Pitfalls in graft survival analysis

The reliability of a scientific work depends on the accuracy of the analysis. Scientific publications in the field of kidney transplantation still contain methodical errors that may lead to wrong conclusions and result in severe consequences for the patients. Using the data from the Collaborative Transplant Study, we are presenting in this study six examples of the erroneous usage of statistical methods and show how these mistakes can be avoided.

Influence of test technique on sensitization status of patients on the kidney transplant waiting list

The exquisitely sensitive single antigen bead (SAB) technique was shown to detect human leukocyte antigen (HLA) antibodies in sera of healthy male blood donors. Such false reactions can have an impact on critical decisions, especially with respect to the determination of unacceptable HLA-antigen mismatches in patients awaiting a kidney transplant. We tested pretransplant sera of 534 patients on the kidney waiting list using complement-dependent cytotoxicity (CDC), enzyme-linked immunosorbent assay (ELISA) and SAB in parallel. Evidence of HLA antibodies was obtained in 5% of patients using CDC, 14% using ELISA, and 81% using SAB. Among patients without history of an immunizing event, 77% showed evidence of HLA antibodies in SAB. In contrast 98% of these patients were negative in ELISA and CDC. In patients without an immunizing event, SAB-detected antibodies reacted not always weakly but with mean fluorescence intensity (MFI) values as high as 14 440. High-MFI-value antibodies were found in some of these patients with HLA specificities that are rather common in general population, consideration of which would lead to unjustified exclusion of potential kidney donors. False SAB reactions can be unveiled by testing with additional antibody assays. Denial of donor kidneys to recipients based on HLA-antibody specificities detected exclusively in the SAB assay is not advisable.

Algorithms for the determination of unacceptable HLA antigen mismatches in kidney transplant recipients

One of the major tasks of human leukocyte antigen (HLA) laboratories is the pretransplant determination of unacceptable HLA antigen mismatches (UAM) in organ transplant recipients. HLA antigen specificities are determined against which the patient has circulating alloantibodies that are expected to harm the transplanted organ. Using the information on UAM, negative crossmatch (XM) prediction or 'virtual XM' is possible when a potential donor's complete HLA typing is available. Before the introduction of solid-phase antibody detection assays, UAM were determined using the complement-dependent cytotoxicity methodology. After the introduction of the single antigen bead technique, however, various UAM determination algorithms have emerged. In this report, six different laboratories worldwide present how they determine UAM in their collective of kidney transplant recipients in the pretransplant phase and proceed thereafter to transplantation.

Recent developments in desensitization of crossmatch-positive kidney transplant recipients

Currently, there are two major options for the successful and timely transplantation of sensitized kidney transplant recipients: (1) avoidance of the sensitization barrier using special allocation programs, or (2) desensitization. In the case of broadly sensitized kidney patients, a combination of both options might be necessary. This review focuses on new advances in desensitization of crossmatch-positive kidney transplant recipients which include immunoadsorption and the administration of new substances such as the complement C5 inhibitor eculizumab. Finally, integrated algorithms that combine different measures are acknowledged.

Options for immunologic support of renal transplantation through the HLA and immunology laboratories

HLA and immunology laboratories are an integral part of clinical kidney transplant programs. They assist transplant clinicians with evaluating the immunological suitability of potential recipients for transplantation and selecting donor-recipient combinations with a low risk of immunological failure. With sophisticated new techniques becoming available for posttransplant immunological monitoring, laboratories play an increasing supporting role during posttransplant follow up. The level of precision at which immunological testing predicts clinical outcome, however, leaves room for improvement. In this article, we summarize the current state of diagnostics, discuss problems, and point out promising developments.

Post-transplant sCD30 and neopterin as predictors of chronic allograft nephropathy: impact of different immunosuppressive regimens

Immunological monitoring for chronic allograft nephropathy (CAN) is of great potential interest. We assessed serum soluble CD30 (sCD30) together with in vitro Th2-type responses (IL-4, IL-10, CD4 helper activity) and neopterin in a prospective study of 84 renal transplant recipients with 2-year follow-up. Patients were randomized to CsA/Aza, CsA/MMF and Tacr/Aza, respectively, to analyze the effect of immunosuppression on posttransplant sCD30 and neopterin. ATG induction and acute rejections did not alter sCD30 levels whereas CMV disease was associated with transient upregulation of sCD30 (p = 0.003 at 4 months) and sustained upregulation of neopterin (corrected for graft function (Neo/CR) p = 0.005 at 2 years). Tacr versus CsA treatment proved to be an independent variable associated with downregulation of 1-year sCD30, which was positively related to Neo/CR (p = 0.007 and 0.01, respectively; logistic regression). Importantly, increased 1-year sCD30 and Neo/CR were associated with decreased glomerular filtration rate at 2 years (p = 0.02 and p < 0.0005, respectively) and evidence of CAN (p < 0.0005). High 1-year sCD30 could not be attributed to enhanced Th2-type responses and was not associated with HLA antibody formation. Our data suggest that elevated sCD30 and neopterin predict graft deterioration by CAN. Tacr effectively downregulates these responses and might be of advantage in patients with elevated sCD30 or neopterin.

sCD30 and Neopterin as Risk Factors of Chronic Renal Transplant Rejection: Impact of Cyclosporine A, Tacrolimus, and Mycophenolate Mofetil

High pretransplantation sCD30 levels have been shown to be associated with lower 5-year kidney graft survival in mainly Cyclosporine A (CsA)-treated recipients (Collaborative Transplant Study database). To analyze the effect of different immunosupressive regimens (CsA/Azathioprine [Aza], CsA/Mycophenolate Mofetil [MMF], Tacrolimus [Tacr]/Aza) on sCD30, we assessed serum sCD30 and neopterin together with in vitro cytokine responses in a prospective randomized study of 84 renal transplant recipients before, 4 months, and 1 year after transplantation. Panel-reactive antibody (PRA) formation, HLA matching, ATG induction therapy, and acute rejections had no impact on sCD30 levels, whereas cytomegalovirus (CMV) infections induced an up-regulation of sCD30 4 months posttransplantation (P = .003). Whereas MMF showed no effect on sCD30 compared with Aza therapy, we found a significant impact of Tacr versus CsA treatment (1-year sCD30 > or = 60 U/mL: 14/42 (33%), CsA; 1/38 (3%), Tacr; P < .0005). Chronic rejection 2 years posttransplantation was associated with elevated 1-year sCD30 (P = .001) and neopterin levels (P = .006). Our data indicate that the Th2 activation marker sCD30 provides a risk factor for chronic rejection independent of classical immunological risk factors and may be down-regulated using Tacr treatment.

