What do you really want to inhibit? Expression? Recognition by specific T cells? Recognition by all T cells? To inhibit expressionyou can use proteasome inhibitors like lactacystin: it is commercial, soluble in water but will affect the expression of all HLA alleles. To inhibit recognition by all T cells, there are blocking antibodies. To inhibit recognition by specific T cells, you could try design antagonist peptides by altering known TCR contacts in the antigen presented by HLA-B27 (not obvious...)
Mr. Hudrisier as HLA b27 is marker for spondylitis, so by supressing hla b27 either at transcriptional or translational level i want to attenuate inflamation in case of spondylitic patients