Immune cell redistribution after vascularized bone marrow transplantation

Abstract

The specificity of a limb transplant lies in its anatomy. It is a graft of an organ, in analogy to the kidney or heart transplant, but in addition, it is a graft of bone marrow (BM) whose cells (BMC) do not only proliferate and mature in the graft but also migrate to the recipient bone marrow cavities and lymphoid organs (LO). Thus, the immune contact between the donor and recipient takes place not only in the graft itself but also in the recipient's immune organs, where the released BMC home. The BMC released from the graft may also home in other tissues, especially those with direct contact with environment as skin, gut, and lungs. Interestingly, there have been reports that the donor bone marrow cells may survive in the allogeneic recipient and create a state of cellular microchimerism. Microchimerisms are, according to some researchers, linked with the development of partial tolerance to donor alloantigens. This is a controversial issue with a number of observations supporting and negating the concept of microchimerism as a causative factor in prolongation of survival of organ allograft transplanted concomitantly with bone marrow. Another problem is the graft-versus-host reaction developing after bone marrow transplantation. There are reports providing evidence for lack of the graft-versus-host reaction after limb transplantation.