CD8A and diabetes mellitus: A role for B cell activation of CD8+ T cells has also been suggested since B cell-deficient NOD.Igμnull mice reconstituted with NOD B cells expectedly develop disease, but reconstitution with B cells from NOD.β2m-/- mice does not induce diabetes (β2 microglobulin is an essential component of MHC-I class molecules) (228).