Expression of human flCTLA-4, sCTLA-4 and ICOS mRNA does not correlate with CT60 genotype. Expression was measured by real-time quantitative PCR of RNA purified from CD4+ T cells of 23 healthy volunteers. RPL13 was used as an endogenous control. Error bars represent SD. Black, white and grey bars represent flCTLA-4, sCTLA-4 and ICOS mRNA expression respectively.