymphoma

BACKGROUND

Current tests for diagnosis and differentiation of lymphoplasmacytic enteritis (LPE) and small cell lymphoma (SCL) in cats are expensive, invasive, and lack specificity. The identification of less invasive, more reliable biomarkers would facilitate diagnosis.

OBJECTIVES

To characterize the mucosal proteome in endoscopically obtained, small intestinal tissue biopsy specimens. We hypothesized that differentially expressed proteins could be identified and serve as biomarker candidates for the differentiation of LPE and SCL in cats.

ANIMALS

Six healthy control cats, 6 cats with LPE, and 8 cats with SCL.

METHODS

The mucosal proteome was analyzed using 2-dimensional fluorescence difference gel electrophoresis (2D DIGE) and nanoflow liquid chromatography tandem mass spectrometry. For 5 proteins, results were verified by Western blot analysis.

RESULTS

A total of 2349 spots were identified, of which 9 were differentially expressed with a ≥2-fold change between healthy cats and cats with LPE and SCL (.01 < P < .001). Eight of these 9 spots were also differentially expressed between cats with LPE and cats with SCL (P .001 < P < .04). However, Western blot analysis for malate dehydrogenase-1, malate dehydrogenase-2, apolipoprotein, annexin IV, and annexin V did not confirm significant differential protein expression for any of the 5 proteins assessed.

CONCLUSIONS AND CLINICAL IMPORTANCE

Two-D DIGE did not identify potential biomarker candidates in the intestinal mucosa of cats with LPE and SCL. Future studies should focus on different techniques to identify biomarker candidates for cats with chronic enteropathies (CE).

Rapid clinical progression of B-cell chronic lymphocytic leukemia in a horse

CASE DESCRIPTION

A 17-year-old Friesian gelding was examined at a referral hospital because of a 1-month history of mild exercise intolerance and marked lymphocytosis.

CLINICAL FINDINGS

Physical examination revealed no peripheral lymphadenopathy or other abnormalities. Results of an abdominal palpation examination per rectum and thoracic and abdominal ultrasonographic examinations were unremarkable. B-cell chronic lymphocytic leukemia (CLL) was diagnosed on the basis of severe lymphocytosis and positive expression of the B-cell marker CD20 by lymphocytes in the bone marrow and peripheral blood.

TREATMENT AND OUTCOME

Treatment with prednisolone (2 mg/kg [0.9 mg/lb], PO, every other day) and chlorambucil (20 mg/m², PO, every 3 weeks for 2 doses, then every 2 weeks) was initially associated with improvement in clinical signs and a decrease in the lymphocyte count. However, 3 weeks after administration of the first dose of chlorambucil, the lymphocyte count began to increase. One week later, the horse developed episodes of recurrent fever and the lymphocyte count continued to increase. Despite continued administration of the prednisolone-chlorambucil protocol, the horse's clinical condition deteriorated rapidly, and it was euthanized 6 weeks after initial examination at the referral hospital because of a poor prognosis. A necropsy was not performed.

CLINICAL RELEVANCE

B-cell CLL has been infrequently described in horses. This report was the first to describe the use of chemotherapy, albeit unsuccessful, for the treatment of B-cell CLL in a horse. This information should be useful for guiding expectations for prognosis and management of other horses affected with the disease.

Differentiation of lymphocytic-plasmacytic enteropathy and small cell lymphoma in cats using histology-guided mass spectrometry

BACKGROUND

Differentiation of lymphocytic-plasmacytic enteropathy (LPE) from small cell lymphoma (SCL) in cats can be challenging.

HYPOTHESIS/OBJECTIVE

Histology-guided mass spectrometry (HGMS) is a suitable method for the differentiation of LPE from SCL in cats.

ANIMALS

Forty-one cats with LPE and 52 cats with SCL.

METHODS

This is a retrospective clinicopathologic study. Duodenal tissue samples of 17 cats with LPE and 22 cats with SCL were subjected to HGMS, and the acquired data were used to develop a linear discriminate analysis (LDA) machine learning algorithm. The algorithm was subsequently validated using a separate set of 24 cats with LPE and 30 cats with SCL. Cases were classified as LPE or SCL based on a consensus by an expert panel consisting of 5-7 board-certified veterinary specialists. Histopathology, immunohistochemistry, and clonality testing were available for all cats. The panel consensus classification served as a reference for the calculation of test performance parameters.