Advances in pre- and posttransplant immunologic testing in kidney transplantation

Pre- and posttransplant risk estimation in kidney transplantation is important for the selection of appropriate treatment strategies. Recently, using new immunologic tests, we made observations within the framework of the Collaborative Transplant Study that may influence clinical practice. Complement-dependent lymphocytotoxic panel reactivity as a measure of anti-HLA sensitization, although criticized for its low sensitivity, is a useful indicator of an increased risk of rejection. Using the more sensitive complement-independent ELISA methodology, which utilizes solubilized HLA molecules instead of lymphocytes, we found that recipients with preformed complement-dependent anti-HLA antibodies showed a decreased graft survival only if their antibodies were directed against both HLA class I and class II, whereas isolated reactivity only against HLA class I or class II was of no clinical consequence. Pretransplant serum-soluble CD30 (sCD30) was found to be an independent and highly predictive factor of immunologic risk. The effects of sCD30 and anti-HLA antibodies were additive. Importantly, even patients without anti-HLA antibodies showed a strong HLA matching effect if their pretransplant serum contained high levels of sCD30. Although the role of anti-HLA antibody formation after transplantation remains uncertain, ELISA-detected sCD30 was shown to indicate impending graft rejection as early as on posttransplant days 3 to 5. Another very sensitive indicator of impending rejection is provided by posttransplant monitoring of the cytotoxic T-lymphocyte effector genes, perforin and granzyme B, in peripheral blood using real-time PCR.

Toxic effects of the herbicide 2,4-dichlorophenoxyacetic acid on lymphoid organs of the rat

We investigated the toxicity of the widely used herbicide dimethylammonium salt of 2,4-dichlorophenoxyacetic acid (DMA-2,4-D) on the lymphoid system of rats after a single dose oral administration using histological, cytochemical and molecular methods. DMA-2,4-D destroyed in a dose- and time-dependent manner the vascular integrity of the thymus and caused cell depletion in the white pulp of the spleen and in the cortex of the thymus, which was at least partly due to programmed cell death. DMA-2,4-D appeared to have hemolytic activity and caused intravascular hemolysis of erythrocytes. An increased hemosiderin content in macrophages of the spleen indicated phagocytosis of lysed erythrocytes. We conclude that acute DMA-2,4-D herbicide poisoning results in severe damage of the lymphatic organs thymus and spleen.

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

IgA concentration and IgA-anti-Fab autoantibody activity were tested in pretransplant sera of 308 kidney graft recipients. Recipients with a serum IgA concentration of 2 g/l or greater had a 1-year graft survival rate of 83%, compared with a 68% rate in recipients with serum IgA of less than 2 g/l (P < 0.005). Serum IgA concentration and IgA-anti-Fab autoantibody activity were significantly associated (r = 0.38, P < 0.0001). Recipients with a high pretransplant IgA-anti-Fab activity had a significantly better graft survival rate (81%) than patients with low pretransplant IgA-anti-Fab (67%, P < 0.025). When IgA-anti-Fab and serum IgA were considered together, 137 recipients with high IgA-anti-Fab and high serum IgA had a 86% 1-year graft survival rate, which was significantly better than the 63% survival rate in patients with low IgA-anti-Fab and low serum IgA (P < 0.0005). The pretransplant serum IgA level and IgA-anti-Fab autoantibody activity were excellent predictors of kidney graft outcome.

Increased soluble Fas in HIV-infected hemophilia patients with CD4+ and CD8+ cell count increases and viral load and immune complex decreases

Previous studies interpreted increases of soluble Fas (sFas) in the plasma during disease progression in HIV-infected patients as evidence of increased apoptosis of CD4(+) lymphocytes. We studied whether sFas and sFas ligand (sFasL) plasma levels are associated with CD4(+) and CD8(+) lymphocyte counts, plasma viral load, and IgM, IgG, C3d, and gp120 complexes on circulating CD4(+) blood lymphocytes in long-term surviving HIV-infected hemophilia patients, most of whom were receiving HAART. Twenty-six hemophilia patients who were infected with HIV in the early 1980s were investigated in 1997, 1998, and 1999. HAART was initiated in 1996 and 1997 in most patients. Lymphocyte subpopulations and immune complex-coated CD4(+) lymphocytes in the blood were investigated by flow cytometry, plasma viral load (HIV-1 mRNA copies/ml plasma) was tested with HIV-1 QT Nuclisens kits, sFas (ng/ml) and sFasL (ng/ml) plasma levels were measured with MBL ELISA kits, and the in vitro response of patient lymphocytes was tested in cell cultures. During the period from 1997 to 1999 we observed an increase in sFas plasma levels (p = 0.003) as well as in CD4(+) (p = 0.004) and CD8(+) (p = 0.023) cell counts; a decrease in IgG (p = 0.047), C3d (p = 0.024), and gp120 (p = 0.001)-coated CD4(+) lymphocytes in the blood; and a decrease in the number of impaired mitogen stimulation assays (p = 0.013). sFas was negatively associated with viral burden (r = -0.662, p = 0.0002) as well as with CD4(+)IgM(+) (r = -0.554, p = 0.004), CD4(+)IgG(+) (r = -0.431, p = 0.031), CD4(+)C3d(+) (r = -0.551, p = 0.041), and CD4(+)gp120(+) (r = -0.430, p = 0.041) blood lymphocytes, CD8(+)DR(+) cell counts (r = -0.700, p = 0.016), and impaired in vitro responses of patient lymphocytes to PHA (r = -0.475, p = 0.016). sFasL was negatively associated with total lymphocyte counts (r = -0.433, p = 0.027), as well as with absolute numbers of CD3(+) (r = -0.492, p = 0.011) and CD8(+) (r = -0.432, p = 0.027) cells. We conclude that, contrary to expectations, sFas plasma levels increased in long-term surviving HIV-infected hemophilia patients receiving HAART, concomitant with increases in CD4(+) and CD8(+) cell counts. Increased sFas may reflect the growing pool of T lymphocytes that recovers because of a decreasing viral burden and a decreasing immune complex load of CD4(+) lymphocytes.

