Detection of Signal Regulatory Protein α in Saimiri sciureus (Squirrel Monkey) by Anti-Human Monoclonal Antibody.

Hugo Amorim Dos Santos De Souza,Cesare Bianco-Junior,Lilian Rose Pratt-Riccio,Paulo Renato Rivas Totino,Cláudio Tadeu Daniel-Ribeiro,Márcia Cristina Ribeiro Andrade,Josué Da Costa Lima-Junior,Edmar Henrique Costa-Correa

doi:10.3389/fimmu.2017.01814

Abstract

Non-human primates (NHP) are suitable models for studying different aspects of the human system, including pathogenesis and protective immunity to many diseases. However, the lack of specific immunological reagents for neo-tropical monkeys, such as Saimiri sciureus, is still a major factor limiting studies in these models. An alternative strategy to circumvent this obstacle has been the selection of immunological reagents directed to humans, which present cross-reactivity with NHP molecules. In this context and considering the key role of inhibitory immunoreceptors—such as the signal regulatory protein α (SIRPα)—in the regulation of immune responses, in the present study, we attempted to evaluate the ability of anti-human SIRPα monoclonal antibodies to recognize SIRPα in antigen-presenting S. sciureus peripheral blood mononuclear cells (PBMC). As shown by flow cytometry analysis, the profile of anti-SIRPα staining as well as the levels of SIRPα-positive cells in PBMC from S. sciureus were similar to those observed in human PBMC. Furthermore, using anti-SIRPα monoclonal antibody, it was possible to detect a decrease of the SIRPα levels on surface of S. sciureus cells after in vitro stimulation with lipopolysaccharides. Finally, using computed-based analysis, we observed a high degree of conservation of SIRPα across six species of primates and the presence of shared epitopes in the extracellular domain between humans and Saimiri genus that could be targeted by antibodies. In conclusion, we have identified a commercially available anti-human monoclonal antibody that is able to detect SIRPα of S. sciureus monkeys and that, therefore, can facilitate the study of the immunomodulatory role of SIRPα when S. sciureus is used as a model.

Highlights

Saimiri sciureus, known as squirrel monkey, is a small species of non-human primate natively found in the tropical rainforests of South America [1, 2]
Attempting to support further studies related to involvement of signal regulatory protein α (SIRPα) in immune responses, in the present work, we evaluated by flow cytometry if monoclonal antibody directed to human SIRPα cross-reacts with peripheral blood mononuclear cells (PBMC) from S. sciureus
Signal regulatory protein α is known as an immune inhibitory receptor present in leukocytes of the myeloid lineage and, it is expected that SIRPα in PBMC population is mainly detected on surface of cells showing monocyte morphology by size and granularity analysis in flow cytometry using forward scatter and sideward scatter parameters [30]

Summary

INTRODUCTION

Known as squirrel monkey, is a small species of non-human primate natively found in the tropical rainforests of South America [1, 2]. An alternative strategy to circumvent this limitation is the identification of immunological reagents directed to molecules of human immune system that present reactivity with S. sciureus. A variety of anti-human monoclonal antibodies commercially available are able to satisfactorily detect surface molecules of immune cells as well as cytokines of S. sciureus [12,13,14] and other non-human primate models, such as common marmoset (Callithrix jacchus), rhesus macaque (Macaca mulatta), and chimpanzee (Pan troglodytes) [15,16,17]. Attempting to support further studies related to involvement of SIRPα in immune responses, in the present work, we evaluated by flow cytometry if monoclonal antibody directed to human SIRPα cross-reacts with peripheral blood mononuclear cells (PBMC) from S. sciureus

MATERIALS AND METHODS

RESULTS AND DISCUSSION

ETHICS STATEMENT