SEROTYPING FOR HOMOTRANSPLANTATION .23. ANALYSIS OF KIDNEY TRANSPLANTS FROM PARENTAL VERSUS SIBLING DONORS

The role of HL-A antigen compatibility in the clinical outcome of kidney transplantation was studied in 107 sibling to sibling and 147 parent to child transplants. As could be predicted on genetic grounds, certain sharp differences between the two genetic classes of donors were found. Leukocyte matching was highly significantly correlated with the clinical outcome and survival among sibling transplants. Of the five antigenic specificities examined, all were statistically significant in influencing the outcome of transplantation among siblings. Among parent to child transplants the data were significant, although somewhat less significant than in sibling transplants. Antigenic groups HL-A1 and HL-A7 were somewhat weaker than the others with parental grafts. A cumulative effect of several antigens was not apparent. The lower correlation for the parental donor grafts was not primarily produced by undetected antigens causing rejection, but rather by survival with good function in spite of incompatibilities. An explanation was sought for the excessive rate of parental graft success. Age of the recipient and the donor did not significantly influence the survival of the mismatched parental grafts. Tolerance to the maternal graft was not the explanation, since mismatched paternal grafts survived as well as mismatched maternal grafts. If the locus is to be considered the principal histocompatibility locus in man, it is clear that with kidney transplantation utilizing current immunosuppressive therapy an incompatibility for a single allele having any of the five antigens studied is not invariably deleterious. Thus HL-A antigens are not “strong” antigens but rather can be more conveniently thought of as “intermediate” in strength. 1969 Williams and Wilkins Co.