CD8A and progressive multifocal leukoencephalopathy: On the other hand, in case 2, the patient underwent allogeneic HSCT, thus with a much deeper immunological suppression, supported by previous conditioning regimen, steroid treatment and an unbalanced T-cell count (CD4 + 97/mm3, CD8 + 730/mm3) which led to a thriving PML infection and a rapid progressive disease.