Philip A. Dyer

Posttransplantation production of donor HLA-specific antibodies as a predictor of renal transplant outcome

Background. This study aimed to determine whether the production, in renal transplant recipients, of antibodies directed against donor HLA mismatches is predictive of transplant failure. Methods. The failure study group comprised 112 adult recipients of primary renal transplants who had re-entered the transplant waiting list after failure of the first graft. A control group of 123 recipients with functioning transplants was selected from transplantations performed during the same time period, in which patients had equivalent HLA matching and immunosuppression and a minimum of 5 years of follow-up. Sera taken before transplantation and at 1, 3, and 6 months and annually after transplantation were tested by enzyme-linked immunoabsorbent assay (ELISA) for the presence of HLA class I- and class II-specific antibodies. Antibody specificity was defined by a combination of cytotoxicity, ELISA, and flow cytometry techniques to determine whether the antibodies were directed against donor mismatches. Results. All recipients were negative for donor HLA-specific antibodies before transplantation. After transplantation, 57 (50.9%) of the 112 patients in the failure group produced donor HLA-specific antibodies compared with 2 (1.6%) of the 123 controls (P <0.0001; odds ratio [OR]=64.98; confidence interval [CI], 14.78–399.51). For 60% of the donor-specific antibody-positive patients, antibodies were detected before transplant failure. In 17 cases, these were class I specific; in 14 cases, class II specific; and in 3 cases, specific for both class I and II. Conclusions. This study has demonstrated that the production of posttransplantation antibodies directed against donor HLA-A, -B, -Cw, -DR, and -DQ mismatches are all strongly predictive of transplant failure.

Cytokine gene polymorphism and heart transplant rejection

BACKGROUND Allograft rejection is mediated by cytokines. As polymorphism in cytokine genes can result in interindividual differences in cytokine production, we hypothesize that some patients may have an increased risk of rejection. METHODS We have related polymorphisms that influence cytokine production in the tumor necrosis factor (TNF)-A and interleukin (IL)-10 genes to early graft rejection in 115 heart transplant recipients. RESULTS Certain combinations of TNF-A and IL-10 gene polymorphisms are associated with rejection. Five of 19 patients who had high levels of rejection typed as high TNF-alpha/low IL-10 producers compared with 4 of 96 patients with lower levels of rejection (P<0.005). CONCLUSIONS We have identified a particular cytokine genotype that may confer susceptibility to increased levels of early rejection. Patients with a worse prognosis may be able to be identified pretransplant by DNA analysis of TNF-A, IL-10, and other gene polymorphisms.

Frequency of down-regulation of individual HLA-A and -B alleles in cervical carcinomas in relation to TAP-1 expression

The development of cervical carcinoma is strongly associated with specific types of human papillomaviruses (HPVs). A role for cellular immunity in cervical disease is supported by the increased occurrence of HPV-associated lesions in immunosuppressed individuals. Upon viral infection or malignant transformation, ensuing alterations in gene expression result in the generation of novel sets of peptides which can form complexes with specific HLA class I heavy chains and beta 2-microglobulin. These are then expressed at the cell surface as potential targets for specific T cells. In this study of 100 carcinomas HLA-A and -B class I expression by the tumour cells was down-regulated at one or more alleles in at least 73% of cervical carcinomas. Interference with the transporter associated with antigen presentation (TAP), which translocates cytosolic peptides from endogenously synthesised proteins (e.g. viral) into the lumen of the endoplasmic reticulum was found in 38% of the HLA class I down-regulated tumours. Loss of expression for common HLA class I alleles ranged from 36% to 71%, and such changes might be expected to influence specific immunogenic peptide presentation and consequent immune recognition. These results underline the importance of single as well as multiple allelic loss in cervical neoplasia and have important implications for attempts to intervene immunologically in cervical cancer.

