Western blotting analysis of plasma fractions prepared from plasmapheresis eluates obtained from different patients with post-transplant recurrence of FSGS revealed the presence of two bands, at 17 and 34 kDa, identical to those of human recombinant sCD40L, which correspond to the monomeric and dimeric forms of sCD40L (Fig 7). The gene discussed is CD40LG; the disease is focal segmental glomerulosclerosis.