Pregnancy can induce long-persisting primed CTLs specific for inherited paternal HLA antigens

Previous studies showed that pregnancy can prime the maternal cellular immu ne response directed against paternal HLA antigens. Primed CTLs specific fo r inherited paternal HLA antigens (IPA) were found in women who had formed HLA allo antibodies, whereas naive CTLs were present in women who did nor f orm antibodies against the paternal HLA antigens. As HLA allo antibodies ma y disappear in rime, it is not clear which women on the waiting list for tr ansplantation have been sensitized to paternal HLA antigens and are at risk for graft rejection if paternal HLA antigens are shared by the donor organ . The presence of primed CTLs specific for a particular antigen is consider ed to be a reflection of sensitization. In the present study we investigate d whether these primed CTLs persist in women who had been pregnant and had formed antibodies against the inherited paternal HLA class I antigens. For this purpose 14 women who had their last pregnancy 10 years ago were analyz ed with respect to IPA-specific CTLp frequencies and the presence of high a vidity CTLs directed against inherited paternal HLA class I antigens. Altho ugh primed CTLs specific for IPA's were found more frequently in women with persisting alloantibodies, they still can be detected when the antibodies have dis appeared. The current data show that primed CTLs directed against inherited paternal HLA antigens towards which antibodies have been formed i n the past can persist for more than 10 years after pregnancy. The cellular test used in our study can be useful to detect presensitization in women w ith a history of pregnancy, who enter the waiting list for transplantation. (C) American Society for Histocompatibility and Immunogenetics, 2001. Publ ished by Elsevier Science Inc.