This 2021 rodent study investigated sulforaphane’s adaptive immune system effects on arthritis:

“Sulforaphane reduced clinical and histologic scores of collagen-induced arthritis mice. Anti-arthritic and anti-inflammatory effects of sulforaphane were due to suppression of differentiation of naïve cells into plasma cells and GC [germinal center] B cells.

This is the first report that sulforaphane exerts an anti-arthritic effect by regulating B-cell differentiation. Because plasma cells are not affected by conventional immunosuppressive drugs such as steroids, cyclophosphamide, and B-cell-depleting agents, our finding that sulforaphane suppresses their differentiation into plasma cells is encouraging and suggests that plasma cell-targeted treatment strategies for rheumatoid arthritis may be effective.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7886167/ “The anti-arthritis effect of sulforaphane, an activator of Nrf2, is associated with inhibition of both B cell differentiation and the production of inflammatory cytokines”

Although not directly stated, it appeared that this study had 15 sulforaphane treatment subjects from the same experiments being run 3 times on 5 subjects. The above graphic was repeated with the other two less-significant findings in supplementary data.