RESULTS

Relative sensitivity, specificity, and accuracy of HGMS were 86.7% (95% confidence interval [CI]: 74.5%-98.8%), 91.7% (95% CI: 80.6%-100%), and 88.9% (95% CI: 80.5%-97.3%), respectively. Comparatively, the clonality testing had a sensitivity, specificity, and accuracy of 85.7% (95% CI: 72.8%-98.7%), 33.3% (95% CI: 14.5%-52.2%), and 61.5% (95% CI: 48.3%-74.8%) relative to the panel decision.

CONCLUSIONS AND CLINICAL IMPORTANCE

Histology-guided mass spectrometry was a reliable technique for the differentiation of LPE from SCL in duodenal formalin-fixed paraffin-embedded samples of cats and might have advantages over tests currently considered state of the art.

B-cell chronic lymphocytic leukemia in a miniature American Eskimo dog

An 11-year-old neutered male miniature American Eskimo dog was presented for routine dental cleaning with moderately enlarged submandibular, prescapular, and popliteal lymph nodes. On pre-anesthetic blood analysis a moderate, poorly regenerative anemia and marked lymphocytosis were observed. Although cytologic evaluation of a lymph node aspirate was interpreted as lymphoma, a complete blood cell count, flow cytometric immunotyping of blood leukocytes, and serum electrophoresis identified B-cell chronic lymphocytic leukemia. Chemotherapy with chlorambucil was recommended.

Preferential use of unmutated immunoglobulin heavy variable region genes in Boxer dogs with chronic lymphocytic leukemia

Human chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease, and immunoglobulin heavy variable region (IGHV) gene mutational status is an important prognostic marker. IGHV mutational status has not been previously examined in canine CLL. We sequenced the IGHV-D-J rearrangements from 55 canine patients with CLL, including 36 non-Boxer and 19 Boxer dogs. The majority of non-Boxers (75%) had mutated IGHV genes, whereas the majority of Boxers (79%) had unmutated IGHV genes. IGHV3-41 and IGHV3-67 gene usage was significantly higher in Boxers with CLL compared to non-Boxers. Additionally, 11 Boxers with large B-cell lymphoma and the normal IGHV repertoire of six control dogs (three Boxers and three non-Boxers) were sequenced. IGHV3-41 was preferentially used in Boxers with other forms of lymphoma and without lymphoproliferative disease. However, preferential use of unmutated IGHV genes was unique to Boxers with CLL, suggesting Boxers may be a valuable model to investigate unmutated CLL.

Changes in C-reactive protein and haptoglobin in dogs with lymphatic neoplasia

Acute phase proteins (APP) are regarded as a useful diagnostic tool in humans with lymphomas, leukaemias and multiple myeloma. C-reactive protein (CRP) and haptoglobin concentrations were measured in dogs with malignant multicentric (high grade) lymphoma (n=16), acute lymphoblastic leukaemia (ALL) (n=11), chronic lymphocytic leukaemia (CLL) (n=7) and multiple myeloma (n=8). Twenty-five healthy dogs served as controls. Measurements of the CRP plasma concentration were performed using a commercial ELISA and haptoglobin was measured with an assay based on its haemoglobin binding capacity. Global group comparisons using Kruskal-Wallis-test revealed significant group differences for both APPs (P<0.0001). Median CRP concentrations were increased in all groups with neoplastic lymphatic disorders (lymphoma: 37.2mg/L, ALL: 47.8mg/L, CLL: 35.5mg/L, myeloma: 17.6mg/L) compared to controls (1.67mg/L; P<0.001). Compared to the healthy controls (median=0.59g/L), haptoglobin was especially increased in dogs with ALL (6.8g/L, P<0.0001) followed by dogs with malignant lymphoma (3.8g/L, P<0.0001), CLL (3.2g/L, P=0.0008), and multiple myeloma (3.0g/L, P=0.0163). For both APPs, a wide range of values was found in all patient groups. The results indicate that particularly severe and acute lymphatic neoplasia, such as high grade lymphoma and ALL, cause significant acute phase reactions in dogs and must be included in the differential diagnoses of increased blood levels of these APPs.

