A monoclonal antibody selection for immunohistochemical examination of lymphoid tissues from non-human primates

Identifying major histocompatibility complex class II-DR molecules in bovine and swine peripheral blood monocyte-derived macrophages using mAb-L243

Major histocompatibility complex class II (MHC-II) molecules are involved in immune responses against pathogens and vaccine candidates' immunogenicity. Immunopeptidomics for identifying cancer and infection-related antigens and epitopes have benefited from advances in immunopurification methods and mass spectrometry analysis. The mouse anti-MHC-II-DR monoclonal antibody L243 (mAb-L243) has been effective in recognising MHC-II-DR in both human and non-human primates. It has also been shown to cross-react with other animal species, although it has not been tested in livestock. This study used mAb-L243 to identify Staphylococcus aureus and Salmonella enterica serovar Typhimurium peptides binding to cattle and swine macrophage MHC-II-DR molecules using flow cytometry, mass spectrometry and two immunopurification techniques. Antibody cross-reactivity led to identifying expressed MHC-II-DR molecules, together with 10 Staphylococcus aureus peptides in cattle and 13 S. enterica serovar Typhimurium peptides in swine. Such data demonstrates that MHC-II-DR expression and immunocapture approaches using L243 mAb represents a viable strategy for flow cytometry and immunopeptidomics analysis of bovine and swine antigen-presenting cells.

Rhesus Macaque CODEX Multiplexed Immunohistochemistry Panel for Studying Immune Responses During Ebola Infection

Non-human primate (NHP) animal models are an integral part of the drug research and development process. For some biothreat pathogens, animal model challenge studies may offer the only possibility to evaluate medical countermeasure efficacy. A thorough understanding of host immune responses in such NHP models is therefore vital. However, applying antibody-based immune characterization techniques to NHP models requires extensive reagent development for species compatibility. In the case of studies involving high consequence pathogens, further optimization for use of inactivated samples may be required. Here, we describe the first optimized CO-Detection by indEXing (CODEX) multiplexed tissue imaging antibody panel for deep profiling of spatially resolved single-cell immune responses in rhesus macaques. This 21-marker panel is composed of a set of 18 antibodies that stratify major immune cell types along with a set three Ebola virus (EBOV)-specific antibodies. We validated these two sets of markers using immunohistochemistry and CODEX in fully inactivated Formalin-Fixed Paraffin-Embedded (FFPE) tissues from mock and EBOV challenged macaques respectively and provide an efficient framework for orthogonal validation of multiple antibody clones using CODEX multiplexed tissue imaging. We also provide the antibody clones and oligonucleotide tag sequences as a valuable resource for other researchers to recreate this reagent set for future studies of tissue immune responses to EBOV infection and other diseases.

Highly Multiplexed Immunohistochemical MALDI-MS Imaging of Biomarkers in Tissues

Immunohistochemistry (IHC) combined with fluorescence microscopy provides an important and widely used tool for researchers and pathologists to image multiple biomarkers in tissue specimens. However, multiplex IHC using standard fluorescence microscopy is generally limited to 3-5 different biomarkers, with hyperspectral or multispectral methods limited to 8. We report the development of a new technology based on novel photocleavable mass-tags (PC-MTs) for facile antibody labeling, which enables highly multiplexed IHC based on MALDI mass spectrometric imaging (MALDI-IHC). This approach significantly exceeds the multiplexity of both fluorescence- and previous cleavable mass-tag-based methods. Up to 12-plex MALDI-IHC was demonstrated on mouse brain, human tonsil, and breast cancer tissues specimens, reflecting the known molecular composition, anatomy, and pathology of the targeted biomarkers. Novel dual-labeled fluorescent PC-MT antibodies and label-free small-molecule mass spectrometric imaging greatly extend the capability of this new approach. MALDI-IHC shows promise for use in the fields of tissue pathology, tissue diagnostics, therapeutics, and precision medicine.

