AB0351 IMPACT OF FCGR2A, FCGR3A AND FCGR3B POLYMORPHISM ON RITUXIMAB EFFICACY IN RHEUMATOID ARTHRITIS

Background

Identifying reliable biomarkers of response to biologics in rheumatoid arthritis (RA) is necessary to improve responsiveness, preserve functions and structure of joints, as well as to reduce treatment’s cost. Single nucleotide polymorphisms (SNP’s) of Fc-gamma receptors genes (FCGRs), by inducing a variation of receptors’ affinity to Fc fragment of Gamma immunoglobulin, might influence the efficacy of therapeutic monoclonal antibodies by modifying their clearance.

Objectives

The aim of this study was to investigate whether FCGR2A, FCGR3A and FCGR3B SNP’s were predictive factors of response to rituximab (RTX) in Tunisian RA patients.

Methods

A cross-sectional, observational and analytic multicentric cohort study was conducted in a group of patients suffering from RA treated with RTX. Treatment outcome was evaluated after 6 months, using DAS28 variation from baseline and EULAR response criteria. R131H-FCGR2A, F158V-FCGR3A and NA1/NA2-FCGR3B SNPs were studied using PCR-SSP and direct sequencing process.

Results

Thirty-four patients were enrolled with a sexe ratio M/F=5/29. The mean age at inclusion was 54,24±11,78 years [29-77]. All patients received at least one cs-DMARDS priorly to the prescription of RTX. Concomitant treatment with methotrexate was pursued in 77,3% of patients. As shown in Table 1, an association, that tend to signification, was found between R/R FCGR2A receptors and a greater variation in DAS28 score (p=0,053). This association was also found using EULAR criteria, since all patients with R/R genotypes had a good or moderate response to RTX but was not significative (p=0,131).

Table 1.

Correlation of FCGR SNPs with response to rituximab at 6 months of treatment

Genetic studyΔDAS28CRPpΔDAS28ESRpEULAR (R-) (n=7)EULAR (R+) (n=27)PFCGR2A R131H*0,1380,7610,301GenotypesRR2,53±1,560,0531,83±0,750,4800(0)7 (100)0,131HH2,05±2,510,8682,29±1,640,6831 (33,3)2 (66,7)0,576RH1,09±1,360,062,00±1,730,8556 (25)18(75)0,324AllelesR1,45±1,520,8681,96±1,490,6836 (0,194)25(0,806)0,576H1,17±1,430,0532,1±1,600,4807 (0,259)20(0,741)0,131FCGR3A F158V*0,4280,8730,370GenotypesFF1,35±1,570,8601,91±1,860,7052 (16,7)10(83,3)0,676VV0,95±0,980,2882,85±0,320,6371 (10)9(90)0,324FV2,06±1,830,2371,84±1,5114 (33,3)8(66,7)0,175AllelesF1,72±1,700,2881,87±1,560,6376 (0,25)18(0,75)0,324V1,56±1,570,8602,13±1,330,7055(0,227)17(0,773)0,676FCGR3B NA1/NA2*0,2170,4850,645GenotypesNA1NA12,29±1,810,092,13±1,080,7152(22,2)7 (78,8)0,888NA2NA20,79±1,300,3290,60,3432 (33,3)4 (66,7)0,395NA1NA21,23±1,360,3912,28±2,070,3453 (15,8)16(84,2)0,436AllelesNA21,15±1,330,091,95±1,950,7155 (0,20)20(0,80)0,888NA11,60±1,580,3292,19±1,450,3435 (0,179)23(0,821)0,395

DAS: disease activity score,ΔDAS: mean variation of DAS at 6 months, *:Comparison of the global distribution of the 3 genotypes,**: p while comparing the prevalence of R/R genotype to R/H and H/H genotypes,R+: good or moderate EULAR response,R-: bad EULAR response

Conclusion

The low affinity receptor R/R FcgRIIa might be predictive of good response in RA patients treated with RTX. More studies need to be conducted in larger cohorts to confirm this association, with the aim of identifying reliable biomarkers of response to biologics to improve responsiveness, preserve joints functions and structure, as well as reduce treatment’s cost.

Disclosure of Interests

None declared

AB0307 DOES FCGR2A, FCGR3A AND FCGR3B POLYMORPHISM CAN PREDICT ANTI-DRUG ANTIBODIES APPARITION IN RHEUMATOID ARTHRITIS PATIENTS TREATED WITH TNF-BLOCKERS?

Background:

Fc gamma receptors (FcγRs) play a major role in the regulation of humoral immune responses. Single-nucleotide polymorphisms (SNPs) of FCGR2A and FCGR3A and FCGR3B can impact the expression level, IgG affinity and function of the CD32 and CD16 FcγRs in response to their engagement by the Fc fragment of IgG. It was described in patient treated for rheumatoid arthritis (RA), that such a polymorphism may influence patients response to TNF-blockers.

Objectives:

In this study, we aimed to investigate whether the FCGR2A H131R (rs1801274), FCGR3A F158V (rs396991), and FCGR3B NA1/NA2 polymorphisms can be involved in the genesis of anti-drug-antibody ADAb to anti-TNF therapy in RA patients under etanercept (ETA), adalimumab (ADL) and infliximab (INF).

