Pretransplant serum IgA concentration and IgA-anti-Fab autoantibody activity as prognostic indicators of kidney graft survival

Pre- and Posttransplant IgA Anti-Fab Antibodies to Predict Long-term Kidney Graft Survival

OBJECTIVES

Immunologic factors are reliable markers for allograft monitoring, because of their seminal role in rejection process. One of these factors is the immunoglobulin (Ig)A anti-Fab of the IgG antibody. This study aimed to evaluate the predictive value of pre- and posttransplant levels of this marker for kidney allograft function and survival.

METHODS

Sera samples of 59 living unrelated donor kidney recipients were collected before and after transplantation (days 7, 14, and 30) and investigated for IgA anti-Fab of IgG antibody levels using enzyme-linked immunosorbent assay in relation with allograft outcome.

RESULTS

Among 59 patients, 15 cases (25%) including 10 with acute rejection and 5 with chronic rejection episodes showed graft failure during a mean of 5 years of follow-up. High posttransplant levels of IgA anti-Fab antibodies were observed more frequently in patients with stable graft function (SGF) compared with patients with graft failure (P = 2 × 10(-6)). None of patients with acute or chronic rejection episodes had high levels of IgA anti-Fab antibodies at day 30 posttransplant compared with the SGF group (P = 10(-6) and P = .01, respectively). In addition, high levels of IgA anti-Fab antibody correlated with lesser concentration of serum creatinine at 1 month posttransplantation (P = .01). Five-year graft survival was associated with high levels of pre- and posttransplant IgA anti-Fab antibodies (P = .02 and P = .003, respectively).

CONCLUSIONS

Our findings indicate the protective effect of higher levels of IgA anti-Fab antibodies regarding to kidney allograft outcomes and long-term graft survival.

Early post-transplant immune monitoring can predict long-term kidney graft survival: soluble CD30 levels, anti-HLA antibodies and IgA-anti-Fab autoantibodies

This study aimed to investigate the predictive power of anti-HLA antibodies, sCD30 levels and IgA-anti-Fab autoantibody before and early after transplantation in relation to long-term kidney allograft survival. Pre- and post-transplant sera samples of 59 living-unrelated donor kidney recipients were tested for above risk factors by enzyme-linked immunoabsorbent assay. 15 out of 59 cases experienced rejection episodes (failure group). Pre- and post-transplant high sCD30 levels were significantly associated with graft failure (P=0.02 and P=0.004) and decreased 4 year graft survival (P = 0.009 and P = 0.001). Higher frequency of post-transplant HLA class-II antibody in the absence of class-I antibody was observed in failure group (P=0.007). Patients with post-transplant HLA class-I and class-II antibodies either alone or in combination showed significant lower 4 year graft survival. Recipients with high sCD30 levels in the presence of HLA class-I or class-II antibodies within 2 weeks post-transplant had poor graft survival (P = 0.004 and P = 0.002, respectively). High levels of post-transplant IgA-anti-Fab antibody was more frequent in functioning-graft patients (P = 0.00001), correlated with decreased serum creatinine levels (P = 0.01) and associated with improved graft survival (P = 0.008). Our findings indicate the deleterious effect of early post-transplant HLA antibodies and increased sCD30 levels dependently and protective effect of IgA-anti-Fab antibodies on long-term renal graft outcomes.

Kidney graft recipients with pretransplantation HLA CLASS I antibodies and high soluble CD30 are at high risk for graft loss

In the present study, we investigated whether pretransplantation HLA class I and class II antibodies and pretransplantation levels of soluble CD30 (sCD30) and IgA anti-Fab autoantibodies are predictive of kidney allograft survival. Pretransplantation sera of 504 deceased-donor kidney recipients were tested for IgG HLA class I and class II antibodies, sCD30, and IgA anti-Fab levels using the CTS 4 ELISA kit. Kidney graft survival was estimated by Kaplan-Meier method and multivariate Cox regression. Regardless of the presence of HLA class II antibodies, recipients with high HLA class I reactivity had lower 1-year graft survival than recipients with low reactivity (p < 0.01). Recipients with high sCD30 had lower 5-year graft survival rate than those with low sCD30 (p < 0.01). The sCD30 effect was observed in presensitized and nonsensitized recipients, demonstrated a synergistic effect with HLA class I antibodies (p < 0.001), and appeared to be neutralized in recipients with no HLA class II mismatches. IgA anti-Fab did not influence kidney graft survival. Our results indicate that high pretransplantation sCD30 levels and HLA class I positivity increase the risk of kidney graft loss regardless of other factors. Consequently, such determinations should be routinely performed to estimate recipients' risks of graft rejection before transplantation.

