B cell subset distribution in human bone marrow is stable and similar in left and right femur: An instructive case.

The bone marrow (BM) is, in addition to being the site of B cell development, a tissue that harbors long-lived plasma cells (PC), the cells that protect the body against foreign antigens by continuous production of antibodies. Nothing is known about the long-term stability and functionality of both B cells and PC in the BM at the individual donor level since repeated sampling possibilities outside of oncology are scarce. Here, we had the opportunity to obtain BM samples from a patient undergoing bilateral total hip arthroplasty half a year apart. We observed that the frequencies of the analyzed B cell and PC subsets were similar despite a time of six months in between and sampling on left and right side of the body. Additionally, B cell receptor stimulation led to comparable results. Our data suggest that composition and functionality of B cells are stable in the BM of adults at the individual donor level.