Stem cell-derived CAR T cells traffic to HIV reservoirs in macaques

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) with CCR5^– donor cells is the only treatment known to cure HIV-1 in patients with underlying malignancy. This is likely due to a donor cell–mediated graft-versus-host effect targeting HIV reservoirs. Allo-HSCT would not be an acceptable therapy for most people living with HIV due to the transplant-related side effects. Chimeric antigen receptor (CAR) immunotherapies specifically traffic to malignant lymphoid tissues (lymphomas) and, in some settings, are able to replace allo-HSCT. Here, we quantified the engraftment of HSC-derived, virus-directed CAR T cells within HIV reservoirs in a macaque model of HIV infection, using potentially novel IHC assays. HSC-derived CAR cells trafficked to and displayed multilineage engraftment within tissue-associated viral reservoirs, persisting for nearly 2 years in lymphoid germinal centers, the brain, and the gastrointestinal tract. Our findings demonstrate that HSC-derived CAR⁺ cells reside long-term and proliferate in numerous tissues relevant for HIV infection and cancer.

Systematic evaluation of monoclonal antibodies and immunoassays for the detection of Interferon-γ and Interleukin-2 in old and new world non-human primates

Non-human primates (NHP) provide important animal models for studies on immune responses to infections and vaccines. When assessing cellular immunity in NHP, cytokines are almost exclusively analyzed utilizing cross-reactive anti-human antibodies. The functionality of antibodies has to be empirically established for each assay/application as well as NHP species. A rational approach was employed to identify monoclonal antibodies (mAb) cross-reactive with many NHP species. Panels of new and established mAbs against human Interferon (IFN)-γ and Interleukin (IL)-2 were assessed for reactivity with eukaryotically expressed recombinant IFN-γ and IL-2, respectively, from Old (rhesus, cynomolgus and pigtail macaques, African green monkey, sooty mangabey and baboon) and New World NHP (Ma's night monkey, squirrel monkey and common marmoset). Pan-reactive mAbs, recognizing cytokines from all NHP species, were further analyzed in capture assays and flow cytometry with NHP peripheral blood mononuclear cells (PBMC). Pan-reactive mAb pairs for IFN-γ well as IL-2 were identified and used in ELISA to measure IFN-γ and IL-2, respectively, in Old and New World NHP PBMC supernatants. The same mAb pairs displayed high functionality in ELISpot and FluoroSpot for the measurement of antigen-specific IFN-γ and IL-2 responses using cynomolgus PBMC. Functionality of pan-reactive mAbs in flow cytometry was also verified with cynomolgus PBMC. The development of well-defined immunoassays functional with a panel of NHP species facilitates improved analyses of cellular immunity and enables inclusion in multiplex cytokine assays intended for a variety of NHP.

Avoiding hepatic metastasis naturally: Lessons from the cotton top tamarin (Saguinus oedipus)

Much has been written about hepatic metastasis and animal models abound. In terms of the human experience, progress in treating this final common pathway, a terminal event of many human malignancies has been relatively slow. The current thinking is that primary prevention is best served by early detection of cancer and eradication of early stage cancers by screening. Some cancers spread early in their course and the role of screening may be limited. Until relatively recently there has not been a pathfinder model that makes the evasion of this unfortunate event a reality. This review discusses such an animal model and attempts to relate it to human disease in terms of intervention. Concrete proposals are also offered on how scientists may be able to intervene to prevent this deadly progression of the cancer process.

Comprehensive panel of cross-reacting monoclonal antibodies for analysis of different immune cells and their distribution in the common marmoset (Callithrix jacchus)

BACKGROUND

Common marmosets are extensively used in immunological and pharmacological research, and the usage of methods such as flow cytometry gain increasing importance.

METHODS

Using multicolor flow cytometry cross-reactivity of monoclonal antibodies with cells of common marmosets was analyzed. Furthermore, frequencies of immune cells and immunological parameters were assessed in healthy common marmosets.

RESULTS

A total of 97 clones of monoclonal antibodies raised against CD markers, chemokine receptors, and miscellaneous markers were tested. Additionally, baseline frequencies of different innate and adaptive immune cells as well as certain parameters, such as activation and memory T-cell and B-cell distribution, are provided.

CONCLUSION

Our study gives an extended overview of cross-reactive antibodies for flow cytometric analysis of immune cells as well as baseline values for different immune parameters in healthy common marmosets.