Flow cytometric expression of common antigens CD18/CD45 in blood from dogs with lymphoid malignancies: A semi-quantitative study

Flow cytometry is useful to study lymphoid malignancies since it allows both immunophenotyping of neoplastic cells and quantification of antigen expression. CD18 and CD45 are commonly exposed membrane antigens with different levels of expression on blood leukocyte and neoplastic cells. The aim of this retrospective study was to semi-quantitatively evaluate the expression of CD18 and CD45 in dogs with different lymphoid malignancies with blood involvement and to compare results with those from healthy dogs and dogs with reactive diseases. Blood samples from 13 dogs with precursor lymphoid malignancies, 20 with mature neoplasms (either chronic lymphocytic leukaemia or lymphoma), of different immunophenotypes, were compared with 24 healthy dogs and 12 dogs with different reactive diseases. The median fluorescence intensity (MFI) for CD18 and CD45 was recorded on lymphoid and granulocytic populations using dual colour flow cytometry, and the ratio between MFI for lymphoid and granulocytic populations (L/N ratio) was calculated to compare the results obtained in different sessions using an internal control (granulocyte fluorescence intensity). Significant decreases in the L/N ratio were detected in neoplastic samples for both CD18 (either precursors or mature versus controls) and CD45 (either precursors or mature versus control), while using MFI only slight differences were detectable in CD45 between precursors and controls. Neoplastic cells often exhibited lower expression of the L/N ratio for CD18, and mainly for CD45, most likely due to a less mature pattern than normal cells and/or to an aberrant quantitative expression of surface antigen. Moreover, more than 50% of neoplastic lymphoid cells exhibited L/N ratios that were not within the values observed in controls for at least one antigen. Altered L/N ratios, in particular decreases of CD45, were mainly observed in precursor neoplasms and in T-cell neoplasms. Detection of altered expression of common antigens, and in particular a L/N ratio for CD45 lower than a value of 103% may be useful as a confirmation of pseudo-clonality thus helping in differentiating reactive and neoplastic lymphocyte expansions.

Differentiating benign and malignant causes of lymphocytosis in feline bone marrow

Differentiation of benign and malignant causes of lymphocytosis in blood or bone marrow can be problematic. In the present study, reports of examinations of bone marrow from cats, submitted over an 8-year period, were reviewed to identify cats with increased numbers of small lymphocytes. Of 203 reports reviewed, 12 (5.9%) indicated increased numbers of small lymphocytes. Diagnoses for these cats included chronic lymphocytic leukemia (CLL; n = 2), pure red cell aplasia (PRCA; n = 4), immune-mediated hemolytic anemia (IMHA; n = 3), thymoma (n = 1), cholangiohepatitis (n = 1), and fever of unknown origin (n = 1). Several factors were identified that could be used to differentiate reactive lymphocytosis from CLL. Cats with CLL tended to be older, and lymphocytes were slightly larger and had cleaved or lobulated nuclei. Reactive lymphocytosis was associated with immune-mediated anemias and inflammatory diseases. In reactive lymphocytosis, the proliferating lymphocytes were organized into lymphoid aggregates in bone marrow and were predominately B cells. Alternatively, in CLL and thymoma, the proliferating lymphocytes were diffusely distributed and were predominately T cells. Therefore, differentiation of the causes of lymphocytosis should include evaluation of signalment, concurrent disease conditions, lymphocyte morphology, lymphocyte distribution in bone marrow, and immunophenotype. Cat age, presence of severe anemia, and evidence of inflammatory disease also should be considered.

Treatment of chronic lymphocytic leukaemia in three dogs with melphalan and prednisolone

Three adult dogs with chronic lymphocytic leukaemia (CLL) were successfully treated with melphalan and prednisolone. Based on the immunophenotypic analysis of leukaemic cells, two dogs were diagnosed with B cell CLL and one dog was tentatively diagnosed as having T cell CLL. One dog with B cell CLL had IgM monoclonal gammopathy. The clinical signs and haematological abnormalities associated with CLL in the three dogs improved with the administration of cytoreductive melphalan (3 to 5 mg/m2/day) and prednisolone (4.3 to 30 mg/m2/day) for eight to 210 days. There were no severe adverse effects except a mild increase in plasma alkaline phosphatase activity. Melphalan and prednisolone therapy may achieve remission with few side effects in dogs with CLL.