HPV 16 infection and progression of cervical intra‐epithelial neoplasia: Analysis of HLA polymorphism and HPV 16 E6 sequence variants

High‐risk human papillomavirus (HPV) infection plays an important role in cervical intra‐epithelial neoplasia (CIN), but HPV infection alone is not sufficient for progression to cervical cancer. Several lines of evidence suggest that cellular immune surveillance is important in the control of HPV infection and the development of CIN. The presentation to T cells of target viral peptides in the context of HLA molecules is influenced by the genetic polymorphisms of both HPV and HLA and thereby influences the host immune response and clinical outcome of HPV infection. HLA class I and II polymorphism in susceptibility for HPV 16 infection, development and progression of CIN was analyzed in a group of 118 patients participating in a prospective study of women with initial abnormal cytology. Patients were stratified according to HPV status and course of the disease. HLA‐B*44 frequency was increased in the small group of patients with a lesion that showed clinical progression during follow‐up [OR = 9.0 (4.6–17.5),p= 0.007]. HLA‐DRB1*07 frequency was increased among HPV 16‐positive patients compared with patients who were negative for all HPV types [OR = 5.9 (3.0–11.3), p= 0.02]. Our results are consistent with the immunogenetic factors associated with disease progression being different from those associated with susceptibility to HPV 16 infection. Sequencing of the HPV 16 E6 and E7 open reading frames of a subset of these patients (n = 40) showed the frequency of HPV 16 variants to be similar to other studies. However, there was no significant correlation between variant incidence and disease progression or viral persistence and no significant correlation with any HLA allele. It appears that multiple HLA types can influence HPV 16‐associated cervical dysplasia but the role of HPV 16 variants in disease progression and susceptibility in relation to HLA polymorphism remains unclear. Int. J. Cancer 78:166–171, 1998.© 1998 Wiley‐Liss, Inc.

Posttransplant antidonor lymphocytotoxic antibody production in relation to graft outcome.

Serial serum samples from 266 recipients of primary renal allografts were monitored posttransplant for the presence of panel reactive lymphocytotoxic antibodies (PRA). The minimum posttransplant follow-up period was 18 months. Patients were classified according to whether or not they produced PRA before and/or after transplantation. The groups were as follows: PRA negative before and after transplant, -/-, 171; PRA positive before and negative after transplant, +/-, 5; PRA positive before and positive after transplant, +/+, 27; PRA negative before and positive after transplant, -/+, 63. Actuarial graft survival at 1 year for each group was 81.3%, 100%, 70.4%, 47.6%, respectively. Fifty-five of the 63 -/+ recipients were retrospectively crossmatched with posttransplant sera against stored donor lymphocytes. Of these, 50 (91%) were posttransplant cross match positive, and 37 (67%) have lost their grafts. In 23 of the 26 cases where an anti-HLA specificity was defined, the antibody was directed against antigens present in the donor but not in the recipient. These results clearly indicate that the production of PRA in recipients of renal transplants is associated with antidonor reactivity and poor graft outcome. The fact that these PRA were often directed against donor HLA antigens emphasizes one of the hazards of mismatching for HLA at transplantation.

Importance of minimizing HLA-DR mismatch and cold preservation time in cadaveric renal transplantation.

Univariate and multivariate analyses have been performed on donor an d recipient variables to determine possible effects on the outcome of 516 primary cadaveric renal transplants performed in our single center from 1989 until 1993. The overall actuarial patient survival at 1 year and 5 years was 94.4% and 87.4%, respectively; the 1 year and 5 year graft survival rates were 88.3% and 77.8%, respectively. A total of 95 grafts were lost; death with function (35%) and chronic rejection (22%) were the major causes. Three variables (HLA-DR mismatch, delayed graft function, and prolonged cold ischemia time) had a significant detrimental effect on both short- and long-term graft survival. Zero HLA-DR mismatched grafts showed significantly enhanced survival over those with 1 HLA-DR mismatch both at 1 year (92.8% vs. 84.5%) and at 5 years (88.3% vs. 73.9%) only if cold ischemia time was less than 26 hours (P=0.0009). Occurrence of delayed graft function significantly lowered graft survival at both 1 year and 5 years (P=0.002), and the incidence was significantly associated with prolonged cold ischemia time (P<0.0001). HLA-A or HLA-B matching, percentage panel reactive antibodies (PRA), and anastomosis time showed no independent effect on long-term survival. The small number of 2 HLA-DR mismatched grafts (n=6) precluded separate analysis of this group. Acute rejection accounted for 12% of losses but had no statistically significant effect on graft survival, even though an increased frequency of rejection episodes was significantly associated with HLA-DR mismatch (P<0.0001). These results would suggest that significant survival benefits may be achieved by prospective HLA matching if cold ischemia times are limited. The efficiency of organ sharing must he improved to make optimal use of a limited resource.

