Identification and functional analysis of NKp46+ natural killer cells from peripheral blood of squirrel (Saimiri sps.) and owl monkey (Aotus sps.)

Abstract

Abstract Natural Killer (NK) cells as minor subsets of peripheral blood lymphocytes (PBL) are innate in nature to clear invading pathogens and tumor cells. Small rodent species to nonhuman primates and humans, immune systems consist of a spectrum of NK cell subsets with phenotype and functional diversity. This study examined NK cell subsets and expression of NKp46 in squirrel and owl monkeys, which are both New World primate species. Squirrel and owl monkeys are recommended by the World Health Organization as excellent experimental models for studies of malaria infection due to their susceptibility to some of the same strains that cause disease in humans and endemic viruses that are analogues of opportunistic human viruses. NK cells were identified from CD3 negative lymphocytes and sub-phenotyped by CD16 and CD8 expression, to classify CD8+ and CD8− NK cells and absolute numbers in peripheral blood were compared. Analysis of expression of NCR (Natural Cytotoxicity Receptors) proteins, NKp30 and NKp46 showed that NK cells from NHP had preferential expression of NKp46 over NKp30 and expression is mostly restricted to subset of CD8+ NK cells. Peripheral blood lymphocytes, enriched based on NKp46 expression, were further phenotyped as classic CD3−CD16+CD8+NK cells. Functional analysis of enriched cells was focused to verify whether subsets differ in cytolitic and/or “innate” in nature and to correlate with NCR protein expression. Enriched NK cells were co-cultured for stimulation with standard target cells including tumor cells and analyzed for cytokine production. The potential plasticity of peripheral blood NK cells in NHP based on steady state and/or inflammatory/pathogenic status of species will be analyzed and discussed.