Expression of CD61 (beta3 integrin subunit) on canine cells

Canine Mammary Neoplasia Induces Variations in the Peripheral Blood Levels of CD20, CD45RA, and CD99

The idea of using tumour biomarkers as diagnostic tools is progressively increasing. Of these, serum biomarkers are of particular interest, as they can provide rapid results. In the present study, serum samples from 26 bitches diagnosed with mammary tumours, plus 4 healthy bitches, were obtained. The samples were analysed using CD antibody microarrays targeting 90 CD surface markers and 56 cytokines/chemokines. A total of five CD proteins, namely CD20, CD45RA, CD53, CD59, and CD99, were selected and further analysed, utilizing immunoblotting techniques to validate the microarray results. CD45RA showed a significantly lower abundance in the serum samples from the bitches carrying mammary neoplasia in comparison to the healthy animals. Regarding CD99, the serum samples from the neoplastic bitches showed it in a significantly higher abundance than those from the healthy patients. Finally, CD20 showed a significantly higher abundance in bitches carrying a malignant mammary tumour in comparison to healthy patients, but no differential expression between malignant and benign tumours was observed. According to these results, both CD99 and CD45RA are indicators of mammary tumour presence, but without distinguishing between malignant and benign.

Prospective diagnostic accuracy evaluation and clinical utilization of a modified assay for platelet-associated immunoglobulin in thrombocytopenic and nonthrombocytopenic dogs

BACKGROUND

No diagnostic tests reliably distinguish primary immune-mediated thrombocytopenia (pIMT) from other causes of thrombocytopenia.

OBJECTIVES

The purpose of the study was to evaluate diagnostic sensitivity and specificity using modified direct and indirect platelet-associated immunoglobulin (PAIg) assays and reticulated platelets (RP) by flow cytometry for the classification of thrombocytopenic dogs and differentiating pIMT.

METHODS

Platelets were isolated from plasma samples of thrombocytopenic dogs and nonthrombocytopenic healthy and ill dogs. For direct PAIg, they were analyzed by flow cytometry after incubation with anti-human amylase fluorescein isothiocyanate (FITC, negative control), anti-canine IgG-FITC, anti-canine IgM-FITC, and anti-human CD61-conjugated fluorochrome (AF647). For indirect PAIg, platelets from normothrombocytic dogs were incubated with thrombocytopenic dog plasma and analyzed similar to direct PAIg. RP percentages were determined based on forward light scatter vs thiazole orange fluorescence.

RESULTS

Seventy-five thrombocytopenic dogs, 16 nonthrombocytopenic ill dogs, and 24 healthy dogs were evaluated. Diagnostic sensitivity and specificity utilizing direct IgG was 29.4% and 75.9%, respectively; when combining direct/indirect assays (IgG/IgM), it was 76.5% and 65.5%, respectively, for distinguishing pIMT. For RP, no significant difference between pIMT and sIMT was noted. RP > 8% with positive PAIg had a sensitivity of 94% and specificity of 27.6% for distinguishing pIMT. There was a significant difference in platelet concentration and CD61% staining between control and pIMT.

CONCLUSIONS

The combined modified assays resulted in fair diagnostic sensitivity and specificity for the diagnosis of pIMT. The modification of the immunoglobulin assays improved diagnostic accuracy; however, a single panel to accurately classify thrombocytopenia remains elusive.

Launching a novel preclinical infrastructure: comparative oncology trials consortium directed therapeutic targeting of TNFalpha to cancer vasculature

Background

Under the direction and sponsorship of the National Cancer Institute, we report on the first pre-clinical trial of the Comparative Oncology Trials Consortium (COTC). The COTC is a novel infrastructure to integrate cancers that naturally develop in pet dogs into the development path of new human drugs. Trials are designed to address questions challenging in conventional preclinical models and early phase human trials. Large animal spontaneous cancer models can be a valuable addition to successful studies of cancer biology and novel therapeutic drug, imaging and device development.

