Photopheresis Found to Treat GvHD By Favorably Altering WBC Profile

While allogeneic hematopoietic stem cell (HSC) transplantation is intended to combat cancers of the blood or bone marrow such as leukemia and multiple myeloma, the procedure carries the risk of graft-versus-host disease (GvHD), a damaging and potentially life-threatening complication in which donor-derived immune cells proliferate and attack the recipient.

GvHD occurs acutely (aGvHD) and chronically (cGvHD), developing during or after the first 100 days post-transplantation, respectively.

Previous studies have shown that a population of white blood cells known as Natural Killer cells (NK cells) are important mediators of GvHD and that NK cells expressing high levels of the cell surface receptor protein CD56 are particularly involved in steroid-refractory and/or resistant GvHD following allogeneic HSC transplantation.

Ni et al explored whether aGvHD patients, cGvHD patients, and healthy controls carried different NK cell populations in the peripheral blood, checking for the expression of CD56 and other markers associated with disease outcome.

These patient populations were indeed shown to have distinct NK cell profiles. aGvHD patients beared higher levels of CD56+ NK cell subsets while NK cells were predominantly CD56- in cGvHD patients.

The researchers demonstrated that a current treatment for GvHD, extracorporeal photopheresis, may function by reducing the frequency of CD56+ NK cells in the blood, shifting the immune cell profile from destructive to immunosuppressive.

Notably, this therapy altered the distribution of NK cell subsets without disrupting the anti-cancer effect of HSC transplantation and may represent a promising supplement or alternative to standard steroid-based treatment.

Ni M, Wang L, Yang M, et al. (2019) Shaping of CD56bri Natural Killer Cells in Patients With Steroid-Refractory/Resistant Acute Graft-vs.-Host Disease via Extracorporeal Photopheresis. Frontiers in Immunology.

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