Methods:

We included 47 patients treated for RA under TNF-blockers. To assess the association between the FCGR2A H131R (rs1801274), FCGR3A F158V (rs396991), and FCGR3B NA1/NA2 polymorphisms and immunogenicity of TNF-blockers, we used allele contrast, the recessive model, the dominant model, and the homozygote contrast. Quantitative measurements of the ADAbs was carried out by a commercial enzyme-linked immunosorbent assay (ELISA) kit (Promonitor)®after 6 months of treatment.

Results:

We involved 18 patients treated with ETA, 13 patients with ADL and 16 under INF. None of the patients under ETA has developed ADAb and respectively 1 and 7 patients developed immunogenicity with ADL and INF. We excluded patients under ETA from statistical study since they didn’t develop ADAb.

A significant association was revealed between FCGR2A H131R polymorphism and immunogenicity of INF and ADL (table 1).

Table 1.

Association between FCGR2A polymorphism and immunogenicity to INF and ADL

FCGR2A association with ADAb (n=29, crude analysis)GenotypeADAb=0ADAb=1OR (95% CI)P-valueH/H1 (4.8%)3 (37.5%)1.000.031H/R-R/R20 (95.2%)5 (62.5%)0.08 (0.01-0.98)

There weren’t significant associations between ADAb’s development and FCGR3A F158V and FCGR3B NA1/NA2 polymorphism.

Conclusion:

FCGR2A R allele carriers show less susceptibility to develop ADAb to ADL and INF with follow-up times of 6 months. Our results provide an explanation for controversies in the relationships between FCGR2A H131R polymorphism and TNF-blockers response. Further studies with larger population of RA patients should be undertaken to confirm this hypothesis.

References:

None

Disclosure of Interests:

None declared

The evaluation of the relevance of thrombin generation and procoagulant activity in thrombotic risk assessment in BCR-ABL-negative myeloproliferative neoplasm patients

INTRODUCTION

It has been recently suggested that microparticles (MP) play a role in the pathogenesis of thrombotic complications. This study aimed to assess the contribution of procoagulant activity expressed by circulating MP in thrombotic events in MPN patients.

METHODS

Seventy-four MPN patients were enrolled in a trans-sectional study. The MP procoagulant activity was measured using two assays: (i) the thrombin generation (TG) assay used in different conditions with the addition of both tissue factor (TF) and phospholipids (PL) and with the addition of TF or PL alone and (ii) the PROCOAG-PPL assay.

RESULTS

The mean age was 62 (26 men and 48 women). The prevalence of thrombotic events was 28%. When comparing patients with thrombosis to those without, age, sex, MPN type, cardiovascular risk factors, and history of thrombosis were not significantly associated with thrombosis. The JAK2 V617F mutation was significantly associated with thrombotic events (90% vs 67%; P=.04). Results from the TG assay and the PROCOAG-PPL assays did not demonstrate a significant association between the MP procoagulant activity and thrombotic events.

CONCLUSION

The MP procoagulant activity did not predict thrombosis in MPN patients. The contribution of TG assay in the assessment of the thrombotic risk is still in debate.

Effect of Risk Alleles in CFH, C3, and VEGFA on the Response to Intravitreal Bevacizumab in Tunisian Patients with Neovascular Age-related Macular Degeneration

Purpose. The aim of this pharmacogenetic study was to evaluate the impact of high-risk alleles in factor H, factor C3 and vascular endothelial growth factor (VEGF) on the response to intravitreal bevacizumab in patients with neovascular age-related macular degeneration (AMD) in a Tunisian population. Methods. Ninety patients with active neovascular AMD treated with intravitreal bevacizumab injections were enrolled in the study. Treatment response was evaluated by comparing BCVA at baseline and at 12 months. Patients were classified into either "poor responders" (PR) or "good responders" (GR). Single nucleotide polymorphism (SNP) genotyping was performed for rs1061170 in FH, rs2230199 in C3 andrs699947, rs2010963 and rs3025039 in VEGF. The association between genotype and visual response at 12 months was assessed. Results. Seventy-seven participants were assigned to the GR group and 13 to the PR group. No correlation was found between FH, C3 and VEGF variant alleles and treatment response. However, haplotype analysis of rs699947 ((- 2578) C/A), rs2010963 ((+ 405) C/G) and rs3025039 ((+ 936) C/T) SNPs revealed that the AGT haplotype was associated with a poor response at 12months (p = 0.048). No association was found between treatment response and the cumulative effect of all high-risk alleles of C3, FH and VEGF. All three types of CNV were found in both groups at a comparable frequency. Conclusions. The VEGF haplotype TGA could be used as a marker for poor visual prognosis in Tunisian patients with neovascular AMD treated with bevacizumab.

[Anti-erythrocyte and anti-HLA immunization in hemoglobinopathies]

AIM

Evaluate the anti-erythrocyte and anti-HLA immunization rates in hemoglobinopathies.

PATIENTS AND METHODS

Cross-sectional study (October 2009-March 2010) on 83 patients followed for hemoglobinopathies. The irregular antibodies research is realized by two techniques: indirect Coombs and enzymatic technique on gel cards. The search for anti-HLA class I antibodies is done by complement dependent lymphocytotoxicity.