Association of immune complexes and plasma viral load with CD4+ cell depletion, CD8+ DR+ and CD16+ cell counts in HIV+ hemophilia patients. Implications for the immunopathogenesis of HIV-induced CD4+ lymphocyte depletion

OBJECTIVE

There is evidence that HIV induces CD4+ depletion in part by the formation of immune complexes (IC) that attach to CD4+ blood lymphocytes. In the present study we examined the relationship of IC-coated CD4+ blood cells with retroviral replication in HAART-treated patients.

PATIENTS AND METHODS

52 hemophilia patients were studied from 1997 to 1999. Lymphocyte subsets, IgM, IgG and gp120 on CD4+ blood cells, in vitro responses of lymphocytes to mitogens, plasma neopterin and plasma viral load were measured.

RESULTS

Patients with detectable viral replication and without ICs on CD4+ blood lymphocytes had a lower viral load (4100 versus 21000 HIV-1 mRNA copies/ml; P = 0.079) and higher CD4+ cell counts (310/microl versus 161/microl; P = 0.035) than patients with ICs on circulating CD4+ lymphocytes. Among patients with < 80 HIV-1 mRNA copies/ml, IC- individuals had slightly higher CD4+ lymphocyte counts than IC+ patients (384/microl versus 316/microl; n.s.). Further evidence for the clinical relevance of the ICs was obtained when 18 patients who had an undetectable viral load at previous investigations were analyzed. Among patients with a stable undetectable viral load, CD4+ counts increased in 6 of 8 IC- but in none of 2 IC+ individuals. In patients whose viral load increased during the observation period, 5 of 6 IC- but none of 2 IC+ individuals showed higher CD4+ cell counts. Impaired virus killing is suggested by lower CD16+ (35/microl versus 107/microl; P = 0.016), higher CD3+ DR+ (178/microl versus 66/microl; P = 0.006), and higher CD8+ DR+ (142/microl versus 34/microl; P = 0.017) cell counts in IC(-) patients compared to IC- patients without detectable viral load. Strong retroviral replication induced strong T cell dysfunctions. Fewer CD3+ 25+ blood lymphocytes (19/microl versus 47/microl; P = 0.006) and a lower in vitro response of T lymphocytes to the mitogens Con A (RR: 0.3 versus 1.2; P=0.023) and CD3 mab (RR: 0.5 versus 2.4; P = 0.012) was observed in IC+ patients with detectable versus undetectable viral load.

CONCLUSION

Our data suggest that ICs on circulating CD4+ blood lymphocytes are primarily associated with CD4+ lymphocyte depletion whereas the plasma viral load is primarily associated with decreased T lymphocyte activation, lower CD16+ counts, and higher CD8+ DR+ lymphocytes which might be the effector cells for virus elimination.

Induction of apoptosis in human lymphocytes by the herbicide 2,4-dichlorophenoxyacetic acid

Dimethylammonium salt of 2,4-dichlorophenoxyacetic acid (DMA-2,4-D) is a widely used herbicide that is considered moderately toxic. In the present study we found that DMA-2,4-D is able to cause apoptosis in peripheral blood lymphocytes of healthy individuals and Jurkat T cells. Apoptosis induced by DMA-2,4-D was dose and time dependent, independent of Fas, TNF receptor 1 or the aromatic hydrocarbon receptor, and involved disruption of the mitochondrial transmembrane potential and activation of caspase-9. ZVAD-FMK, a broad-spectrum inhibitor of caspases, blocked DMA-2,4-D-induced apoptosis completely. While an inhibitor of caspase-9, as well as caspase-9 and caspase-3 inhibitors in combination, strongly blocked DMA-2,4-D-induced apoptosis, an inhibitor of caspase-3 had a moderate inhibitory effect. Unlike Fas-mediated apoptosis, the initiator caspase, caspase-8, was not involved in DMA-2,4-D-induced apoptosis. Transfection of Jurkat cells with Bcl-2 prevented DMA-2,4-D-induced disruption of the mitochondrial transmembrane potential and led to a complete blockage of apoptosis. Our data indicate that DMA-2,4-D kills human lymphocytes by initiating apoptosis via a direct effect on mitochondria. The activation of caspases occurs downstream of mitochondrial damage, and the dysfunction of mitochondria appears to be sufficient for triggering all downstream events leading to apoptosis.

Graft-protective role of high pretransplantation IgA-anti-Fab autoantibodies: confirmatory evidence obtained in more than 4000 kidney transplants. The Collaborative Transplant Study

BACKGROUND

Preliminary studies showed an excellent success rate of kidney grafts in patients with high pretransplantation serum levels of IgA autoantibodies directed against the Fab region of the human IgG molecule.

METHODS

With the collaboration of 30 centers from around the world, we attempted to verify the role of IgA-anti-Fab autoantibodies in kidney transplantation in an entirely new series of 4316 cadaveric kidney transplants, with special consideration of presensitized and poorly HLA-matched recipients.

RESULTS

In agreement with previously published preliminary findings, 147 recipients with a high pretransplantation IgA-anti-Fab of >1000 had a 2-year kidney graft survival rate of 88+/-3% (+/- SE), compared with an 80+/-1% rate in 851 recipients with a low IgA-anti-Fab of <60 (P = 0.02). Even in patients at an increased risk of graft rejection, high pretransplantation IgA-anti-Fab autoantibody activity was associated with superior graft survival. Among 815 presensitized patients, 31 had a high pretransplantation IgA-anti-Fab activity of >1000 and their 2-year graft survival rate was 94+/-4%, in contrast to a 71+/-4% rate in 165 presensitized recipients with a low IgA-anti-Fab of <60 (P = 0.02). Of 2294 recipients who received a kidney with > or =3 HLA-A+B+DR mismatches, 79 recipients had a high pretransplantation IgA-anti-Fab of >1000 and a 2-year graft survival rate of 90+/-4%, as compared with a 79+/-2% rate in 459 patients with a low IgA-anti-Fab of <60 (P = 0.04).