Diagnosis and management of B cell chronic lymphocytic leukaemia in a cat

A four-year-old, female neutered domestic shorthair cat had a history of chronic intermittent vomiting and lymphocytosis. B cell chronic lymphocytic leukaemia was diagnosed by flow cytometry, which revealed abnormally large numbers of mature B lymphocytes in the peripheral blood. The cat was treated conservatively with antiemetic drugs and remained stable without chemotherapy for over a year.

Chronic lymphocytic leukemia in dogs and cats: the veterinary perspective

Chronic lymphocytic leukemia (CLL) in dogs and cats shares many similarities with its human counterpart but also has significant differences. In marked contrast to people, CLL in dogs and cats is primarily a T-lymphocyte proliferation. Cytotoxic T-cell proliferations with granular lymphocyte morphology predominate in dogs, and T helper cell proliferations seem to be most common in cats with CLL. Immunophenotyping and assessment of clonality by molecular genetic analysis are newer adjunctive tools in veterinary medicine that are useful in the characterization and diagnosis of CLL in dogs and cats. The clinical presentation, typical hematologic findings, diagnosis, course of disease, prognosis, and therapy of CLL in dogs and cats are discussed.

Hypercalcaemia associated with chronic lymphocytic leukaemia in a Giant Schnauzer

A 7-year-old male Giant Schnauzer was referred with a history of severe vomiting, lethargy, weight loss, polydipsia and polyuria. Detailed investigations revealed leucocytosis with a marked lymphocytosis, mild non-regenerative anaemia, thrombocytopenia, hypercalcaemia and azotaemia. Circulating lymphocytes were small and well-differentiated, and the same lymphoid population was present in bone marrow. Chronic lymphocyctic leukaemia with associated paraneoplastic hypercalcaemia was diagnosed. Immunohistochemical staining of a bone marrow biopsy revealed a neoplastic B-cell line expressing CD79. The dog responded to therapy with prednisolone and chlorambucil for a period of 8 months.

An immunophenotypic study of canine leukemias and preliminary assessment of clonality by polymerase chain reaction

There is a relative lack of information in the veterinary literature regarding the immunophenotypes present in canine leukemias. Utilizing a panel of thirty monoclonal antibodies, canine leukemias were assessed by flow cytometry alone or by flow cytometry in combination with immunocytochemical staining of smears. Canine chronic lymphocytic leukemia (CLL) occurred in older dogs (mean age 9.75 years; range 1.5-15 years; n = 73 cases). Blood lymphocyte counts ranged from 15,000 to 1,600,000/microl. Surprisingly, 73% of CLL cases involved proliferation of T lymphocytes (CD3+), and 54% of CLL cases had large granular lymphocyte (LGL) morphology. LGL CLL's were almost exclusively proliferation's of T cells that expressed CD8 and the leukointegrin alphaDbeta2 and more frequently expressed T cell receptor (TCR) alphabeta (69%) than TCRgammadelta (31%). The non-LGL T cell CLL cases (19% of CLL) involved proliferation of TCRalphabeta T cells in which no consistent pattern of CD4 or CD8 expression was found. B cell CLL, based on expression of CD2 or CD79a, comprised 26% of canine CLL cases. These results are in marked contrast to people where greater than 95% of CLL cases involve proliferation of B lymphocytes. Thirty eight (38) acute leukemias were also immunophenotyped. The majority (55%) of these leukemias had a phenotype most consistent with a myeloid origin. Acute LGL leukemias were also observed (7/38), although less commonly than the CLL counterpart. CD34 expression was common in acute, non-LGL leukemias of dogs, both myeloid and lymphoid. In some circumstances, it can be difficult to differentiate a reactive (polyclonal) lymphoid proliferation from a neoplastic (monoclonal) one. Therefore, as an adjunct to phenotypic studies, we have developed a polymerase chain reaction (PCR) based test for assessment of clonality in T cell proliferations. The test amplifies the junction of the variable gamma (Vgamma) and joining gamma (Jgamma) gene segments region of the TCR gamma genes. Preliminary data indicates that our test is effective and is capable of differentiating a neoplastic from a reactive lymphoproliferative process.