RESULTS

The mean age was 30 years (14-64 years), the sex ratio M/F is 0.84. Our series included 42 cases of sickle cell disease (29 homozygous sickle cell anemia and 13 sickle-thalassemia) and 41 cases of thalassemia syndromes (26 major and 15 intermediate). The anti-erythrocyte alloimmunization rate is 10.84% without difference between thalassemia syndromes and sickle cell disease. The autoimmunization rate (22.89%) is higher in thalassemia syndromes (41.46%) than in the sickle cell disease (7.14%) (P<0.001). The anti-HLA immunization rate is 31.6% without difference between thalassemia syndromes and sickle cell disease. The young age, transfusion at a young age and the total number of transfusions are the factors that increase the risk of anti-erythrocyte autoimmunization. No clinicobiological parameter does influence the anti-erythrocyte and anti-HLA alloimmunization. There is no significant association between anti-erythrocyte and anti-HLA immunization.

CONCLUSION

The erythrocyte and anti-HLA anti-immunization rates are high in our series. Preventive strategy is needed to ensure optimal blood safety.

Y402H polymorphism in complement factor H and age-related macular degeneration in the Tunisian population

To evaluate a possible association between the complement factor H (CFH) Y402H polymorphism and susceptibility to age-related macular degeneration (AMD) in the Tunisian population, as well as the impact of the genotype distribution among different phenotypes and the response to treatment with intravitreal bevacizumab, exon 9 of CFH was analyzed for the Y402H polymorphism by direct sequencing in 135 healthy controls and 127 sporadic unrelated AMD patients classified into the following groups: 12 atrophic AMD (group G1), 115 exudative AMD (G2) and 10 AMD patients who had fibrovascular scarring (G3) that did not allow a precise grading of the phenotype. Seventy patients in G2 were treated with 1.25 mg intravitreal bevacizumab at 6-week intervals until choroidal neovascularization (CNV) was no longer active. The frequency of the CFH 402H allele was significantly higher in AMD patients than in controls (p = 2.62 × 10(-16)). However, subgroup analysis does not reveal any association between the variant allele H and phenotypes of AMD or CNV. Also, there was no significant difference in response to bevacizumab treatment according to Y402H CFH genotype (p = 0.59). A strong association of the 402H allele with susceptibility to AMD in the Tunisian population was confirmed; however, this variant does not appear to be involved in the clinical progression of this disease or in the postintravitreal bevacizumab response.

Genetic polymorphisms of inflammatory molecules in Tunisian kidney transplantation

As chemokines and adhesion molecules play major roles in the process by which leukocytes are recruited from the bloodstream into sites of inflammation, genetic variations in the production or activity of molecules may influence susceptibility to acute rejection episodes. This study sought to determine the impact of recipient monocyte chemoattractant protein-1 (MCP-1), chemokine receptor (CCR2, CCR5), and adhesion molecule (ICAM-1, PECAM-1 and L/E selectin) polymorphisms on acute rejection after renal transplantation. We selected 169 healthy blood donors and 173 renal transplant recipients for analysis according to the presence or absence of graft rejection in the first 30 days after transplantation. Using molecular methods DNA was genotyped for 11 polymorphisms of these inflammatory molecules genes. Results were stratified by the incidence of rejection episodes and by human leukocyte antigen (HLA) mismatching. No association was detected between adhesion molecule polymorphisms and the incidence of acute rejection episodes. However, a significant risk of acute renal loss was observed among HLA-identical recipients who possessed the CCR2-64I allele (odds ratio 0.24, 95% confidence interval, 0.05 to 1.06; P=.035). In conclusion, the observed association of CCR2-64I with acute rejection episodes should be added to the spectrum of immunogenetic factors known to be involved in renal allograft rejection.

(AT) repeat in the 3' untranslated region of the CTLA-4 gene and susceptibility to acute allograft rejection in Tunisian renal transplantation

Allograft rejection is an immune response relying on the proliferation and the differentiation of T cells. CTLA-4 is a co-stimulatory molecule, expressed on activated T lymphocytes, which has been shown to play a crucial role in the down-regulation of T-cell activation. Herein, we have examined the impart of a genetic marker in the CTLA-4 gene on renal transplant outcomes. A cohort of 144 renal recipients and 100 healthy subjects were genotyped by the fragments analysis method using an automated sequencer. Patients were classified into two groups: Group I included 31 HLA-identical haplotype allograft recipients and Group II, 113 showing one or more HLA haplotype mismatches. Forty patients (27.78%) developed at least one acute rejection episode (ARE): 9 in Group I and 31 in Group II. Before transplantation, 20 patients were lymphocytotoxic antibodies (LCT) positive: 4 Group I, 2 of whom developed an ARE, and sixty in Group II, including 8 with an ARE. The occurrence of an ARE was associated with the presence of LCT before transplantation among the entire cohort of patients (P = .032) and among Group II (P = .037). The allelic frequencies of (AT)n polymorphism did not reveal significant differences between patients and controls. The most prevalent alleles were the 88 bp (51% in controls and 44.44% in patients) and the 106 bp (8% and 10.76%, respectively). We noticed an increase of the 120 bp allele frequency among patients who had undergone an ARE compared with those who did not display this complication (8.75% vs 3.85%). Likewise, among LCT-negative Group I, recipients the incidence of the 120 bp allele was higher in ARE than non-ARE patients. Although the differences were not statistically significant, we propose that the 120 bp allele of the CTLA-4 gene (AT)n microsatellite a predisposes to acute rejection episodes in renal transplantation.

