LAUSR

INTRODUCTION This study evaluated depression, monocyte phenotype, and immune function in physically active cannabis users. METHODS Participants (N=23) were classified as either cannabis users (CU, n=11) or non-users (NU, n=12). White blood cells isolated from blood were analyzed for co-expression of cluster of differentiation 14 (CD14) and 16 (CD16) using flow cytometry. Lipopolysaccharide (LPS) was cultured with whole blood and assessed for interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) release. RESULTS The percentage of white blood cells classified as monocytes was not different between groups; however, CU had a significantly greater percentage of monocytes classified as intermediate (p=0.02). When standardized per milliliter of blood, CU had significantly greater numbers of total monocytes (p=0.01), classical monocytes (p=0.02), and intermediate monocytes (p=0.01). Intermediate monocytes per milliliter of blood were positively correlated to the number of times CU used cannabis per day (r=0.864, p<0.01), and Beck Depression Inventory-II (BDI-II) score (r=0.475, p=0.03), which was significantly greater in CU (5.1±4.8) compared to NU (0.8±1.0; p<0.01). CU released significantly less TNF-α per monocyte in response to LPS. CONCLUSIONS Cannabis users had altered monocyte phenotypes and function compared to NU. Elevations in intermediate monocytes were positively correlated with measures of cannabis use and BDI-II score.