Vaccine-induced cytotoxic T lymphocytes protect against retroviral challenge

The development of prophylactic vaccines against retroviral diseases has been impeded by the lack of obvious immune correlates for protection. Cytotoxic T-lymphocyte (CTL), CD4-lymphocyteS, chemokine and/or antibody responses have all been associated with protection against HIV and AIDS; however, effective and safe vaccination strategies remain elusive. Here we show that vaccination with a minimal ovine CTL peptide epitope identified within gp51 of the retrovirus bovine leukemia virus (BLV), consistently induced peptide-specific CTLs. Only sheep whose CTLs were also capable of recognizing retrovirus-infected cells were fully protected when challenged with BLV. This retrovirus displays limited sequence variation; thus, in the relative absence of confounding CTL escape variants, virus-specific CTLs targeting a single epitope were able to prevent the establishment of a latent retroviral infection.

[Determination of kinetic parameters lymphocyte populations in cows with chronic lymphocytic leukemia]

We analyzed changes in the number of lymphocytes in the blood of cows with chronic lymphoid leukemia using the Gomperts equation of population dynamics. The parameters of this equation were determined. Coefficients beta and gamma proved to be the most variable. The former reflects the delay and the latter characterizes the maximum rate of growth of the lymphocyte population. According to these parameters, three groups of animals were distinguished with different kinetics of leucosis and different correlations between immuno-hematological indices.

Lentivirus infection in an African lion: a clinical, pathologic and virologic study

In May 1991, clinical, pathologic, and virologic investigations were carried out on an 8-yr-old male lion (Panthera leo), with recurrent infections, in captivity with two lionesses in the Zoological Garden of Pistoia, Tuscany, Italy. The lion had severe pneumonia, neutropenia, thrombocytopenia, and an increase in blood urea nitrogen and creatininemia; in spite of therapy, it died within 3 months. At necropsy, the animal had a lymphoma and other lesions similar to those described in feline immunodeficiency virus-infected cats. We identified FIV gag-sequence using PCR amplification of lymph node tissues.

Immunoglobulin-producing tumours in dogs and cats

Tumours with a plasmacytoid pattern taken from 32 dogs and four cats were examined for the presence of immunoglobulins, which would allow them to be designated as B-cell lymphomas. Within a total of 19 immunoglobulin-positive tumours, three types could be distinguished: extramedullary plasmacytoma (15), multiple myeloma (two) and immunocytoma (two). These tumours occurred in 18 of the dogs, and in one cat (extramedullary plasmacytoma). The characteristics of the immunoglobulin-producing tumours were investigated by light and electron-microscopy as well as by immunohistochemical methods. Seventeen of the 19 tumours expressed lambda-type light chains and one tumour kappa-type light chains. Heavy chains were also synthesized by five tumours.

Lymphoplasmacytic lymphoma in a stallion

Lymphoplasmacytic lymphoma found in a 6-year-old Anglo-Arabian stallion was investigated histologically, immunohistochemically and ultrastructurally. The animal showed a large mediastinal mass and generalized lymph node involvement. The neoplastic cells were in various differentiation stages of small lymphocyte, centrocyte, centroblast, immunoblast and plasma cell. Some neoplastic cells showed positive cytoplasmic reactivity for mu and lambda chains. There were well developed rough endoplasmic reticulum (RER) and Golgi complexes in plasmacytoid cells, and slightly developed RER or a few long strands of RER in medium-sized to large lymphoid cells. These findings suggest that this neoplasm is of B-cell origin.

Differentiation of chronic lymphocytic leukemia in the horse. A report of two cases

Chronic lymphocytic leukemia (CLL) was diagnosed in two horses: an 18-year-old Quarter Horse gelding that was examined because of edema of the prepuce and ventral abdomen; and a 20-year-old mixed breed gelding that was referred because of lymphocytosis, ventral edema, and weight loss. The first horse had enlarged peripheral lymph nodes and cool nonpainful pitting edema of the ventral abdomen and prepuce. The second horse had enlarged peripheral lymph nodes, cool nonpainful pitting edema of the ventral thorax and cranial ventral abdomen, and a 3/5 holosystolic heart murmur. The diagnosis of CLL was based on increased blood lymphocyte counts and infiltration of marrow and other tissues by lymphocytes. In horse 1, the lymphocytosis persisted for 2 months between initial examination and death. The results of flow cytometric analysis on blood lymphocytes using anti-lymphocyte antibodies suggested that horse 1 had T-cell CLL, and horse 2 had B-cell CLL. In addition, the second horse had a monoclonal gammopathy (IgG), with light-chain proteinuria.