Allograft renal rejection and chemokine polymorphism

Chemokines play a major role in the process by which leukocytes are recruited from the bloodstream into the sites of inflammation. Genes for the chemokine receptors CCR5, CCR2 and MCP-1 are characterized by functional polymorphisms implicated in transplant rejection. To investigate this association, we analyzed polymorphisms of CCR5-∆32, CCR5-59029-A/G, CCR2-V64I and MCP-1 G/A (-2518) in 173 renal transplant recipients and 169 healthy blood donors. The patients were classified in two groups: Group-1 (G-1) included 33 HLA-identical recipients and Group-2 (G-2) included 140 (one or more) mismatched graft recipients. Forty-two patients had developed acute rejection episodes (ARs): seven in G-1 and 35 in G-2. Thirteen G-2 patients developed chronic allograft dysfunction (CAD). The genotypic and allelic frequencies of all polymorphisms studied did not reveal significant differences between patients and controls and among G-1 and G-2 recipients. However, a significant risk of acute renal transplant rejection was found in G-1 patients who possessed the CCR2-64I allele (odds ratio 0.24, 95% confidence inter-val [CI], 0.05-1.06; P = 0.035). There was no significant association of this polymorphism and CAD. In conclusion, the observed association of CCR2-64I with AR should be added to the spectrum of immunogenetic factors known to be involved in allograft renal loss.

Association of chemokine and chemokine receptor polymorphisms with activity degree of IBD in Tunisian patients

Crohn's disease (CD) and ulcerative colitis (UC) have complex genetic background that is characterised by more than one susceptibility locus. To detect a possible association between the functional polymorphisms of the chemokine receptors CCR5, CCR2 and MCP-1 genes and susceptibility to CD and UC in Tunisian population, polymorphisms of CCR5-delta32, CCR5-59029-A/G, CCR2-V641 and MCP-1-2518-G/A were analysed in 194 Inflammatory bowel disease (IBD) patients and 169 healthy blood donors using PCR-RFLP and PCR-SSP methods. The patients were classified in 126 patients with CD and 68 patients with UC. The genotypic and allelic frequencies of all polymorphisms studied, did not reveal significant differences between patients and conrols and among CD and UC patients. However, analysis of CD patients revealed that those without homozygosous G/G genotype are more frequently in remission compared to those with this genotype (OR: 0.4, 95% CI: [0.174-0.928]; p = 0.03). Also, the frequency of the CCR2-641 muted allele was statistically higher in CD patients in remission disease than those in active form (OR: 0.267 95% CI: [0.09-0.78]; p = 0.01). Adjustment for known covariates factors (age, gender and immunosuppressive regimen) confirmed these univariate findings and revealed that the CCR5-59029-A/G and CCR2-V64I genotype were associated to remission form of CD (OR: 263; 95% CI: [1.01-6.80]; p = 0.047 and OR: 4.64; 95% CI: [1.01-21.31]; p = 0.049 respectively). In conclusion, the present study supports the involvement of chemokine receptor (CCR2 and CCR5) polymorphisms in activity degree of the IBD disease in Tunisian patients.

Soluble human leukocyte antigen-G (SHLA-G) in Tunisian kidney transplantation

To investigate the relationship between the soluble HLA-G (sHLA-G) and the appearance of acute renal rejection (AR) episodes we have quantify in this study the level of sHLA-G by enzyme-linked immunosotrbent assay in 42 kidney transplant patients classified in two groups: G1: 17patients with acute rejection (AR+) and G2: 25 patients without AR (AR-). To establish our normal sHLA-G ranges, serum samples from 18 healthy controls were tested. Pre-transplantation sHLA-G levels were significantly increased in patients (mean +/- standard error of the mean, 60.48 +/- 12.18 units/ml) than healthy subjects (19.11 +/- 4.9 units/ml) (p = 0.001). Although the difference was not statistically significant, G1 patients (AR+) revealed lower levels of sHLA-G (mean +/- standard error of the mean, 31.25 +/- 6.71 units/ml) compared to G2 patients (AR-) (53.43 +/- 1721 units/ml). Nevertheless, the course of total sHLA-G levels was nearly identical in patients with and without rejection. Nonparametric analysis revealed that pre-transplantation levels of sHLA-G < 18.00 units/ ml (sensitivity: 87.8% and specificity of 72.2%) were not related to rejection. Also, multivariate analysis regarding anti-HLA antibody status, recipient age and gender showed that sHLA-G could not be an independent risk factor for renal graft rejection. However, a higher sera levels of sHLA-G seemed to contribute to better kidney allograft survival rate after 10 years of follow-up (significance tendency: p = 0.091) as shown by the survival analysis. Because of the small number of subjects studied, these results must be treated with caution. A much larger cohort of kidney transplant patients according to acute rejection would seem necessary to confirm these findings.