CONCLUSIONS

The present study confirms that kidney graft recipients with high pretransplantation IgA-anti-Fab activity have excellent graft survival, and it extends this observation to presensitized recipients and poor HLA matches.

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.

Reduction of viral load and immune complex load on CD4+ lymphocytes as a consequence of highly active antiretroviral treatment (HAART) in HIV-infected hemophilia patients

BACKGROUND AND OBJECTIVES

Human immunodeficiency virus (HIV)-induced immune complex load on circulating CD4+ blood lymphocytes is associated with dysfunction and depletion of CD4+ lymphocytes and with increased monocyte/macrophage function. It was investigated whether HAART reduces both the viral load in plasma and the number of immune complex-coated CD4+ lymphocytes in the blood, and whether CD4+ counts are associated with viral load and/or immune complex load.

MATERIALS AND METHODS

Twelve HIV+ hemophilia patients before and after conversion to HAART (group 1); eight HIV+ hemophilia patients without antiretroviral therapy (group 2). HIV-1 RNA copies in plasma using NASBA/Nuclisens kits; CD4+ lymphocytes coated in-vivo with immune complexes using flowcytometry on whole blood samples; in-vitro responses of immune complex-coated T lymphocytes in cell culture assays.

RESULTS

After conversion to HAART there was a significant reduction of viral load, CD4+ gp120+, CD4+ IgM+, and CD4+ IgG+ circulating blood lymphocytes and plasma neopterin, paralleled by a significant increase of CD4+ and CD8+ counts. The percentage of immune complex-coated CD4+ lymphocytes of converted patients was significantly associated with CD4+ counts, in-vitro responses to concanavalin A (Con A), pokeweed mitogen (PWM), phytohaemagglutinin (PHA), anti-CD3 and pooled allogeneic stimulator cells, and with plasma neopterin levels.

CONCLUSION

HAART reduces viral load and HIV-induced immune complex load on circulating CD4+ blood lymphocytes. The results of this study can be interpreted to suggest that HAART increases CD4+ lymphocyte counts in part by counteracting HIV-induced autoimmune phenomena.

Recognition of defined epitopes by affinity-purified anti-immunoglobulin fab autoantibodies isolated from HIV-infected humans

Infection of humans with HIV-1 has previously been independently shown to result in the generation of autoantibodies (AAbs) reactive with immunoglobulin Fab fragments (Heidelberg), and with autoantibodies to T-cell receptors (TCRs) (Tucson). Here, we carry out epitope mapping studies of affinity-purified AAbs to Fab fragments prepared from individual HIV-positive patients for their capacity to bind recombinant constructs and peptide-defined epitopes modeling TCR and Ig light chains. Some affinity-purified autoantibodies reacted strongly with TCRs expressed by intact T-cells, and recombinant Valpha/Vbeta constructs as well as with certain synthetic peptide epitopes. The binding reactions of affinity-purified AAbs of individual patients were distinct, and the AAb preparations consisted of populations of polyclonal lgs as reflected in specificity and isotype. AAb pools from individual patients all bound particular regions of TCR and Ig chains defined by comprehensive peptide synthesis including the CDR1 and Fr3 segments of the variable domains and the joining segment/switch peptide. In addition, other reactivities to restricted regions of alpha, beta and lambda light chains were documented. These results substantiate the cross-reactivity of TCR and Ig-Fab determinants, and are consistent with the hypothesis that autoantibodies arising as a consequence of HIV infection can have an immunomodulatory role.

CD4 depletion in HIV-infected haemophilia patients is associated with rapid clearance of immune complex-coated CD4+ lymphocytes

The predominant immunological finding in HIV+ haemophilia patients is a decrease of CD4+ lymphocytes during progression of the disease. Depletion of CD4+ lymphocytes is paralleled by an increase in the proportion of immune complex-coated CD4+ cells. We examined the hypothesis that the formation of immune complexes on CD4+ lymphocytes is followed by rapid clearance of immune complex-coated CD4+ lymphocytes from the circulation. In this study, the relationship of relative to absolute numbers of immune complex-loaded CD4+ blood lymphocytes and their association with viral load were studied. Two measurements of relative and absolute numbers of gp120-, IgG- and/or IgM-loaded CD4+ lymphocytes were analysed in HIV+ and HIV- haemophilia patients, with a median interval of approx. 3 years. Immune complexes on CD4+ lymphocytes were determined using double-fluorescence flow cytometry and whole blood samples. Viral load was assessed using NASBA and Nuclisens kits. Whereas the proportion of immune complex-coated CD4+ lymphocytes increased with progression of the disease, absolute numbers of immune complex-coated CD4+ lymphocytes in the blood were consistently low. Relative increases of immune complex-coated CD4+ blood lymphocytes were significantly associated with decreases of absolute numbers of circulating CD4+ lymphocytes. The gp120 load on CD4+ blood lymphocytes increased in parallel with the viral load in the blood. These results indicate that immune complex-coated CD4+ lymphocytes are rapidly cleared from the circulation, suggesting that CD4+ reactive autoantibodies and immune complexes are relevant factors in the pathogenesis of AIDS. Relative increases of immune complex-positive cells seem to be a consequence of both an increasing retroviral activity as well as a stronger loading with immune complexes of the reduced number of CD4+ cells remaining during the process of CD4 depletion. The two mechanisms seem to enhance each other and contribute to the progressive CD4 decrease during the course of the disease.

C1q autoantibodies in HIV infection: correlation to elevated levels of autoantibodies against 60-kDa heat-shock proteins

Antibodies to solid phase C1q (C1qAb) were determined in 295 serum samples from 132 HIV-infected subjects and in sera from 140 HIV-seronegative healthy individuals as control. An ELISA method applied for the determination of C1qAb in other diseases was used. In part of these sera, other autoantibodies (antibodies reacting with 60-kDa human heat shock protein (hsp60) or mycobacterial hsp65; IgA and IgG class antibodies against the Fab and F(ab')2 moieties of IgG) as well as complement-mediated antibody-dependent enhancement/neutralization (C'-ADE) were also determined. Increased amount of C1qAb was found in HIV-infected subjects as compared with HIV-seronegative controls (P = 0.0138). In 17 of 132 (13.0%) seropositive individuals but only in 7/140 (5.0%) samples from the controls, the amount of C1qAb exceeded the upper limit (95th percentile) of the normal values (P = 0.031). The amount of C1qAb significantly decreased during a follow-up period of 65 months. C1qAb levels were found to strongly correlate to hsp60/65 autoantibodies but did not correlate or only weakly correlated to the amount of anti-Fab or anti-F(ab')2 autoantibodies measured in the same serum samples. Anti-C1q antibodies recognized the solid phase hsp60/65. Three predicted epitope regions of M. paratuberculosis hsp65 were able to bind efficiently C1q antibodies. An inverse correlation was found between C1qAb and C'-ADE, neutralization was more frequent in the sera with detectable C1qAb, whereas sera without C1qAb more likely enhanced HIV infection in vitro.

