Association of serum concentration of soluble class I HLA with HLA allotypes.

We correlated serum concentrations of soluble class I HLA antigens (S-HLA-I) with HLA allotypes in 82 unrelated Caucasian and 58 unrelated African-American putatively normal subjects, as well as in 31 individuals with stable, normally functioning liver transplants. Caucasian and African-American subjects with HLA-A23 or HLA-A24 were high secretors of S-HLA-I. We also observed that some HLA-A allotypes associated with high serum concentrations of S-HLA-I were ethnicity specific. HLA-A33 was associated with high S-HLA-I secretion in African-Americans but not in Caucasians. HLA-A29 was associated with high S-HLA-I secretion in Caucasians but not in African-Americans. All liver transplant recipients studied who were high secretors of S-HLA-I postoperatively carried HLA-A24 or HLA-A29. (There were no HLA-A33 or HLA-A23 allotypes in this group.) The "secretor genes," however, may be autogenous or allogenic (i.e., either donor or recipient HLA-A24 or HLA-A29 resulted in the observed high secretor status in liver transplant recipients after transplantation). It is noteworthy that serum S-HLA-I concentrations were low in all subjects with HLA-A2 regardless of whether the HLA-A2 was of recipient or donor origin. This finding suggests that HLA-A2 could have a suppressive effect on S-HLA-I secretion.