Short- and long-term outcomes of living donors in Tunisia: a retrospective study

Despite initiatives to increase cadaveric donation, there is still a shortfall in donor organs. Kidneys from living donors now makes a significant contribution to increasing the number of organs available for transplantation in Tunisia. We performed a retrospective study of 405 kidney transplantations, including 321 (79.3%) from living donors performed from June 1986 to December 2007. We obtained information on only 162 (50.4%), namely, 64 men (39.5%) and 98 women (60.5%), whose mean age at the time of donation was 42.3 ± 12.2 years. Twelve (8.22%) perioperative complications occurred: wound infections (n = 4), pneumothorax (n = 4), phlebitis (n = 1), hematomas (n = 2), and urinary infection (n = 1). The mean follow-up period was 117.4 ± 74.4 months. Hypertension occurred in 42 donors (25.9%) with mean values of 134 ± 20 for systolic and 79 ± 10 for diastolic blood pressure. Twelve donors (7.4%) developed proteinuria (mean proteinuria, 0.08 ± 1.25 g/d). Renal insufficiency was found in 28 donors (19.44%), 2 of whom developed chronic renal failure requiring dialysis at intervals of 36 and 84 months. In both cases, we diagnosed a familial form of focal segmental glomerulosclerosis. Two donors (1.2%) died within 10 years after kidney donation due to senility. The relatively favorable outcomes suggest that living-donor kidney transplantation is an acceptable approach, in view of the superior results it yields in recipients. However, efforts to increase the number of cadaveric donors in Tunisia should be made. It is also important to develop a registry of long-term kidney function after kidney donation.

The PTPN22 C1858T (R620W) functional polymorphism in kidney transplantation

To investigate the association between kidney transplant rejection and PTPN22 (protein tyrosine phosphatase non-receptor 22) polymorphism, genomic DNA of 175 renal transplant recipients and 100 healthy blood donors were genotyped by restriction fragment length polymorphism-polymerase chain reaction. The patients were classified in two groups: G1 included 33 HLA-identical recipients and G2 included 142 with one or more HLA mismatches. Forty-nine patients developed an acute rejection episode (ARE): 8 in G1 and 41 in G2. The allelic frequencies of PTPN22 R620W revealed a significant difference between patients and controls. In fact, the W-allele was significantly more frequent in graft recipients than in blood donors (0.05 vs 0.01, P < .05). Furthermore, the frequency of this allele was increased in G1 patients with an ARE (0.188) compared with those without an ARE (0.040), but the difference was not statistically significant. Thus, we concluded that the PTPN22 W-variant allele could be involved in the susceptibility to acute allograft rejection in Tunisian kidney transplant patients.

Kidney transplantation: Charles Nicolle Hospital experience

The aim of our retrospective study was to analyze the short- and long-term follow-up of 298 renal transplantations performed between June 1986 and May 2005. All were first transplantations except 4 cases, with 54 from cadaveric and 244 from living donors. The recipients included 196 males and 102 females of overall mean age of 31.21 +/- 8.9 years (range, 16-61 years). A combination of prednisolone and azathioprine was presented for 212 patients or mycophenolate mofetil for 86 patients. Polyclonal or monoclonal antibodies were used as induction therapy in 183 cases. Cyclosporine was administered to 188 cases and tacrolimus only to 16. HLA matching was 0 mismatches (MM) in 65 cases; 1 or 2 MM in 113; 3 MM in 99; and > or =4 MM in 21. Acute tubular necrosis occurred in 45 cases. One hundred eighteen patients experienced at least 1 acute rejection episode: 102 cases (41.8%) among living and 16 (29.6%) among cadaveric kidneys donor (P = .0007). The actuarial patient and graft survival rates at 1, 5, 10, 15, and 20 years were 95.9%, 87.4%, 77.5%, 65.6%, and 60.8%, and 94.9%, 84.5%, 75.4%, 65.4%, and 53%, respectively. Sixty-three patients died and 72 patients returned to dialysis. Our results were comparable to experienced centers. However, the member of kidney transplantations does not match the increased number of patients on renal replacement therapy. It is advisable to promote obtaining organs from brain-dead donors.

Mannose binding lectin (+54) exon 1 gene polymorphism in Tunisian kidney transplant patients

Mannose-binding lectin (MBL), a collagen-like serum protein, is a key component of innate immunity. MBL binding to carbohydrates present on pathogens mediates lectin-dependent activation of the complement pathway. There is growing interest in the importance of innate immunity in host defense, particularly when adaptive immunity is compromised. Three single nucleotide polymorphisms (SNPs) of the MBL gene have been described in the first exon to be associated with low MBL serum concentrations as well as impaired MBL structure and function. Clinical studies have shown that these MBL SNPs are associated with increased susceptibility to infections, especially in immunocompromised patients. To investigate the association between acute kidney transplant rejection and polymorphism at codon 54 of the MBL gene, the DNA genomic of 133 renal transplant recipients and 117 healthy blood donors was analyzed by restriction fragment length polymorphism-polymerase chain reaction. The patients were classified into two groups: group 1 included 32 HLA-identical recipients and group 2, 101 one haplo-identical recipients. Forty-eight (36.1%) subjects had developed one or more acute rejection episodes (AREs) within the first 6 months after transplantation: 9 in group 1 (28.12%) and 39 in group 2 (38.61%). The genotype and allele frequencies of (+54) MBL gene polymorphism among patients and controls did not reveal a significant difference. However, the frequency of MBL-B mutant allele was increased among patients with AREs compared with those without AREs: group 1 (0.167 vs 0.065) versus group 2 (0.205 vs 0.105). Although the difference was not significant, perhaps because of the small number of patients, the MBL at codon (+54) polymorphism could be involved in the susceptibility of Tunisian kidney transplant recipients to acute allograft rejection episodes.