Lack of association of HLA polymorphisms with human papillomavirus-related cervical cancer

An association of HLA-DQ3 with SCC of the cervix has been reported by researchers in Germany and Norway. This article documents a similar-sized study with patients and controls from northwest England. We report in detail on serologically determined HLA polymorphism in SCC patients with respect to HPV 16 infection, MHC class II expression within the tumor, serologic response to HPV, and other relevant clinical variables. We have also extended our studies to include DNA-based analysis using PCR and SSO probes for HLA-DQ. No significant association of any HLA-A, -B, -C, -DR, or -DQ antigen with SCC patients was found. While a possible explanation of the differences among studies could be a reflection of disease heterogeneity, the several tumor and clinical factors examined do not account for the observed differences from previous reports. Further studies are needed for a greater understanding of the interaction of HPV and HLA type in the development of cervical neoplasia.

IMMUNOGENETIC FACTORS IN HPV‐ASSOCIATED CERVICAL CANCER: INFLUENCE ON DISEASE PROGRESSION

No HLA allele or specificity was significantly different in frequency between a group of 150 cervical cancer patients from north‐west England and controls (corrected P values). HLA‐DRB 1*1501/DQB 1*0602 was non‐significantly increased, particularly among patients with HPV16‐positive tumours. HLA‐B7‐positive patients had a significantly poorer clinical outcome than HLA‐B7‐negative patients. A significant component of the genotypic effect is down‐regulation of HLA‐B7 expression by the tumour cells.

DETECTION OF HLA-SPECIFIC ANTIBODIES BY PRA-STAT AND THEIR ASSOCIATION WITH TRANSPLANT OUTCOME

OBJECTIVE The aim was to investigate the correlation between renal transplant outcome and the presence of HLA-specific antibodies detected using the ELISA kit PRA-STAT as compared with complement-dependent cytotoxicity (CDC). METHOD 295 sera from 95 renal transplant recipients (99 transplants) were investigated for the presence of HLA-specific antibodies using both PRA-STAT and CDC. The patients were divided into group I (49 transplants failed within 1 month) and group II (50 successful transplants). RESULTS The concordance between PRA-STAT and CDC for the detection of HLA class I-specific antibodies was 87.8% (259 of 295). For 19 sera, antibodies were detected only by PRA-STAT; for 17 sera, antibodies were detected only by CDC. No donor-specific antibodies were detected by either technique for patients in group II. For four group I patients (six sera), donor-specific IgG antibodies were detected only by PRA-STAT (one before, three after transplant) and all four transplants failed. For five other group I patients (six sera), donor HLA-specific antibodies were detected only by CDC (one before, four after transplant) and all five transplants failed. The antibodies detected before transplant by CDC were shown to be IgM alloantibodies. CONCLUSION This study showed that PRA-STAT could detect HLA-specific IgG antibodies relevant to transplant outcome that were not detected by CDC. However, it could not detect IgM alloantibodies that were also shown to be important. PRA-STAT is therefore a useful addition to a histocompatibility laboratorys screening repertoire only when used in conjunction with other techniques.

Rejection in heart transplantation strongly correlates with HLA-DR antigen mismatch

It is well established that incompatible HLA antigens presented by donor tissue readily evoke an immune response. Prospective HLA matching policies, widespread in European kidney transplant centers have reduced the level of HLA mismatching and have significantly improved graft survival. The influence of HLA incompatibility in heart transplantation remains controversial, and prospective HLA matching is seldom achieved. We examined the role of HLA antigen mismatching on transplant rejection by analyzing 2569 endomyocardial biopsies (EMB) from 157 consecutive orthotopic heart transplants performed from April 1987 to August 1993 in our own center. Biopsies were graded according to the accepted International Classification, with grade 2 and higher indicating rejection. Among 91 patients who received a 2 HLA-DR mismatch transplant 34% of 1624 biopsies analyzed were graded as >2. This frequency fell to 29% of 797 biopsies for 53 patients with a one-HLA-DR mismatch and to 18% of 148 biopsies for 13 patients in the zero-HLA-DR-mismatch group (P<0.00005). No significant effect on EMB grade frequencies was observed using the same method of analysis with transplants mismatched at the HLA-A or HLA-B loci apart from analysis of HLA-B matched transplants at 3 months posttransplant (P=0.02). The close linkage of the HLA-B and HLA-DR loci may account for this observation. The results of this study show that heart transplants matched at the HLA-DR locus have a significantly reduced incidence of EMB grades indicative of rejection requiring augmented inununosuppressive therapy. We propose that prospective HLA-DR matching should be adopted for allocation of donor hearts for more efficient use of this precious and limited resource.