Changes in Cell Vitality, Phenotype, and Function of Dromedary Camel Leukocytes After Whole Blood Exposure to Heat Stress in vitro

Abstract

The dromedary camel (Camelus dromedarius) is well-adapted to the desert environment with the ability to tolerate increased internal body temperatures rising daily to 41–42°C during extreme hot. This study was undertaken to assess whether in vitro incubation of camel blood at 41°C, simulating conditions of heat stress, differently alters cell vitality, phenotype, and function of leukocytes, compared to incubation at 37°C (normothermia). Using flow cytometry, the cell vitality (necrosis and apoptosis), the expression of several cell markers and adhesion molecules, and the antimicrobial functions of camel leukocytes were analyzed in vitro. The fraction of apoptotic cells within the granulocytes, lymphocytes, and monocytes increased significantly after incubation of camel whole blood at 41°C for 4 h. The higher increase in apoptotic granulocytes and monocytes compared to lymphocytes suggests higher resistance of camel lymphocytes to heat stress. Functionally, incubation of camel blood at 41°C for 4 h enhanced the phagocytosis and ROS production activities of camel neutrophils and monocytes toward S. aureus. Monocytes from camel blood incubated at 41°C for 4 h significantly decreased their expression level of MHC class II molecules with no change in the abundance of CD163, resulting in a CD163high MHC-IIlow M2-like macrophage phenotype. In addition, heat stress treatment showed an inhibitory effect on the LPS-induced changes in camel monocytes phenotype. Furthermore, in vitro incubation of camel blood at 41°C reduced the expression of the cell adhesion molecules CD18 and CD11a on neutrophils and monocytes. Collectively, the present study identified some heat-stress-induced phenotypic and functional alterations in camel blood leukocytes, providing a paradigm for comparative immunology in the large animals. The clinical relevance of the observed changes in camel leukocytes for the adaptation of the camel immune response to heat stress conditions needs further in vitro and in vivo studies.

The Impact of Anticoagulation Agent on the Composition and Phenotype of Blood Leukocytes in Dromedary Camels

“…The comparable numbers of lymphocyte number as well as the numbers of their subsets in EDTA and heparin blood may be related to the higher resistance of camel lymphocytes to cell stress, which has recently been shown in a heat stress in vitro model [38]. This is also supported by the lack of effect of the two anticoagulants on lymphocyte necrosis or apoptosis.…”

Flow cytometric analysis of immune cell populations in the bronchial and mesenteric lymph nodes of the dromedary camel

“…Lymph node cells, blood MNC, or total leukocytes were labeled with monoclonal antibodies (mAbs) to camel leukocyte antigens and analyzed by flow cytometry ( 13 ). Separated cells (1 × 10 6 cells/well) were incubated in the wells of a 96-well plate with mAbs cross-reactive with the homologous camel molecules: CD45, CD44, BAQ44A, WC1, CD4, CD18, CD172a, CD14, CD163, and MHCII ( 15 , 16 ). After incubation (15 min; 4°C), cells were washed twice and were incubated with mouse secondary antibodies (IgM, IgG1, IgG2a; Invitrogen) labelled with different fluorochromes or with mouse isotype control antibodies (Becton Dickinson Biosciences).…”

Immunomodulatory Effects of the Cyclooxygenase Inhibitor Lornoxicam on Phenotype and Function of Camel Blood Leukocytes

“…PI-positive dead cells with permeable cell membranes were distinguished from PI-negative live cells. For the measurement of cell apoptosis, separated leukocytes (100µL in RPMI-1640 cell culture medium) were incubated with JC-1 (5,5 ,6,6 -tetrachloro-1,1 ,3,3tetraethylbenzimidazolcarbocyanine iodide) in a 96-well microtiter plate [27][28][29]. JC-1 solution (100µL of 2µmol/L final concentration) was added to the cells in each well for 15 min (5% CO2) at 37 • C. Finally, labeled cells were washed twice with PBS, suspended in 200µL PBS, and analyzed on the Acuri C6 flow cytometer (BD Biosciences).…”