Eight Weeks of Daily Cannabidiol Ingestion Does Not Alter Peripheral Blood Mononuclear Cell Profile or Natural Killer Cell Cytotoxicity

Abstract

ObjectiveThe purpose of this randomized placebo‐controlled trial was to determine the effects of an 8‐week cannabidiol (CBD) intervention on peripheral blood mononuclear cells (PBMCs) profile and natural killer cell (NKC) cytotoxicity.HypothesisFollowing an 8‐week CBD intervention, participants consuming CBD will have an increased percentage of NKC in peripheral blood, as well as decreased NKC cytotoxicity determined by a measure of K562 cell viability.MethodsPhysically active men and women (18‐45 y), currently meeting the American College of Sports Medicine (ACSM) guidelines for physical activity were randomly assigned to placebo (CN, n=5) or CBD (CB, n=9) groups. Participants consumed capsulized control; coconut derived medium chain triglycerides (MCT; 225mg/day) or CBD (50mg/day with 175mg of MCT) daily for 8 weeks. Participants completed measures of body size, body composition (BodPod) and fitness (VO2max), and peripheral blood was drawn before and after the intervention. Ficoll‐isolated PBMCs were co‐incubated for 4h with K562 human leukemia cells before cytotoxicity analysis by flow cytometry. Before co‐culture, PBMCs were stained with T cell marker CD3, and NKC marker, CD56, for immune profiling. K562 cells were pre‐stained with cell‐specific CD71 (transferrin receptor) and the cell viability dye Calcein AM. Data are presented as mean ± standard deviation with significance set at a=0.05. At the pre intervention time point, data was not normally distributed, so a Welch’s t‐test was preformed to determine group differences. A 2 (group) x 2 (time) analysis of variance (ANOVA) was used to identify any interactions or main effects.ResultsAt the pre‐intervention time points, there were no significant differences between groups with respect to participant characteristics (age: 27.1 ± 6.1 y; height: 169 ± 9.7 cm; weight: 73.8 ± 15.5 kg; lean body mass: 57.5 ± 12.0 kg; body fat: 21.5 ± 8.3%; VO2Peak: 45.2 ± 7.6 ml/kg/min). There were no significant differences in percentage of NKC (Pre: 8.8 ± 5.8%; Post:7.4 ± 5.7%), natural killer T‐cells (NKT; Pre: 1.7 ±1.1; Post: 1.5 ±1.1%), or T‐cells (Pre: 47.37±13.3; Post: 46.29±10.17%) when CN was compared to CB following the intervention. Furthermore, there were no differences in K562 cell mean or median fluorescence intensity of Calcein AM when CN was compared to CB following the intervention.ConclusionEight weeks of CBD (50mg/day) did not alter NKC, NKT, or T‐cell distribution in PBMCs. In line with these findings, NKC showed similar cytolytic function through no change in mean or median fluorescence intensity of Calcein AM expression of K562 human leukemia cells, indicating no change in cell viability following CBD supplementation. This preliminary study suggests that CBD does not alter the distribution of circulating mononuclear immune cells or NKC cytolytic function.