To further investigate whether B cells from HSP controls also showed the immunophenotypic changes observed in cKS patients indicative for a state of lower activation, we analyzed B cell expression of CD80 and CD86 and observed indeed that the intensity of expression of both costimulatory molecules, expressed as MFI, was significantly lower on B cells from HSP than HCs (P<0.02 and P<0.05 for CD80 and CD86, respectively) (Table 1). This evidence concerns the gene CD80 and hereditary spastic paraplegia.