Morphology and staining behavior of neutrophilic and eosinophilic granulocytes of the common marmoset (Callithrix jacchus)

Common marmosets (Callithrix jacchus) are frequently used as translational animal models for human diseases. However, a comparative study of cytological and histochemical detection methods as well as morphometric and ultrastructural characterization of neutrophils and eosinophils in this species is lacking. Blood samples of house dust mite sensitized and allergen challenged as well as lipopolysaccharide (LPS) challenged marmosets were analyzed with different cytological and histological staining methods. Furthermore, cell size and number of nuclear segments were compared between neutrophils and eosinophils. Electron microscopy was performed to characterize the ultrastructure of granulocytes. Of all applied cytological stains, three allowed differentiation of eosinophils and neutrophils and, thus, reliable quantification in blood smears: May-Grünwald-Giemsa stain, Congo Red and Naphthol AS-D Chloroacetate-Esterase. For histology, Hematoxylin-Eosin (H&E) could not demonstrate clear differences, whereas Sirius Red, Congo Red, and Naphthol AS-D Chloroacetate Esterase showed capable results for identification of eosinophils or neutrophils in lung tissue. Morphometry revealed that marmoset neutrophils have more nuclear segments and are slightly larger than eosinophils. Ultrastructurally, eosinophils presented with large homogeneous electron-dense granules without crystalloid cores, while neutrophils were characterized by heterogeneous granules of different size and density. Additionally, sombrero-like vesicles were detected in tissue eosinophils of atopic marmosets, indicative for hypersensitivity-related piecemeal degranulation. In conclusion, we provide a detailed overview of marmoset eosinophils and neutrophils, important for phenotypic characterization of marmoset models for human airway diseases.

Exploring the innate immunological response of an alternative nonhuman primate model of infectious disease; the common marmoset

The common marmoset (Callithrix jacchus) is increasingly being utilised as a nonhuman primate model for human disease, ranging from autoimmune to infectious disease. In order to fully exploit these models, meaningful comparison to the human host response is necessary. Commercially available reagents, primarily targeted to human cells, were utilised to assess the phenotype and activation status of key immune cell types and cytokines in naive and infected animals. Single cell suspensions of blood, spleen, and lung were examined. Generally, the phenotype of cells was comparable between humans and marmosets, with approximately 63% of all lymphocytes in the blood of marmosets being T cells, 25% B-cells, and 12% NK cells. The percentage of neutrophils in marmoset blood were more similar to human values than mouse values. Comparison of the activation status of cells following experimental systemic or inhalational infection exhibited different trends in different tissues, most obvious in cell types active in the innate immune response. This work significantly enhances the ability to understand the immune response in these animals and fortifies their use as models of infectious disease.

Overview of models, methods, and reagents developed for translational autoimmunity research in the common marmoset (Callithrix jacchus)

The common marmoset (Callithrix jacchus) is a small-bodied Neotropical primate and a useful preclinical animal model for translational research into autoimmune-mediated inflammatory diseases (AIMID), such as rheumatoid arthritis (RA) and multiple sclerosis (MS). The animal model for MS established in marmosets has proven their value for exploratory research into (etio) pathogenic mechanisms and for the evaluation of new therapies that cannot be tested in lower species because of their specificity for humans. Effective usage of the marmoset in preclinical immunological research has been hampered by the limited availability of blood for immunological studies and of reagents for profiling of cellular and humoral immune reactions. In this paper, we give a concise overview of the procedures and reagents that were developed over the years in our laboratory in marmoset models of the above-mentioned diseases.

The development of small primate models for aging research

Nonhuman primate (NHP) aging research has traditionally relied mainly on the rhesus macaque. But the long lifespan, low reproductive rate, and relatively large body size of macaques and related Old World monkeys make them less than ideal models for aging research. Manifold advantages would attend the use of smaller, more rapidly developing, shorter-lived NHP species in aging studies, not the least of which are lower cost and the ability to do shorter research projects. Arbitrarily defining "small" primates as those weighing less than 500 g, we assess small, relatively short-lived species among the prosimians and callitrichids for suitability as models for human aging research. Using the criteria of availability, knowledge about (and ease of) maintenance, the possibility of genetic manipulation (a hallmark of 21st century biology), and similarities to humans in the physiology of age-related changes, we suggest three species--two prosimians (Microcebus murinus and Galago senegalensis) and one New World monkey (Callithrix jacchus)--that deserve scrutiny for development as major NHP models for aging studies. We discuss one other New World monkey group, Cebus spp., that might also be an effective NHP model of aging as these species are longer-lived for their body size than any primate except humans.