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.

Inhibition of HIV-1 rgp120 binding to CD4+ T cells by monoclonal antibodies directed against the gp120 C1 or C4 region

Reagents which block the interaction of HIV-1 gp120 with CD4+ T cell are of therapeutic interest. We assessed the ability of the murine monoclonal antibody (mAb) 87-135/9 to bind to the rgp120 C1 region and to block the CD4 interaction, and compared this with the reactivity of the rat mAb 388/389 or the human mAbs F105 and b12, which are known to bind within or near the gp120 C4 region. ELISA and surface plasmon resonance measurements showed that mAb 87-135/9 recognized specifically the gp120 C1 peptide HEDIISLWDQSLK (residues 105-117). All four mAbs bound to rgp120 and blocked its interaction with CD4+ T cells. When mAb 87-135/9 was used in combination with one of the other antibodies, its inhibitory effect was additive. A therapeutic approach could be to use a human anti-gp120/CD4bs conformational mAb in combination with a humanized Ab directed against the conserved, linear gp120 C1 epitope and/or an anti-viral drug to hinder the HIV-1 virus and shedded envelope protein to bind to CD4+ T cells.

Activated autologous blood therapy in recurrent spontaneous abortion--results of a pilot study

This study was undertaken to investigate the influence of activated autologous blood therapy on immunological parameters and on the clinical outcome in patients with recurrent spontaneous abortion. In a prospective trial, 36 women with recurrent spontaneous abortion were treated with intramuscular reinjections of extracorporally haemolysed and ultraviolet irradiated autologous blood. A comprehensive immunological investigation revealed significant changes in lymphocyte subpopulations, plasma complement levels, mitogen stimulation and immunoglobulin levels during the treatment period. No side-effects were reported by the patients. From June 1994 to November 1995, 22 intrauterine and one extrauterine pregnancies occurred, resulting in 19 (86%) live births, two (9%) spontaneous abortions and one (4%) artificial abortion compared with a 64% live birth rate in the historical control group. We conclude that activated autologous blood therapy has detectable effects on the immune system, and seems to be promising for further investigation concerning the treatment of idiopathic recurrent spontaneous abortion.

Association of viral load in plasma samples of HIV-infected hemophilia patients with autoantibodies and gp120-containing immune complexes on CD4+ lymphocytes

OBJECTIVE

We investigated whether the induction of antilymphocyte autoantibodies and immune complexes is associated with the activity of HIV replication.

METHODS

Viral HIV-1 RNA was measured in the plasma samples of 84 HIV+ hemophilia patients and correlated with the IgM, IgG, IgM/IgG and IgM/IgG/gp120 load of circulating CD4+ lymphocytes, CD4+ and CD8+ cell counts, plasma neopterin levels and in vitro T-cell responses to mitogens and pooled allogeneic stimulator cells.

RESULTS

Compared to patients with no immune complexes, on circulating CD4+ lymphocytes, viral load was increased in patients with IgM, IgM/IgG or IgM/IgG/gp120 complexes. Sequential analysis of HIV+ patients showed that peaks of retroviral activity were associated with the subsequent formation of CD4+ lymphocyte-reactive IgM and IgG autoantibodies and gp120-containing immune complexes.

CONCLUSION

The induction of autoantibodies and immune complexes attached to CD4+ lymphocytes is associated with periods of increased viral activity in HIV-infected patients.

Relationship between progression of disease and immunoglobulin A-anti-Fab-/F(ab')2 autoantibodies in patients with head and neck cancer

Patients with malignant tumors of the head and neck often have immune defects. Higher serum immunoglobulin (Ig)A levels were reported in this group of patients. We investigated whether IgA-anti-Fab- or IgA-anti-F(ab')2 autoantibodies, which have been shown to correlate with severe dysfunction of the immune system, also appear in patients with head and neck cancer. Sera of 110 patients with squamous cell carcinoma (SCCHN), eight patients with adenoid cystic carcinoma, and 57 healthy control subjects were tested by enzyme-linked immunosorbent assay for IgA-anti-Fab autoantibody activity. Patients with head and neck cancer showed a higher IgA-anti-Fab activity (optical density (OD) = 399; n = 118) than did healthy control subjects (OD = 84; n = 57; p < 0.0001). An association between stage of disease and IgA-anti-Fab activity could be established in patients with SCCHN. Patients with stage IV disease had a significantly higher IgA-anti-Fab activity (OD = 538; n = 51) than had patients with stage I disease (OD = 283; n = 18; p < 0.05). Patients with stage II (OD = 293; n = 13) or stage III (OD = 379; n = 28) disease had intermediate activity. Also a higher IgA-anti-Fab activity than in healthy control subjects could be shown in the eight patients with adenoid cystic carcinoma (OD = 314; n = 8; p < 0.01). The highest IgA-anti-Fab activity was observed in eight patients with SCCHN who died within 6 months after testing (OD = 1004; n = 8), suggesting an association between autoimmunity and final desintegration of physiologic body functions. The occurrence of IgA-anti-Fab/IgA-anti-F(ab')2 autoantibodies might be interpreted as an aspect of immune deficiency in patients with malignant tumors of the head and neck.

Anti-MIP-1alpha and anti-RANTES antibodies: new allies of HIV-1?

