Phenotypic and Functional Heterogeneity of Bovine Blood Monocytes

Abstract

Murine and human peripheral blood monocytes are heterogeneous in size, granularity, nuclear morphology, phenotype and function. Whether and how bovine blood monocytes follow this pattern was analyzed in this study. Flow cytometrically, classical monocytes (cM) CD14+ CD16−, intermediate monocytes (intM) CD14+ CD16+ and nonclassical monocytes (ncM) CD14+ CD16+ were identified, with cM being the predominant subset (89%). cM showed a significant lower expression of CD172a, intM expressed the highest level of MHC class II molecules, and ncM were low positive for CD163. Compared to cM and intM, ncM showed a significantly reduced phagocytosis capacity, a significantly reduced generation of reactive oxygen species, and reduced mRNA expression of CXCL8, CXCL1 and IL-1β after LPS stimulation. Based on IL-1β secretion after LPS/ATP stimulation, the inflammasome could be activated in cM and intM, but not in ncM. IFNγ increased the expression of CD16 selectively on cM and induced a shift from cM into intM in vitro. In summary, bovine CD172a-positive mononuclear cells define three monocyte subsets with distinct phenotypic and functional differences. Bovine cM and intM share homologies with their human counterparts, whereas bovine ncM are not inflammatory monocytes.

Impacts of parturition and body condition score on glucose uptake capacity of bovine monocyte subsets

“…Therefore higher glucose uptake capacities of bovine cM and intM are in line with their abilities to defend invading pathogens and might "fuel" their performance. The discrepancy in glucose uptake of human and bovine ncM reflects species differences already mentioned by Hussen et al (2013). While human ncM are part of the proinflammatory CD16+ subset (Belge et al, 2002), the distinct functions of bovine ncM are unknown at the moment.…”

“…The difference in glucose uptake of bovine monocyte subsets might correlate with their functional activities. In cattle cM display the highest phagocytotic capacity and intM are the main producers of ROS and proinflammatory cytokines, whereas ncM show only marginal phagocytosis and ROS production (Hussen et al, 2013). Activation of immune cells is associated with increased energy needs and a switch of cell metabolism to glycolysis (Dietl et al, 2010).…”

“…Based on their expression of CD14 and CD16, monocytes are classified as classical monocytes (cM, CD14+CD16−), intermediate monocytes (intM, CD14+CD16+) and nonclassical monocytes (ncM, CD14−CD16+) (Hussen et al, 2013). Although this classification system and phenotypic characteristics are quite close to the human system (Hussen et al, 2013;ZieglerHeitbrock et al, 2010), differences in functional properties have been reported (Hussen et al, 2013(Hussen et al, , 2014. Since the functional importance of the three monocyte subsets has not fully been clarified in cattle it was the aim of the present study to evaluate whether prepartal differences in BCS may influence blood monocyte subset composition and glucose uptake capacity of monocyte subsets during the peripartal period.…”

Reactivity of commercially available monoclonal antibodies to human CD antigens with peripheral blood leucocytes of dromedary camels (<i>Camelus dromedarius</i>)

“…The higher staining intensity of human and camel granulocytes and monocytes with the mAb 557743 (clone ICRF44) specific for human CD11b and the weaker staining of lymphocytes indicates that this mAb recognizes CD11b in both species. CD14 is a co-receptor for bacterial lipopolysaccharides and is mainly expressed on blood monocytes (Hussen et al, 2013). Three clones of antibodies specific to human CD14 have been tested for cross-reactivity with camel leukocytes.…”

“…In comparison to several other veterinary species like cattle (Hussen et al, 2013;Duvel et al, 2014), pigs (Gerner et al, 2015), sheep and horses (Lunn et al, 1998), the immune system of camels remains to a great extent poorly studied. Although considerable progress has been made in the characterization of camel immunoglobulins (HamersCasterman et al, 1993;Muyldermans, 2013), few data are available on the cellular immunity of camels in health or disease (Zidan et al, 2000a,b;Al-Mohammed Salem et al, 2012).…”