Notably, it has been reported that B cell depletion after treatment with rituximab in autoimmune disorders affects T cell differentiation and activation, including down-regulation of costimulatory molecules and activation markers (eg, CD44, CD40L, CD69, HLA-DR, ICOS) on CD4+ T cells, and increases in regulatory T cell numbers and suppressive functions27. Here, ICOS is linked to autoimmune disease.