The human immunodeficiency virus type 1 was recently found to use several chemokine receptors in addition to the CD4 molecule for attachment to, and fusion with, CD4+ cells. The interaction between macrophage-tropic HIV-1 strains and one of these chemokine receptors, CCR5, was shown to involve the V3-loop of the viral envelope glycoprotein gp120. Physiological ligands of CCR5, namely the beta-chemokines MIP-1alpha, MIP-1beta, and RANTES, were found to competitively inhibit the V3-loop-CCR5 interaction. We therefore hypothesized that the V3-loop of gp120 of macrophage-tropic HIV-1 may share a binding site on CCR5 with MIP-1alpha, MIP-1beta, and RANTES and that the V3-loop therefore might have some homology with these beta-chemokines. In the present study, we could demonstrate that affinity purified anti-V3-loop antibodies isolated from serum of an HIV-1-infected patient bound to MIP-1alpha and RANTES. Furthermore, sera of HIV-infected hemophilia patients without AIDS or ARC had significantly higher anti-MIP-1alpha and anti-RANTES antibody activities than sera of HIV-infected hemophilia patients with AIDS. We speculate that the higher activities of anti-MIP-1alpha and anti-RANTES antibodies in asymptomatic HIV-1 infected individuals might be due to a cross-reaction of beta-chemokines with anti-V3-loop antibodies raised against gp120 of macrophage-tropic HIV-1 strains, known to be prevailing in the asymptomatic stage of HIV infection. Such anti-chemokine antibodies may play a deleterious role in the pathogenesis of AIDS by reducing the chemokines' potential to inhibit HIV-1 entry into CD4+ cells.

[Illness stage and IgA-anti-Fab/F(ab')2 autoantibody activity in serum of patients with malignant head-neck tumors]

BACKGROUND

Patients with malignant tumors of the head and neck often show immune defects. Increased serum IgA levels have been reported in these groups of patients. We investigated whether IgA-anti-Fab or IgA-anti-F(ab')2 autoantibodies, which have been shown to correlate with severe dysfunction of the immune system, also appear in patients with head and neck cancer.

PATIENTS

Sera of 110 patients with squamous cell carcinoma, eight patients with adenoid cystic carcinoma, and 57 healthy controls were tested with an ELISA for IgA-anti-Fab autoantibody activity.

RESULTS

Patients with head and neck cancer showed a higher IgA-anti-Fab activity (OD:399, n = 118) than healthy controls (OD: 84, n = 57, p < 0.0001). An association between stage of disease and IgA-anti-Fab activity could be established in patients with SCCHN. Stage IV patients had a significantly higher IgA-anti-Fab activity (OD: 538, n = 51) than stage 1 patients (OD: 283, n = 18, p < 0.05). Patients with stage II (OD: 293, n = 13) or stage III (OD: 379, n = 28) showed intermediate activity. Also a higher IgA-anti-Fab activity than in healthy controls was demonstrated in the eight patients with ACCHN (OD: 314, n = 8, p < 0.01). The highest IgA-anti-Fab activity was observed in eight patients with SCCHN who died within six months after testing (OD: 1004, n = 8). Similar results were obtained for IgA-anti-F(ab')2 autoantibodies. Our findings suggest an association between autoimmunity and final desintegration of physiological body functions.

CONCLUSIONS

The occurrence of IgA-anti-Fab/IgA-anti-F(ab')2 autoantibodies might be interpreted as an aspect of immune deficiency in patients with malignant tumors of the head and neck.

Association of T cell dysfunction with the presence of IgG autoantibodies on CD4+ lymphocytes in haemophilia patients; results of a 10-year study

HIV induces progressive dysfunction followed by numerical depletion of CD4+ lymphocytes. IgG autoantibodies and gp 120-containing immune complexes have been implicated in the pathogenesis of AIDS. We carried out a longitudinal study in 19 HIV- and 72 HIV+ haemophilia patients over a 10-year period in order to investigate a possible relationship between the occurrence of autoantibodies and CD4+ lymphocyte changes. IgM, IgG, C3d and gp120 on the surface of CD4+ lymphocytes were determined in heparinized whole blood with flow cytometry and double-fluorescence. The in vitro response of autoantibody-coated cells was tested in cell cultures with concanavalin A (Con A), phytohaemagglutinin (PHA), pokeweed mitogen (PWM) anti-CD3 MoAb or pooled allogeneic stimulator cells (MLC). After a 10-year follow up, 12 of 71 HIV+ and 16 of 19 HIV- haemophilia patients showed no evidence of immunoglobulins on circulating CD4+ lymphocytes. HIV- haemophilia patients without autoantibodies had CD4+ and CD8+ cell counts in the normal range (957+/-642/microliters and 636+/-405/microliters) and normal T cell responses in vitro (mean relative response (RR) > or = 0.7). In contrast, HIV+ haemophilia patients showed immunological abnormalities which were associated with the autoantibody and immune complex load of CD4+ blood lymphocytes. HIV+ patients without autoantibodies had a mean CD4+ lymphocyte count of 372+/-274/microliter, a mean CD8+ lymphocyte count of 737+/-435 microliter, and normal T lymphocyte stimulation in vitro (mean RR > or = 0.7). HIV+ patients with complement-fixing IgM on CD4+ lymphocytes had somewhat lower CD4+ (255+/-246/microliters, P = NS) and CD8+ (706 +/- 468/microliters, P = NS) lymphocyte numbers, and also normal T lymphocyte stimulation (mean RR > or = 0.7) in vitro. However, patients with complement-fixing IgG autoantibodies showed a strong decrease of CD4+ (150 +/- 146/microliters, P< 0.02) and CD8+ (360 +/- 300 microliters, (P<0.02) lymphocytes and impaired CD4+ lymphocyte stimulation in vitro with a mean RR of 0.5+/-0.5 for Con A (P = NS), 0.7 +/- 0.8 for PHA (P<0.03), 0.4 +/- 0.4 for PWM (P = NS), 0.8 +/- 1.2 for anti-CD3 MoAb (P<0.04) and 0.7 +/- 1.0 for pooled allogeneic stimulator cells (P=0.05). Patients with gp120-containing immune complexes on CD4+ blood lymphocytes demonstrated strongly decreased CD4+ (25+/-35/microliters, P<0.0001) and CD8+ (213+/-212/microliters, P<0.006) lymphocyte counts as well as strongly impaired T lymphocyte responses in vitro upon stimulation with PHA (RR 0.2+/-0.1, P<0.02), PWM (RR 0.2+/_0.2, P=0.05), anti-CD3 MoAb(RR 0.1+/-0.1, P<0.04), and allogeneic stimulator cells (RR 0.2+/-0.1, P<0.02). These data led us to speculate that autoantibody formation against CD4+ lymphocytes is an important mechanism in the pathogenesis of AIDS. We hypothesize that autoantibodies against circulating CD4+ lymphocytes inhibit CD4+ cell function, especially the release of cytokines, and induce CD4+ cell depletion. The reduction and dysfunction of CD4+ lymphocytes may be responsible for the CD8+ cell depletion observed in HIV+ patients.

