A preliminary study suggests Black people who have multiple sclerosis and neuromyelitis optica spectrum disorder, may respond differently than white people to a common therapy meant to modulate the immune system.

The people in this study were given anti-CD20 infusion therapies, which are often used to treat autoimmune diseases such as MS and neuromyelitis optica spectrum disorder, which is a relapsing inflammatory disorder of the optic nerve, spinal cord, and brain. The goal of this treatment, called B-cell depletion therapy, is to destroy B-cells in blood circulation. B-cells are partly responsible for the abnormal autoimmune responses in people with MS and NMOSD.

The study involved 168 people, 134 with MS and 32 with neuromyelitis optica spectrum disorder. The group included 61 who identified as Black and 60 who identified as white. The people received infusions of the drugs rituximab or ocrelizumab. Between four and six months after their infusions, Black and white people showed no difference in the levels of B-cells that could be measured in their blood samples.

However, when researchers looked at B-cell levels between six and 12 months after people received their blood infusions, there was a difference. Sixteen out of 21, or 76 percent, of the Black people had detectable levels of B-cells, compared to four out of 12 white people, or 33.3 percent.

A limitation of the study is researchers analyzed the available results at different times after infusion, rather than making measurements at the same specified times in all patients. More research is needed to determine whether faster return of B-cells in Black people means they are more likely to have more disease activity.

The research will be presented at the American Academy of Neurology's 73rd Annual Meeting.