B-1 cell (CD5+/CD11b+) numbers and nIgM levels are elevated in physically active vs. sedentary rats

Abstract

Habitual, moderate exercise is associated with improved health, including reductions in illness. These benefits may stem, in part, from immune function improvements. We have previously reported that daily wheel running increases serum and peritoneal natural IgM (nIgM) in pathogen-free Sprague-Dawely rats. B-1 cells, which primarily reside in the peritoneal cavity, produce nIgM in the absence of antigen stimulation. This study examined whether physical activity would also increase B-1 cell numbers in the peritoneal cavity, mesenteric lymph nodes, and spleen. Male, pathogen-free Fischer 344 rats were sedentary (standard cages) or physically active (running wheel access) for 6-7 wk. Peritoneal cavity, mesenteric lymph nodes, and spleen cells were taken, and the number of CD5+/CD11b+ (B-1) cells were measured by using two-color flow cytometry. The results were that physically active animals had increased numbers of CD5+/CD11b+ cells in the peritoneal cavity. In addition, physically active animals had increased serum and peritoneal nIgM, thus replicating our previous observations. These results indicate that voluntary running selectively increases the B-1 cell population, which is most likely responsible for the elevated serum and peritoneal nIgM in active rats. Because B-1 cells are important in host defense, these changes may contribute to the health benefits of exercise.

Exercise-induced B cell mobilisation: Preliminary evidence for an influx of immature cells into the bloodstream

“…'B1' cells are a population of B cells, originally identified in mice that produce high levels of low-affinity natural antibody. In rats, it has been shown that natural IgM and B1 cells are increased in physically active versus sedentary animals, but the effects of exercise in humans has remained unclear [11,12]. Recently, however, it has been shown that the phenotypic markers proposed for purported human 'B1' cells are, in fact, a population of pre-plasmablasts in humans [6].…”

CD11b-mediated migratory property of peripheral blood B cells

“…The B-1 cell is a subset of murine B cells and expresses CD11b. [16][17][18] They primarily reside in the peritoneal cavity and, by producing IgM, are known to play an important role in host defense. However, the B-cell system of human beings is known to be distinct from that of mouse or rat.…”

Athletes with higher VO2max present reduced oxLDL after a marathon race

“…Kyaw et al 43 44 showed the action of B1 cells in atheroprotective activity by the production of nIgM. Elphick et al 45 46 demonstrated, in an animal model, that training increases the production of nIgM. We observed that immediately after and up to 72 h after a marathon race, the levels of the IgM isotype anti-oxLDL autoantibodies remain unchanged, in contrast to the effect that would be expected if the autoantibody were acting to block the oxLDL.…”