Classification of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphomas

A retrospective histologic study was made of 1,198 cases of bovine lymphoma using the National Cancer Institute Working Formulation for human non-Hodgkin's lymphoma. This classification scheme was found to be readily applicable to bovine lymphoma. Most of the cell types described in the National Cancer Institute Working Formulation occurred in this series of bovine lymphomas, but the distribution of cell types varied markedly compared to that of human beings. Eighty-nine percent (1,067/1,198) of bovine lymphomas were high-grade tumors. The diffuse large cell type and its cleaved variant comprised 65.9% of all bovine lymphomas. Similar to the dog, but in marked contrast to human beings where at least 34% of non-Hodgkin's lymphomas were follicular, follicular tumors were found to be extremely rare in cattle (0.3% or 4/1,198). The prevalence of cell types varied significantly between the enzootic and sporadic lymphomas. The cleaved variant of the diffuse large cell type constituted 38% (406/1,072) of enzootic lymphomas versus 14% (18/126) of sporadic lymphomas. The mitotic index (100 x oil immersion field, 175 microns in diameter) of enzootic lymphomas (3.72 +/- 0.06, mean +/- standard error) was significantly greater than the mitotic index of sporadic lymphomas (2.82 +/- 0.17). We concluded that the cleaved variant of the diffuse large cell type with high mitotic index is characteristic of enzootic lymphoma. This characteristic high-grade cell type may be a consequence of the viral etiology of the enzootic form of bovine lymphoma.

Malignant lymphoma in ferrets: clinical and pathological findings in 19 cases

The clinical and pathological findings in 19 ferrets (Mustela putorius furo) with malignant lymphoma are reviewed. Peripubescent ferrets had rapidly progressive stage IV high grade immunoblastic or small non-cleaved cell lymphoma. Adult ferrets had stage II or IV low grade diffuse small lymphocytic (DSL) lymphoma, stage IV high grade small non-cleaved cell lymphoma, or stage IV high grade immunoblastic polymorphous (IBP) lymphoma. Three ferrets had concurrent IBP and DSL lymphoma involving different organs. The IBP admixture of immunoblasts, large atypical lymphocytes, Reed-Sternberg-like cells, lymphoblasts and small lymphocytes has been associated with certain retrovirally associated lymphomas and nodal hyperplasias in man, non-human primates and cats. Aleutian disease, a parvovirus-induced lymphoproliferative disease, also involves clinical and histological features similar to certain lymphomas in ferrets. Seven ferrets tested were seronegative for feline leukaemia virus antigen. Only one of eight ferrets was positive for Aleutian parvovirus antibody. The clinical and pathological findings are suggestive of a viral aetiology for certain lymphomas in ferrets.

Pigmented villonodular synovitis and plasmacytoid lymphoma in a dog

A 4-year-old Labrador Retriever was examined because of progressive left hind limb lameness involving the stifle. A villous synovial mass was evacuated by synovectomy. Initially, the macroscopic and histopathologic features suggested a malignant fibrosarcomatous process; however, further histologic studies revealed lesions consistent with pigmented villonodular synovitis. Nine months later, the dog developed a large retroperitoneal tumor, with metastasis to the lungs and liver. The dog was then euthanatized. By histologic and electron microscopic examinations, the tumor was found to be a primitive plasmacytoid lymphoma.

[The absence of DNA methylase activity in Drosophila cells]

DNA methylase activity has been studied in partially purified extracts from cultured cells, embryos, and adult Drosophila flies. No significant level of transfer of methyl groups from S-adenosylmethionine with formation of 5-methylcytosine and 6-methyladenine was observed. Methylase activity in Drosophila cells as compared to bovine lymphocytes and rat liver is either absent or at least 5000-15,000 times lower and hence cannot be detected using the present method.

