HLA‐DP incompatibilities induce significant proliferation in primary mixed lymphocyte cultures in HLA‐A, ‐B, ‐DR and ‐DQ compatible individuals: Implications for allogeneic bone marrow transplantation

Abstract

The major part of the proliferative response in primary mixed lymphocyte cultures (MLC) is caused by HLA-DRB1 incompatibilities. In DRB1-matched pairs the proliferation induced by HLA-DRB3, -DQ and -DP mismatches may be unmasked. In most previous studies the influence of HLA-DP incompatibilities in primary MLC has been investigated in homozygous typing cells representing only a few Dw specificities. We were interested in determining the stimulatory capacity of isolated HLA-DP mismatches, ascertained by RFLP analysis, in primary MLC in HLA-A, -B, -DR and -DQ compatible, unrelated heterozygous individuals of many different Dw specificities. Thirty-eight MLCs performed with cells from related pairs and 67 with cells from unrelated pairs were evaluated. All but nine of the MLCs were analyzed in both directions, giving a total of 201 investigated reactions. The relative responses (RR) in the three MLCs performed between DP incompatible, related pairs were all positive (RR greater than or equal to 8%). Eighty of 82 MLCs performed with cells from DP incompatible, unrelated individuals were positive, whereas 37 of 46 MLCs between DP compatible, unrelated pairs were negative (RR less than 8%) (p less than 10(-10)). The magnitude of the RR was influenced by the number of DP mismatches. Thus, the mean RR was approximately twice as high in MLCs in which responder and stimulator cells differed by two DP antigens (mean RR 60.5%) compared with reactions with only one DP mismatch (mean RR 35.4%) (p less than 10(-3)). RFLP-defined HLA-DP incompatibilities predict a positive primary MLC in HLA-A, -B, -DR and -DQ matched individuals with a high degree of accuracy (98%).(ABSTRACT TRUNCATED AT 250 WORDS)

The importance of HLA-DPB1 in unrelated donor hematopoietic cell transplantation

“…Traditional methods for typing HLA-DP gene products include the primed lymphocyte test, a modified mixed lymphocyte culture method in which 6 alloantigens could be distinguished. 28,29 The extensive sequence polymorphism of this locus mandated the use of modern DNA-based methods to uncover undetected donor-recipient disparity (http:// www.ebi.ac.uk/imgt/hla/stats.html). 12 In addition, it was shown that while much of the MHC displays strong positive linkage disequilibrium (LD; where certain alleles are seen together at a higher frequency than would be predicted by chance), LD weakens between HLA-DQB1 and HLA-DPB1, resulting in a high incidence of mismatching for DPB1 5,14,30 and a low chance of identifying DPB1-matched donors even when there is matching for other HLA genes.…”

Significantly higher frequencies of alloreactive CD4+ T cells responding to nonpermissive than to permissive HLA-DPB1 T-cell epitope disparities

“…7,8 Interestingly, Rutten and colleagues observed high levels of cytokine production by CD4 ϩ T cells in response also to autologous DP molecules presumably presenting minor histocompatibility antigens, 5 suggesting that the HeLa cell transfectants expressing DP but not other class II antigens used in their experiments may not quantify physiologic frequencies of alloreactive T helper cells, which increase substantially with the number of mismatched HLA-DP alloantigens in classical in vitro assays. 9,10 Here, we have quantified the frequency of alloreactive CD4 ϩ T cells responding to permissive or nonpermissive TCE3 or TCE4 DP mismatches, in classical MLRs between peripheral blood mononuclear cells (PBMCs) of responder (R)-stimulator (S) pairs matched for 10/10 of the non-DPB1 alleles. When S presented both a permissive and a nonpermissive mismatch, the percentage of responding CD4 ϩ T cells was more than 10-fold higher against the nonpermissive (DPB1*09:01, 10.65%) compared with the permissive mismatch (DPB1*04:02, 0.88%; Figure 1A), and this result was highly reproducible in 3 independent experiments (data not shown).…”

Positive Mixed Lymphocyte Culture Test Result Due To Hla –dp Mismatch

“…Akraba olmayan grupta MLC testi yapılan vakalarda pozitif sonuçların az olmasının sebebini de kabul edilen yüksek RRI değerlerinden kaynaklanmış olabileceğini belirtmişlerdir. Ayrı-ca bu çalışmada iki DP uyumsuzluğu olan hasta verici çiftlerin-de, tek DP uyumsuzluğuna göre RRI değerlerinde daha fazla artış olduğu görülmüştür (8). Vakamızdaki DP uyumsuz akraba çiftin MLC sonucunun pozitif bulunması Olerup ve ark.…”