Incidence of humoral sensitization in HLA partially mismatched hematopoietic stem cell transplantation.
As part of the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), seven centers participated in a collaborative project to determine whether any significant humoral sensitization occurred post-transplant among recipients of HLA partially mismatched hematopoietic cell transplants (HCTs). A total of 140 donor/recipient pairs were enrolled with a total of 367 pre-and post-transplant sera analyzed. The majority of the samples (69.1%) were obtained within 30-90 days post-HCT. HLA-specific antibodies were defined using single antigen bead assays on a Luminex platform with a positive cutoff value of 1000 normalized median fluorescence intensity (MFI). There was an overall incidence of post-HCT sensitization toward donor HLA mismatches of 5.7%; however, all cases were among recipients of one HLA haplotype-mismatched grafts under nonmyeloablative, pre-transplant conditioning. Among the one haplotype-mismatched recipients, 15.7% (8/51) developed donor HLA-specific antibodies and 29.4% also had antibodies directed toward third party HLA antigens. Among the donor-specific antibodies, 9.8% were directed toward HLA class I antigens; 7.8% were against class II antigens; and 2.0% had both class I and II specificity. The relative strength of post-transplant antibodies was low with no significant difference in the mean maximum MFI values between third party and donor-specific antibodies. Because only a small number (10.2%) of the post-transplant samples were obtained 180 days or more post-HCT, longer term study is needed to evaluate any clinical relevance of these low-to-moderate levels of donor-specific antibody in one haplotype-mismatched recipients, as well as to determine whether any other antibodies occur at later times.
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. msl@jhmi.edu
M S
MS
Leffell
K
K
Cao
M
M
Coppage
J A
JA
Hansen
J M
JM
Hart
N
N
Pereira
S
S
Pereira
N L
NL
Reinsmoen
D
D
Senitzer
A
A
Smith
M
M
Torres
R
R
Vega
E
E
Fuchs
D006084:Graft Rejection / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology*; D018380:Hematopoietic Stem Cell Transplantation; D006650:Histocompatibility Testing; D006801:Humans; D014019:Tissue Donors
D006680:HLA Antigens