Identification of complement activation sites in human immunodeficiency virus type-1 glycoprotein gp120

Recombinant glycoprotein 120 (rgp120) of human immunodeficiency virus type-1 (HIV-1) activates the human complement system in the absence of anti-gp120 antibodies. HIV-1 glycoprotein gp120 can dissociate from the viral envelope either spontaneously or after binding of HIV-1 to the CD4 molecule. As a consequence, gp120 can circulate in the patient's serum and attach to the surface of uninfected CD4+ T cells. Complement activation by cell-bound HIV-1 glycoprotein gp120 with subsequent opsonization may represent a mechanism for the elimination of uninfected CD4+ cells by the reticuloendothelial system, thereby enhancing the progression of HIV disease. In the current study, the complement proteins C4,C3,C5,C9, and properdin were found to bind to a synthetic peptide covering positions 233-251 of the gp120BRU sequence on incubation with normal human serum. Complement activation by the peptide was comparable with that induced by aggregated IgG, complete rgp120, and the previously described complement-activating gp41-peptide 609-623. Activation occurred via the classical pathway and was abrogated in the presence of EDTA, Mg2+/EGTA, or C4-deficient human serum. Peptides partly overlapping the sequence 233-251 activated complement to a lesser extent. The complement-activating capacity of the gp120 sequence 233-251 was not restricted to the HIV-1BRU isolate, because a peptide from the corresponding sequence of the HIV-1MN strain was also capable of activating complement. An additional strong complement-activating site was identified in the gp120 sequence 321-360 of the HIV-1MN strain. These data indicate that distinct sites in gp120 are able to activate human serum complement via the classical pathway in the absence of anti-gp120 and independent of glycosylation.

CD8+ lymphocyte decrease in HIV disease: association with anti-CD4+ but not with anti-CD8+ lymphocyte autoantibodies

HIV+ patients form autoantibodies against CD4+ and CD8+ lymphocytes. It was shown that anti-CD4+ lymphocyte autoantibodies are associated with the depletion of CD4+ cells. In the present study we analyzed the relationship of anti-CD4+ and anti-CD8+ autoantibodies with the CD8+ lymphocyte decrease commonly observed during HIV disease. IgM and IgG antibodies as well as complement fragments were determined on the surface of CD4+ and CD8+ lymphocytes using double fluorescence flow cytometry. Anti-CD8+ lymphocyte autoantibodies were found more often in HIV + hemophilia patients (75/105 = 71%) than HIV- hemophilia patients (13/37 = 35%; p < 0.0001), patients with pharyngeal carcinoma (20/44 = 45%; P = 0.002), habitual abortions (3/13 = 23%; p = 0.0009) or healthy individuals (93-223 = 42%; p < 0.0001). Anti-CD8+ antibodies, mostly of the IgM type, occurred significantly more frequently than anti-CD4+ antibodies in healthy controls (p < 0.0001), patients with pharyngeal carcinoma (p = 0.0001), or HIV- patients (p = 0.01). In HIV+ patients, however, anti-CD4+ autoantibodies were found more often than anti-CD8+ antibodies (85 vs 71%; p = 0.02). 70 of 104 (67%) HIV+ patients had autoantibodies on both CD4+ and CD8+ lymphocytes and the IgG/IgM/C3d autoantibody pattern was identical in 31 (44%) of the patients. Interestingly, peripheral blood CD8+ cell counts were significantly associated with anti-CD4+ (p = 0.01) but not with anti-CD8+ lymphocyte autoantibodies. It is hypothesized that the inhibition and depletion of CD4+ cells by anti-CD4+ autoantibodies is associated with a loss of regulatory functions that leads to a depletion of antiviral cytotoxic CD8+ lymphocytes.

Sequential occurrence of IgM, IgM/IgG, and gp120-IgM/IgG complement complexes on CD4+ lymphocytes in relation to CD4+ blood lymphocyte depletion in HIV+ hemophilia patients: results of a 10-year study

The concept of autoimmune mechanisms playing an integral role in the pathogenesis of HIV disease is rapidly gaining ground. In this study, we determined IgM and IgG antibodies, complement fragments and gp120 on the surface of CD4+ lymphocytes using double-fluorescence flow cytometry. Sequential analysis demonstrated an inverse relationship of autoantibodies and CD4+ lymphocyte counts in the peripheral blood. HIV+ patients without autoantibodies (16/104 = 15%) had the highest CD4+ blood cell counts (324 +/- 264/microliters; mean +/- SD). CD4+ counts were successively lower in patients with complement-fixing IgM (243 +/- 240/microliter), complement-fixing IgG and IgM (139 +/- 138/microliter), or gp120-IgM/IgG complement complexes on the surface of CD4+ cells (38 +/- 45/microliter, P = 0.03). Individual patient profiles show that IgM autoantibodies typically are formed early after HIV infection and appear to deplete CD4+ lymphocytes very slowly, whereas complement-fixing IgG autoantibodies are generated at a later stage and deplete CD4+ lymphocytes more efficiently. The presence of both soluble gp120 and complement-fixing autoantibodies on CD4+ lymphocytes is associated with very low CD4+ cell counts and coincides with progression to terminal disease. Early during HIV infection autoantibody production is rather unstable, but it becomes more stable with disease progression and persists in advanced stages of the disease. These data suggest that autoantibody formation against CD4+ lymphocytes is a pathogenic mechanism for CD4+ cell depletion.