Spontaneous nonthymic T cell lymphomas in young Wistar rats

Spontaneous acute lymphomas and related leukemias, occurring in three of 2,974 male Wistar rats used as controls in toxicity studies during the last 14 years (1974-1987), were examined by light and electron microscopy and by using immunohistochemistry. At autopsy, conspicuous hepatosplenomegaly was noted. Morphologically, tumor cells of all three rats were medium-sized lymphocytes with many mitotic figures proliferating mainly in the spleen, liver, and bone marrow. Virus-like particles were not detected. Immunohistochemically, almost all tumor cells were positive for thy-1 antigen but negative for hematopoietic and differentiation markers such as W3/13, W3/25, OX4, OX8, and OX12. The results suggest that the lymphomas in these three rats were derived from T cells.

Quantitative binding of Fc-receptors, and antibody-dependent cell-mediated cytotoxicity of blood lymphocytes in healthy and chronic lymphocytic leukemic cattle

The binding capacity of Fc-receptors for IgG of blood lymphocytes was studied in healthy cattle and cattle with chronic lymphocytic leukemia before and after incubation at 37 degrees C in basal Eagle's medium without serum. It was found that lymphocytes of leukemic cattle possess twice the amount of Fc-receptors found in normal lymphocytes. The changes in the binding capacity of Fc-receptors for IgG of normal and leukemic lymphocytes correlated with those of antibody-dependent cell-mediated cytotoxicity (ADCC) of the corresponding lymphocytes. The lower ADCC of leukemic lymphocytes in comparison with normal ones was accompanied by a lower association constant of the leukemic lymphocyte Fc-receptors towards IgG.

RAV-1 insertional mutagenesis: disruption of the c-myb locus and development of avian B-cell lymphomas

Infection of young chickens with RAV-1, a subgroup A isolate of avian leukosis virus, results in the development of lymphoid leukosis, a B-cell lymphoma characterized by provirus insertion into the c-myc locus. We report here that when 12- to 13-day-old embryos rather than 1-day-old chickens were infected with RAV-1, a novel B-cell lymphoma developed in which proviral insertions had activated expression of the c-myb gene. These tumors expressed elevated levels of a 4.5-kilobase myb-containing mRNA transcript that contained c-myb sequences not found in v-myb. The c-myc locus in these tumors appeared normal. The biological properties of the activated myb lymphoma were distinct from those of lymphoid leukosis. Metastatic disease developed within 7 weeks of infection. Distinct intermediate pathogenic stages with preneoplastic and primary neoplastic lesions were not detected. Although bursal tissues appeared to be nonmalignant on gross examination, Southern analyses of bursal DNA revealed the presence of tumor with the same clonal origin as abdominal lymphoma masses. The dependence on embryonic infection for development of activated myb lymphoma suggests that the target cells in which c-myb is activated are found only in embryos and are distinct from those cells that give rise to lymphoid leukosis.

Lymphoid leucaemia in a dog after chemotherapy for mast cell sarcomas

A 10-year-old Golden Labrador developed a well-differentiated lymphoid cell leucaemia during chemotherapy for a malignant mast cell tumour. Similar treatment had been carried out 2 years previously for another mast cell tumour. The possibility of an association between the anti-neoplastic chemotherapy and the lymphatic leucaemia is discussed.

Observations on the pathology of non-alimentary lymphomas in the horse

A retrospective study was carried out on post-mortem and biopsy tissue samples from 26 horses with non-alimentary lymphoma. On the basis of their histopathology and cytology, the cases were grouped into several categories: (1) Lymphoblastic lymphomas (6 cases) and primary lymphoblastic leukaemia (2 cases). (2) Histiolymphocytic lymphomas involving the skin (6 cases) or lymph nodes (3 cases). (3) Lymphomas showing follicular development (4 cases). (4) Plasmacytic lymphomas (4 cases). (5) Lymphocytic lymphoma (1 case). Most affected horses were middle-aged or old but lymphoblastic neoplasms tended to affect younger horses than other forms. The course of the disease was highly variable. The most rapidly progressive forms were of lymphoblastic cytology, whereas some cases with histiolymphocytic skin nodules appeared to be only slowly progressive. Further information is needed on the pathology and clinical behaviour of some types of lymphoma, particularly those manifesting in the skin. Elucidation of the histogenetic relationships of the different cytological types of lymphoma will involve the development of immunohistochemical and other techniques which are specifically applicable to the horse.