Prevalence of autoantibodies in a Tunisian cohort of hepatitis C virus infected dialysis patients

The hepatitis C virus (HCV) is the principal agent of viral chronic hepatitis. Cirrhosis and hepatocellular carcinoma are the major complications of this chronic infection. In haemodialysis, HCV infection remains a very frequent problem. Several autoimmune phenomena have been described during this infection. Two hundred haemodialysis patients, all of them anti-HCV (+), were included in this study to evaluate the frequency of Anti-Nuclear Autoantibodies (ANA), anti-cardiolipine antibodies (ACL), anti-smooth muscle antibodies (ASMA), anti-mitochondria antibodies (AMA), anti-thyroperoxydase antibodies (ATPO) and Rheumatoid Factor (RF) comparing them to healthy controls. Sixty eight serums (34%) patients were positive to at least one of the auto-antibodies tested. The difference between patients and controls was statistically significant. These markers were dominated by RF of the IgM isotype and ACL of the IgG isotype. Nevertheless, the positivity of ANA, ASMA, AMA and ATPO was not statistically different comparing to the controls. In addition, an association between the presence of the auto-antibodies and the viral replication was found suggesting that HCV is responsible for inducing these autoimmune phenomena.

CTLA-4 Exon 1 (+49) and Promoter (−318) Gene Polymorphisms in Kidney Transplantation

To investigate the association between kidney transplant rejection and the polymorphisms of CTLA-4 gene exon 1(+49) and promoter (-318), genomic DNA of 70 renal transplant recipients and 110 healthy blood donors were genotyped by PCR-RFLP and PCR-SSP, respectively. The patients were classified in two groups: G1 included 33 HLA-identical recipients and G2, 37 one haplo-identical recipients. Thirty-one recipients experienced an acute rejection episode: 10 in G1 and 21 in G2. Ten G2 patients developed chronic allograft dysfunction (CAD). Allelic frequencies and genotype distribution were similar among patients and controls. CTLA-4 exon 1 genotype A/A and CTLA-4 promoter genotype C/C were significantly higher among G2 patients with CAD than without CAD (P < .01). The distribution of CTLA-4 exon 1-promoter genes did not reach significance between graft recipients and controls. The genotype frequency of (G/G-C/C) was increased among controls (42.72%) compared with graft recipients (G1 and G2; 35.71%). CTLA-4 polymorphisms gene were associated with susceptibility to chronic allograft dysfunction.

Polymorphism of the renin-angiotensin-aldosterone system in patients with chronic allograft dysfunction

Polymorphism of the gene encoding components of the renin-angiotensin-aldosterone synthase system (RAAS) represents an area of intense research of cardiovascular disease associations. Numerous studies have addressed the role of RAAS gene polymorphisms in the development and progression of renal disease. Also, it has been reported that patient with ACE (DD) and angiotensinogen AGT (TT) genotypes are associated with chronic allograft dysfunction (CAD). We investigated the effects of gene polymorphisms of the renin-angiotensin-aldosterone system in renal transplant patients (81 males and 50 females; mean age 29.6+/-10.2 years). Genotypes were determined using polymerase chain reaction sequence specific primers and PCR followed by RFLP analysis. Renal allograft recipients with chronic allograft dysfunction had significantly higher frequencies of the MM genotype than those without CAD (P<0.05). The other genetic polymorphisms of the RAAS were not associated with CAD. This study proves that determination of AGT M235T genotype before transplantation may help identify patients who are at risk for chronic renal transplant dysfunction.

[Congenital heart block associated with maternal anti SSA/SSB antibodies :a report of four cases]

Congenital heart block (CHB) associated with maternal anti-SSA/SSB antibodies: a report of four cases. CHB detected in utero is strongly associated with maternal antibodies to SSA (Ro) and SSB (La). Their pathogenic role in the development of CHB has been established in several studies. The mothers of affected infants frequently had autoimmune disease (systemic lupus erythematosus, Sjögren's syndrome) or were entirely asymptomatic. It is very difficult to identify pregnant asymptomatic mothers carrying anti-SSA/SSB antibodies. We report four cases of infants born to asymptomatic mothers with anti-SSA/SSB antibodies, three of them developed isolated congenital cardiac heart block and one with no evidence of CHB. All three CHB are detected during pregnancy between 16 and 24 weeks of gestation. All maternal sera contained antibodies to SSA alone or the both SSA and SSB. Three of four subsequent pregnancies were complicated by heart block. One child affected died in utero. While the two other newborns with CHB required pacemaker insertion during the first 3 months of life. Although the association of anti-SSA/SSB with CHB is widely accepted, the precise mechanism by which these antibodies cause cardiac conduction abnormalities remains to be defined. Antibodies to SSA/SSB have been proposed to be a serologic marker for neonatal lupus syndrome and CHB. Fetal and neonatal diseases are presumed to be due to the transplacental passage of these IgG autoantibodies from the mother into the fetal circulation. Since these antibodies may have a pathogenic role in CHB, screening of infants with isolated CHB or neonatal lupus and their mothers for the presence of anti-SSA and anti-SSB is strongly recommended.

