Validation of an eight parameter immunophenotyping panel in adult canines for assessment of immunotoxicity

Cross-reactivity of human monoclonal antibodies with canine peripheral blood mononuclear cells

In drug development, the dog is often used as a model for non-rodent preclinical safety studies. In particular, immunophenotyping in dogs can be important to characterize the toxicological profile of a test item. A wide range of antibodies specific to surface antigens is needed, however, commercially available antibodies to dog are scarce. To date, numerous studies have reported the cross-reactivity of human monoclonal antibodies with canine peripheral blood mononuclear cells (PBMC). In this study, we aimed to increase the number of canine-specific antibodies and took a rather novel approach to further determine cross-reactivity of 378 human recombinant antibodies lacking Fc regions to surface antigens on canine PBMC. The screening resulted in 30 human monoclonal antibodies well reactive to canine PBMC. Sequence homology of the targeted human and canine antigens was analyzed with Basic Local Alignment Search Tool. Thirteen human cross-reactive antibodies of interest were analyzed with cells from canine whole blood in combination with lineage markers. Finally, ten antibodies were identified as useful markers for the application in dog. Except for CD27, the remaining nine antibodies are already commercially available human cross-reactive antibodies. This study provides a new source for all ten antibodies described here.

Immunotoxicity, genotoxicity and epigenetic toxicity of nanomaterials: New strategies for toxicity testing?

The unique properties of nanomaterials (NMs) are beneficial in numerous industrial and medical applications. However, they could also induce unintended effects. Thus, a proper strategy for toxicity testing is essential in human hazard and risk assessment. Toxicity can be tested in vivo and in vitro; in compliance with the 3Rs, alternative strategies for in vitro testing should be further developed for NMs. Robust, standardized methods are of great importance in nanotoxicology, with comprehensive material characterization and uptake as an integral part of the testing strategy. Oxidative stress has been shown to be an underlying mechanism of possible toxicity of NMs, causing both immunotoxicity and genotoxicity. For testing NMs in vitro, a battery of tests should be performed on cells of human origin, either cell lines or primary cells, in conditions as close as possible to an in vivo situation. Novel toxicity pathways, particularly epigenetic modification, should be assessed along with conventional toxicity testing methods. However, to initiate epigenetic toxicity screens for NM exposure, there is a need to better understand their adverse effects on the epigenome, to identify robust and reproducible causal links between exposure, epigenetic changes and adverse phenotypic endpoints, and to develop improved assays to monitor epigenetic toxicity.

Immunophenotyping pattern characterization in canine blood: towards a clinical application

Immunophenotyping is a widely used method for a precise diagnosis and classification of haematopoietic neoplasia in human beings and also in dogs. The gold standard for cell preparation is density gradient centrifugation of mononuclear cells. Alternatively, another way to separate human leukocytes is carrying out whole blood lysis. The aim of this study was to validate whole blood lysis as an alternative method in clinical veterinary procedures using an immunophenotype panel of leukocytes designed by our group. Flow cytometry study of adult canine leukocytes subset groups, using whole blood lysis or mononuclear cells tested against an array of canine leukocyte antibodies were done. Besides differential white blood cell counts were done. Also immunophenotyping studies in whole blood samples stored at 4 °C for 48 h were performed. The Coefficient Variation values were less than 20%, for most of the comparison. Consistent results were observed in phenotyping canine peripheral blood leukocytes. Stability results indicated that whole blood samples might be stored for 48 h without a significant difference in the data compared to samples processed immediately after blood collection. This study shows that whole blood lysis represents an efficient and quick alternative for canine leukocyte preparation. In addition, samples can be analysed immediately or stored for 48 h without a significant difference between them. This is relevant for veterinary medicine considering the lack of facilities in many laboratories to process samples.