Methodology/Principal Findings

Through this established infrastructure, the first trial of the COTC (COTC001) evaluated a targeted AAV-phage vector delivering tumor necrosis factor (RGD-A-TNF) to αV integrins on tumor endothelium. Trial progress and data was reviewed contemporaneously using a web-enabled electronic reporting system developed for the consortium. Dose-escalation in cohorts of 3 dogs (n = 24) determined an optimal safe dose (5×10¹² transducing units intravenous) of RGD-A-TNF. This demonstrated selective targeting of tumor-associated vasculature and sparing of normal tissues assessed via serial biopsy of both tumor and normal tissue. Repetitive dosing in a cohort of 14 dogs, at the defined optimal dose, was well tolerated and led to objective tumor regression in two dogs (14%), stable disease in six (43%), and disease progression in six (43%) via Response Evaluation Criteria in Solid Tumors (RECIST).

Conclusions/Significance

The first study of the COTC has demonstrated the utility and efficiency of the established infrastructure to inform the development of new cancer drugs within large animal naturally occurring cancer models. The preclinical evaluation of RGD-A-TNF within this network provided valuable and necessary data to complete the design of first-in-man studies.

Reactivity of cross-reacting monoclonal antibodies with canine leukocytes, platelets and erythrocytes

A panel of 380 commercially available monoclonal antibodies (mAbs) against human CD molecules from various sources was tested during the 8th Human Leukocyte Differentiation Antigen Workshop (HLDA8) for cross-reactivity on canine peripheral blood leukocytes by flow cytometry. In addition, all mAbs were used to label a 50:50 mixture of platelets and erythrocytes of the same dogs. This testing resulted in 51 cross-reacting mAbs. mAbs with specificity for CD9, CD29, CD42a, CD61, and CD41/CD61 showed cross-reactivity with canine platelets in a non-polymorphic and one mAb with the erythrocyte antigen CD235a in a polymorphic reaction pattern. Canine leukocyte-reactive mAbs included those with specificity for CD11a, CD11b, CD14, CD18, CD21, CD22, CD47, CD49d, CD49e, CD56, CD62L, CD91, CD94, and CD172a. In addition, several mAbs resulted in a staining pattern of canine cells which suggest that the canine epitope equivalents have an alternate expression pattern from that expected for humans (CD1a, CD35, CD44, CD45, CD75s, CD81). In summary, this study confirmed the reactivity of previously described cross-reactive mAbs with canine cells and resulted in the characterization of mAbs recognizing so far undetectable canine CD molecules.

Quantitation of reticulated platelets in healthy dogs and in nonthrombocytopenic dogs with clinical disease

BACKGROUND

Thrombocytopenia is a common disorder in dogs and development of an objective diagnostic assay to measure platelets newly released from bone marrow into the blood would provide a noninvasive way to predict megakaryocytopoiesis. Reticulated platelets are newly released platelets with increased concentrations of RNA that can be detected by flow cytometric analysis of blood stained with thiazole orange (TO).

OBJECTIVE

The goals of this study were to establish a reproducible method to quantitate reticulated platelets in dogs, to establish a reference interval for reticulated platelet percentages in healthy dogs, and to determine whether the percentage of reticulated platelets was nonspecifically increased in nonthrombocytopenic dogs with clinical disease.

METHODS

Blood samples were obtained from healthy dogs and from nonthrombocytopenic dogs presented for a variety of disorders. An aliquot of whole blood was stained with TO and a phycoerythrin-labeled monoclonal antibody to platelet CD61, then analyzed by flow cytometry.

RESULTS

The coefficients of variation were 7.8% to 15.6% (intra-assay precision) and 6.1% to 19.5% (interassay precision). Overnight storage for 18 to 26 hours, under variable conditions, resulted in an increase in the percentage of platelets staining with TO. The reference interval for reticulated platelets in the healthy control group was 0-4.3% (0-12,095/microL). No significant differences were found in the mean percentage of reticulated platelets or absolute concentration of reticulated platelets between control and affected dogs.

CONCLUSIONS

These studies demonstrate a reliable, noninvasive diagnostic assay for measurement of reticulated platelets in whole blood and provide a baseline for assessment of the clinical utility of the assay.