[Evaluation of an immunoblotting technique for the detection of anti-SSA and anti-SSB antibodies]

Immunoblotting and ELISA methods are now employed for the detection of anti Ro/SSA and anti La/SSB antibodies sometimes more often than double immunodiffusion or counter-immunoelectrophoresis. We have developed an immunoblotting technique for the detection of anti Ro/SSA and anti-La/SSB antibodies. This assay named IB-Hela, which uses a Hela cell extract, was compared with the double immunodiffusion technique like two other commercial immunoassays (Elisa test from Sanofi-diagnostic Pasteur and Line immunoassay from Innogenetics). This evaluation shows a good agreement especially in the case of Ro/SSA antibodies detection. IB-Hela seems to be useful in the La/SSB detection with a better sensitivity than the double immunodiffusion technique. We conclude that the IB Hela is helpful for the search for anti-Ro/SSA and anti-La/SSB autoantibodies and that it can be used as an alternative method to the classical techniques of immunodiffusion and counter immunoelectrophoresis.

[Detection and significance of cryoglobulins]

Cryoglobulins are immunoglobulins which reversibly precipitate at cold temperatures. They are usually accompanied with polymorphic clinical manifestations and biological abnormalities. Cryoglobulins are associated with various clinical disorders which include autoimmune diseases, lymphoproliferative and infectious disorders. Because of their low concentration, detection and quantitation of cryoglobulins need very rigorous conditions when collecting blood from patients.

[Anti-ribosomal antibodies during hepatitis C]

We report the case of a young Tunisian woman hospitalised for reasons of general ill health. A immunological check-up revealed autoimmune disturbances and in particular anti-ribosomal P antibodies. We discuss the possible relation of these antibodies to the hepatitis C infection from which the patient was also suffering.

Further evidence for the presence of anti-protein S autoantibodies in patients with systemic lupus erythematosus

Acquired protein S (PS) deficiency in systemic lupus erythematosus (SLE) has been previously reported, but its mechanism and its possible thrombotic role have not been established. The aim of our study was to provide further evidence for auto-immune PS deficiency in 27 Tunisian SLE patients, using PS-specific enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance technology (SPR). PS deficiencies for PS activity, free PS or total PS, respectively, were found in 19, 18 and 12 patients. A significant correlation (r= -0.475, P< 0.016) was found between free/total PS ratio and C4bBP levels, suggesting a role of inflammation in free PS deficiency. Immunoglobulin IgG antibodies to PS were detected in four patients by both ELISA and SPR, in six patients only by ELISA, and in two patients only by SPR. Signals for anti-PS IgG by ELISA and SPR were, however, significantly correlated (r = 0.549, P = 0.003). These results suggest that an auto-immune mechanism could account for low PS activity in patients with SLE. Auto-antibodies to PS may form immune complexes, inducing increased clearance of PS or interfering with the protein C-protein S system.

Hepatitis C virus antibodies in dialysis patients in Tunisia: a single center study

Fifty-eight patients on maintenance hemodialysis in a dialysis unit at Tunis, Tunisia were tested for anti-hepatitis C virus (anti-HCV) antibodies by second generation ELISA test, and for HCV-RNA by nested reverse transcriptase polymerase chain reaction (RT-PCR) of 5' non-coding region. Specificity of the antibodies was confirmed by immunoblot test. HCV genotype was defined using INNO-LIPA test. Twenty-seven out of 58 patients (46.5%) were reactive by ELISA. Transaminase levels were assessed over a six-month period and showed normal average values. Fourteen of the 27 anti-HCV positive patients (51%) were positive by RT-PCR. Type 1b HCV genotype was the most prevalent, seen in all the dialysis patients and one patient in addition, was co-infected with genotype 4. There was a significant correlation between the duration on dialysis (over five years) and the prevalence of anti-HCV-positive patients (P< 0.005) while no correlation existed between the number of blood transfusions and the presence of anti-HCV antibodies. The present study illustrates the high prevalence of HCV infection among Tunisian dialysis patients (51%) and indicates that the spread may be nosocomial rather than transfusion-related.

[Detection of hepatitis C virus in the general population of Tunisia]

We searched for antibodies to hepatitis C in a sample of 3079 Tunisians in the suburban area of Tunis. 30 people were positive by ELISA and 22 were confirmed by immunoblotting. This result represents a prevalence of 0.71% which is close to the values reported in European countries of the Mediterranean area.

[Interference of factor VIII excess on the detection of lupus anticoagulants by the activated partial thromboplastin time]

Antiphospholipids antibodies (AAP) were investigated in plasma of 62 patients with systemic lupus erythematosus, and studied for the possible interference of the excess in factor VIIIc-Von Willebrand factor (VWF-VIIIc) complex in the detection of lupus anticoagulants (LA) by the activated partial thromboplastin time (APTT). We used four commercial reagents and noted that each one exhibited a different level of sensitivity of LA; the most sensitive one allowed the detection of 16 LA positive plasmas while the less sensitive reagent detected only 6 positives. The Elisa test for IgG and IgM AAP detection was positive in 25 out of 62 plasmas (40%). Comparison of the Von Willebrand factor antigen level and the APTT values showed a significant negative corrélation with 2 reagents (r = 0.369, p < 0.01 and r = 0.272, p < 0.05 respectively) that were also the less sensitive to LA. The interference of an excess in VWF-VIIIc complex was further studied by the addition of purified factor VIII in 3 LA positive plasmas. Our results suggests that an excess of factor VIIIc could lead to false negative LA, using certain APTT reagents. We conclude that a more accurate LA detection require: sensitive reagents, a pool of normal plasmas selected with normal factor VIII level, as well as repeated testing of blood sampling withdrawn away of an inflammatory process to avoid false negative LA detection.