SKEWING OF PRETRANSPLANT ANTI-HLA CLASS I ANTIBODIES OF IMMUNOGLOBULIN G ISOTYPE SOLELY TOWARD IMMUNOGLOBULIN G1 SUBCLASS IS ASSOCIATED WITH POORER RENAL ALLOGRAFT SURVIVAL

Sensitized patients with lymphocytotoxic immunoglobulin (Ig)G anti-human leukocyte antigen (HLA) antibodies have an increased risk of rejection and poorer graft survival. Little is known, however, about the correlation between IgG antibody subclass and clinical outcomes. We identified 20 sensitized renal transplant recipients (panel reactive antibody >15%), all of whom had anti-HLA class I antibodies of an IgG isotype with known specificity before transplantation but who received a crossmatch negative graft. We analyzed the degree of skewing solely toward IgG1 (n=11) or to other IgG subclasses with or without IgG1 (n=9) and correlated these findings with graft survival. At last follow-up (median follow-up 28 months), 6 of 11 patients (55%) with anti-HLA antibodies skewed toward IgG1 had lost their grafts compared with 0 of 9 patients (0%) with anti-HLA antibodies not skewed toward IgG1 (P =0.01 log-rank test). Anti-HLA antibodies of an IgG1 subclass may be a novel marker predicting poor graft outcome.

A large, single center investigation of the immunogenetic factors affecting liver transplantation

BACKGROUND

Reports on the relevance of immunogenetic factors in liver transplantation are often conflicting or inconclusive. We have, therefore, investigated a range of factors that may underlie liver graft survival.

METHODS

The influences of HLA, flow cytometric, and enhanced cytotoxic crossmatching and immunoglobulin (Ig)A levels on graft survival, and acute and chronic rejection were investigated for a single center involving 446 patients over 13 years.

RESULTS

The effect of HLA mismatching on graft survival was significant (P<10(-2)) and was reversed in recipients with autoimmune diseases (P<0.5x10(-2)), whereas the effect of HLA mismatches on the level of acute rejection was detrimental in all recipients. There was a significant effect of a positive cytotoxic crossmatch on 3-month (P<10(-5)) and 1-year (P<10(-4)) graft survival, and an additional effect of the flow cytometric crossmatch was seen for chronic rejection (P<10(-2)) and acute rejection (P<10(-2)). Recipients with HLA-A1,B8,DRB1*0301 had higher levels of acute rejection (P<0.5x10(-2)), and recipients who received an ABO compatible-nonidentical transplant have a significantly higher risk (P<10(-2)) of developing chronic rejection. Finally, the beneficial effect of high serum IgA and, specifically, IgA anti Fab, seen in renal transplants was not evident in liver transplants, and in fact the opposite may be true, at least for acute rejection (P<0.5x10(-2)).

CONCLUSIONS

By separating the recipients with autoimmune disease from other patients and by including acute and chronic rejection as outcome parameters, we have used the power of a large single-centre study to delineate the significance of some of the important immunogenetic factors involved in liver transplantation.

IgA class antibodies and flow cytometric cross-matching in renal transplantation

BACKGROUND

The established method of pretransplant cross-matching does not detect IgA antibodies, and IgA antibodies have thus been ignored when assessing patients for transplantation. The aim of this study was to detect IgA allo- and autoreactive antibodies using flow cytometry and to correlate the results with transplant outcome.

METHODS

Pretransplant sera from 231 sequential renal recipients were tested for serum IgA levels and antibodies directed against the Fab portion of the human IgG molecule. Fifty-nine recipients with sufficient stored donor lymphocytes were also tested by flow cytometry for donor-specific alloantibodies of the IgA isotype.

RESULTS

Graft survival was improved in recipients with higher IgA levels. High IgA anti-Fab levels led to a significantly higher 1-year graft survival (P<0.05). Graft survival was further enhanced where both serum IgA and IgA anti-Fab were raised (P<0.01). Although the mean IgA level tended to be higher for recipients with a positive IgA flow cytometric cross-match (FCXM), the IgA FCXM was not associated with increased IgA anti-Fab, suggesting that the IgA FCXM is detecting a different subset of IgA reactivity. Additionally, for primary grafts, a positive IgA FCXM was not associated with enhanced graft survival.

CONCLUSIONS

Within the repertoire of IgA activity, there are two recognizable groups, the IgA anti-Fab specificity, which is significantly associated with enhanced graft survival, and that detected by the IgA FCXM, which surprisingly is more likely to be positive in less sensitized first grafts and is not associated with enhanced graft survival.

Dynamics of donor-reactive IgG, IgA and IgM antibodies against T and B lymphocytes early after clinical kidney transplantation using flow cytometry

Using flow cytometry, 32 kidney graft recipients were monitored retrospectively for at least 1 month to study the dynamics of serum IgG, IgA and IgM antibodies against donor T and B lymphocytes before and after transplantation. Donor spleen lymphocytes were used as targets. In the B cell cross-match, the surface immunoglobulins were blocked with an anti-human immunoglobulin antibody. A high frequency of donor-reactive antibodies was detected early after transplantation, especially when the sera were tested against B lymphocytes. Surprisingly, donor-reactive antibodies of the IgA isotype made up a substantial proportion of all antibodies detected. Within the first month after transplantation, six out of 32 patients (19%) developed IgG antibodies against donor T lymphocytes and nine out of 35 patients (28%) formed IgG antibodies against B lymphocytes. A similar situation was found for IgA antibodies: 22% of the recipients were positive for IgA antibodies against donor T lymphocytes and 34% against B lymphocytes after transplantation. Lower antibody frequencies were found for IgM antibodies (16% and 19%, respectively). From our data we conclude that for at least some of the parameters studied their individual dynamics reflect the complex immunological mechanisms occurring early after transplantation.