Interaction of complement and specific antibodies with the external glycoprotein 120 of HIV-1

Previously we have investigated the interaction of human complement as well as one polyclonal and three human monoclonal antibody preparations with the human immunodeficiency virus type-1 (HIV-1) transmembrane recombinant glycoprotein (rgp41). A strong competition was found between the antibodies and deposited complement proteins for the same binding sites located within the immunodominant region of rgp41. The aim of the present experiments was to see if the same type of antibody-complement-HIV-1 interactions could be observed with the outer envelope glycoprotein (rgp120) of HIV-1. Three different glycosylated rgp120 preparations, as well as a synthetic peptide corresponding to the V3 loop of the MN strain, were adsorbed to enzyme-linked immunosorbent assay (ELISA) plates and incubated with mixtures of anti-rgp120 antibodies and normal human serum (NHS) as a complement source. Fixed complement proteins and antibodies were detected with specific, peroxidase-labelled antibodies against different complement proteins (C1q, C4b, C3b) and the gamma-chain of antibodies. In the absence of anti-rgp120, high amounts of C3 were deposited to each rgp120 preparation tested (including the V3 peptide) but significant differences in the amounts of bound C1q and C4b were observed. Using sera deficient in different complement proteins, we found that both the classical and the alternative pathways contributed to the C3 binding to rgp120. Addition of specific antibodies did not increase complement activation by rgp120 and only in the case of a monoclonal antibody to the V3-loop could we see complement-dependent inhibition of antibody binding.

Complement activation by recombinant HIV-1 glycoprotein gp120

The mechanism of CD4+ cell depletion in HIV-infected patients is poorly understood. In this study we investigated whether rgp120 can activate the complement system in the absence of anti-gp120 Abs. We found that the complement proteins C4, C3d, C5b-9, and properdin bind to rgp 120-coated CD4+ T cells of healthy individuals when incubated in autologous serum. Activation of the complement system occurred primarily via the classical pathway and was abolished in sera deficient in C1q and C4 as well as in the presence of EDTA. No cell lysis was observed in a lymphocytotoxicity assay using human serum, possibly because of homologous restriction of complement lysis. In contrast, addition of rabbit sera induced lysis of the rgp 120-precoated cells. Cell lysis by rabbit serum was found to be because of naturally occurring IgM anti-gp 120 Abs. The rgp 120, which was immobilized on the surface of microtiter plates activated complement in the absence of lymphocytes. Complement activation by cell-bound HIV-1 envelope glycoprotein gp120 with subsequent opsonization may be relevant for the elimination of noninfected CD4+ T cells in HIV-infected patients.

Complement activation by recombinant HIV-1 glycoprotein gp120

The mechanism of CD4+ cell depletion in HIV-infected patients is poorly understood. In this study we investigated whether rgp120 can activate the complement system in the absence of anti-gp120 Abs. We found that the complement proteins C4, C3d, C5b-9, and properdin bind to rgp 120-coated CD4+ T cells of healthy individuals when incubated in autologous serum. Activation of the complement system occurred primarily via the classical pathway and was abolished in sera deficient in C1q and C4 as well as in the presence of EDTA. No cell lysis was observed in a lymphocytotoxicity assay using human serum, possibly because of homologous restriction of complement lysis. In contrast, addition of rabbit sera induced lysis of the rgp 120-precoated cells. Cell lysis by rabbit serum was found to be because of naturally occurring IgM anti-gp 120 Abs. The rgp 120, which was immobilized on the surface of microtiter plates activated complement in the absence of lymphocytes. Complement activation by cell-bound HIV-1 envelope glycoprotein gp120 with subsequent opsonization may be relevant for the elimination of noninfected CD4+ T cells in HIV-infected patients.

Comparative study of antibodies that are associated with disease progression in HIV disease

Two types of antibodies which previously were found to be inversely associated with CD4+ cell counts and which may contribute to the progression of HIV disease were measured in parallel in 55 serum samples of 7 longitudinally tested HIV-infected patients (4 homosexual men, 3 haemophilic men) and in 15 serum samples from 15 patients with advanced AIDS. HIV-infection enhancing antibodies were determined in the presence of near-physiologic human complement concentration using a complement receptor type 2 (CR2) carrying HIV-target cell line. IgG and IgA class autoantibodies directed against human IgG-Fab fragments were measured in specific ELISA assays. In agreement with our previous studies obtained in HIV-seropositive haemophilic patients, significant negative correlations were found between CD4+ cell counts and IgG anti-Fab and IgA anti-Fab antibodies (Spearman correlation coefficient r = -0.587, P < 0.0001; and r = -0.269, P = 0.024, respectively). A significant positive correlation was observed between complement-dependent enhancing antibodies and IgA anti-Fab antibodies (r = 0.408, P = 0.003), whereas the correlation with IgG anti-Fab antibodies was only weak (r = 0.288, P = 0.034). Serum samples with high titres of complement-dependent enhancing antibodies had almost 3 times higher IgA anti-Fab autoantibody activity than sera with low titres (P = 0.0038). Our findings indicate that the two disease markers in HIV disease, enhancing antibodies and autoantibodies directed against the Fab moiety of IgG, are not identical. However, anti-Fab antibodies may contribute to complement-dependent HIV infection enhancement.

Association of IgA-anti-Fab autoantibodies with disease stage in head-and-neck cancer

Patients with head-and-neck cancer commonly have immune defects. It was reported that these patients have raised serum IgA levels. We investigated whether IgA-anti-Fab autoantibodies, which occur in association with immune dysfunction, are present in patients with head-and-neck cancer. Sera of 101 patients with squamous-cell carcinoma (SCCHN) and 8 patients with adenoid cystic carcinoma (ACCHN) of the head and neck were tested in ELISA for IgA-anti-Fab autoantibody activity. IgA-anti-Fab serum activity was significantly higher in both SCCHN and ACCHN patients than in healthy controls. In patients with SCCHN, an association between disease stage and IgA-anti-Fab activity was established. Stage-IV patients had significantly higher IgA-anti-Fab than stage-I patients or healthy controls. Stage-II and stage-III patients had intermediate levels. Extremely high IgA-anti-Fab activity was observed in 7 patients who died within 6 months following testing, suggesting a relationship of autoimmunity with terminal disintegration of physiological body functions. IgA-anti-Fab autoantibodies may explain the occurrence of immune defects in patients with head-and-neck cancer.