In vitro immunogenicity of allogeneic cardiac valves

The immunogenicity of allogeneic cardiac valves (ACV) has not been previously demonstrated in vitro, though valve failure due to tissue degeneration has been attributed to adverse immunological reactions. A novel in vitro assay has been developed in a Brown Norway (BN; RT1n)-Lewis (RT1; donor-recipient) rat model system that demonstrates the immunogenicity of ACVs. A single cell suspension of viable cardiac valve conduit (CVC) cells was obtained by collagenase treatment of BN rat aortic valve conduits. Brown Norway rat CVC cells (5 x 10(4)) and Lewis responder lymphocytes (10(5)) were co-cultured in 96 well plates in RPMI 1640 plus 2.5% (v/v) non heat-inactivated Lewis rat serum and supplements with appropriate controls. Stimulation of responder lymphocytes by CVC cells was measured by 3H-thymidine incorporation into DNA. The counts obtained between 96-192 h of co-culture in the CVC cell/responder lymphocyte reaction were significantly higher (P < 0.05) than those of responder cell controls as assessed by analysis of variance. These results indicate the presence of potent immunostimulatory cells in viable ACVs and the possibility of using a sensitive and reproducible in vitro assay to evaluate ACV immunogenicity.