Measurement of cytotoxic T lymphocyte precursor frequencies reveals cryptic HLA class I mismatches in the context of unrelated donor bone marrow transplantation.
BACKGROUND
In this large, two-center study, 260 cytotoxic T lymphocyte precursor (CTLp) frequency assays, performed to assess patient-donor compatibility, were analyzed in relation to the degree of HLA matching.


METHODS
While the tissue-typing techniques used at the Royal Postgraduate Medical School (RPMS) and Anthony Nolan Bone Marrow Trust (ANBMT) differ, the results of the analyses on the two sites are analogous, with high CTLp frequencies (>1:100,000) in 42% and 41% of recipient-donor pairs, respectively.


RESULTS
Recipient-donor combinations with class I mismatches and class II identity were associated with high CTLp frequencies (collectively 83% vs. 17% low CTLp). This correlation was not as strong in pairs where class II mismatches were demonstrated (61% high vs. 39% low). Despite using different matching procedures, the RPMS and ANBMT both show that 32% of the "perfectly" matched pairs (i.e., where no mismatch was detected by any of the techniques used here) had high frequencies of recipient-specific CTLp.


CONCLUSIONS
The failure of conventional methods to identify such a level of histoincompatibilities indicates that the CTLp assay has an important role in the selection of unrelated donors for bone marrow transplantation.
O'Shea
J
J
Anthony Nolan Bone Marrow Trust, Royal Free Hospital, London, England.
Madrigal
A
A
Davey
N
N
Brookes
P
P
Scott
I
I
Firman
H
H
Lechler
R
R
Goldman
J
J
Batchelor
R
R
D016026:Bone Marrow Transplantation / Q000276:immunology*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007525:Isoelectric Focusing; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000276:immunology; D014019:Tissue Donors
D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II