[Value of the search for anticardiolipin antibodies during the course of systemic lupus erythematosus]

The anticardiolipin antibodies (aCL) are acquired inhibiting antibodies of the coagulation process. They interfere with the anionic phospholipids of the cellular membranous. These are frequently associated to the autoimmune diseases, especially the systemic lupus erythematosus (SLE), they expose the patient to thrombotic complications. In order to define the possible and prognostic predictive value of these aCL, a sequential research of these antibodies was performed on 12 patients suffering from SLE since 2 to 11 years. An average of one sample per year was drawn, either during an attack or in a routine control check. The detection of these IgG aCL did not appear to be related with be course of the disease. In fact, 3 of our patients, ill since respectively 2, 7 and 11 years, never showed any aCL. These aCL were positive during an attack in 80% of the cases. This positivity was associated to vascular thrombosis (2 cases), and cutaneous vascularity (6 cases) and, in one case, the presence of aCL was linked to inutero fetal death due to retruplacentary hematoma. This study confirms the association between aCL and thrombosis during systemic lupus erythematosus.

Common idiotypes expressed on human, monoclonal, abnormal immunoglobulins and cryoglobulins with polyreactive autoantibody activities

Several human monoclonal immunoglobulins with the same autoantibody activity have been shown to have cross-reactive idiotypes (CRI). In this study, using polyclonal anti-idiotypic antibodies, we found that 28% of human monoclonal immunoglobulins with polyreactive autoantibody activity from myeloma, Waldenström's macroglobulinaemia and cryoglobulinaemia patients shared common idiotype(s). Furthermore, the latter were expressed on human and murine natural MoAbs (respectively in 12% and 22% of the clones tested) and on human IgG preparations used for therapeutic intravenous injections (IVIg) and which contain natural antibodies. These findings suggest that monoclonal immunoglobulins could arise from the proliferation of a clone that normally produces a natural antibody. The existence of common idiotype(s) between monoclonal immunoglobulins and IVIg could be relevant to the improvement noted after treatment with IVIg in patients suffering from peripheral neuropathies associated with monoclonal gammopathy.

Pemphigus foliaceus in young women. An endemic focus in the Sousse area of Tunisia

BACKGROUND AND DESIGN

With the exception of some areas in Brazil, pemphigus is an exceptional disease. Several previous observations suggested that pemphigus foliaceus occurred more frequently than expected in Tunisia. To confirm these observations, a 15-month prospective survey was undertaken at the University Hospital of Sousse in Tunisia.

RESULTS

During the survey, 23 patients with pemphigus were observed. Twenty of 23 cases were of pemphigus foliaceus that affected only young women. Seven patients had the clinical features of pemphigus herpetiformis. The estimated incidence of pemphigus foliaceus in the Sousse area was four new cases per million inhabitants per year, far above European or North American incidence but lower than the incidence in the most severely affected areas in Brazil. The high prevalence of the herpetiform clinical variant, the young age, the feminine exclusivity, and the absence of familial cases differentiated this Tunisian pemphigus both from pemphigus foliaceus observed in Europe and North America and from the Brazilian fogo selvagem. No etiologic factor was identified.

CONCLUSIONS

This study suggests the existence in Tunisia (and possibly in all North Africa) of an endemic form of pemphigus foliaceus restricted to young women.

[Lupus in children in Tunisia]

In this study, we have analyzed the clinical and serological features related to 16 Tunisian children in whom diagnosis of systemic lupus erythematosus was made before or at the age of 15. Renal involvement was found in 75% of cases and renal biopsies have mostly revealed severe histologic patterns. All of the patients who have been followed received corticosteroids and in some cases required additional cytotoxic drugs in order to control disease activity. Five children died in a context of a renal failure. This study of childhood lupus in Tunisia confirms that the clinical course of this disease in children is often aggressive.

C4 polymorphism in multiplex families with insulin dependent diabetes in the Tunisian population: Standard C4 typing methods and RFLP analysis

The polymorphism of C4A and C4B genes was investigated in Tunisian patients with insulin dependent diabetes (IDDM) and compared to family members (sibs) and to healthy controls. Multiplex families were analysed. A significant increase in C4AQO (26.86% vs 6.90%) and C4BQO (40.29% vs 8.28%) phenotypes was noted in IDDM patients compared with controls. Using RFLP analysis, we confirmed the high frequency of C4 null alleles. We also observed that most of these alleles were genes deleted in IDDM patients (72.23% vs 20% for CA4QO and 74.07% vs 16.70% for C4BQO). A significant decrease in the C4B long (14.92% vs 67.12%) form of the gene was also demonstrated by RFLP analysis compared with controls. Two haplotypes were frequently associated with IDDM patients in whom the C4A and C4B were deleted genes.