Autoantibodies against complement proteins in patients with antiphospholipid syndrome: Prevalence and clinical associations

Seventy-seven patients with antiphospholipid syndrome were tested for autoantibodies against C1q, C3, FB, FH, and C4bp. Fifty-seven patients had at least one anti-complement antibody. IgM anti-FH positivity was associated with thrombosis when anti-C3 and anti-FB were, negatively or positively, associated with various noncriteria manifestations of antiphospholipid syndrome.

Disease patterns and specific trajectories of anti-MDA5-related disease: a multicentre retrospective study of 70 adult patients

Introduction

This study aimed to provide an updated analysis of the different prognostic trajectories of patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibodies.

Methods

Among a cohort of 70 patients, baseline characteristics and phenotypes, treatments and outcomes were analyzed. A Cox proportional hazards model was used to identify factors associated with poor outcomes, i.e., death or progressive disease at the last follow-up.

Results

Among the 70 patients, 45 were women, and 54 were Caucasian. A dermatologic involvement was observed in 58 (83%) patients, including 40 with MDA5 vasculopathy-related skin lesions. Muscular involvement was observed in 39 (56%) patients. Interstitial lung disease (ILD) was observed at baseline in 52 (74%) patients, including 23 (44%) who developed rapidly progressive (RP) ILD. Seven (10%) patients showed thromboembolic complications within the first weeks of diagnosis, and eight (11%) other patients developed a malignancy (4 before the diagnosis of anti-MDA5 disease). Poor outcomes were observed in 28 (40%) patients, including 13 (19%) deaths. Among the 23 patients with RP-ILD, 19 (79%) showed poor outcomes, including 12 (63%) who died. In multivariate analyses, RP-ILD (hazard ratio (HR), 95% CI: 8.24 [3.21-22], p<0.0001), the occurrence of thromboembolic events (HR: 5.22 [1.61-14.77], p=0.008) and the presence of any malignancy (HR: 19.73 [6.67-60], p<0.0001) were the three factors independently associated with poor outcomes.

Discussion

This new independent cohort confirms the presence of different clinical phenotypes of anti-MDA5 diseases at baseline and the poor prognosis associated with RP-ILD. Thromboembolic events and malignancies were also identified as prognostic factors.

Early infectious risk in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis according to remission-induction therapy

OBJECTIVE

Few comparative data exist on early infections secondary to remission-induction therapy (RIT) with rituximab (RTX) versus cyclophosphamide (CYC) in newly diagnosed anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients. We compared and analysed the rates and predictors of severe infection in such patients within the first 6 months following RIT.

METHOD

From the Caen University Hospital databases, we included all consecutive adults newly diagnosed with ANCA-positive granulomatosis with polyangiitis or microscopic polyangiitis between January 2006 and December 2019. We compared rates of survival without severe infection and survival without infections of any severity within 6 months of RIT and used a multivariate Cox analysis to identify predictors of infection.

RESULTS

We included 145 patients, 27 in the RTX and 118 in the CYC group. Patients in the RTX group more frequently had pneumococcal vaccination (p < 0.01) and creatinine < 150 µmol/L; other characteristics were comparable between the two groups. Overall, 37 severe infections and 65 infections of any severity were recorded. Rates of survival without severe infection were similar in both groups (p = 0.69), but survival without infections of any severity was lower in the RTX group (p = 0.005). In multivariate analysis, risk factors at diagnosis for severe infections included chronic urinary tract disease, dialysis, and absence of trimethoprim-sulfamethoxazole prophylaxis (p < 0.01 each).

CONCLUSIONS

Within 6 months of RIT, rates of survival without severe infection were similar in newly diagnosed ANCA-positive AAV patients treated with RTX or CYC, but survival rates without infections of any severity appeared to be lower with RTX treatment.

The diagnostic challenge of patients with anti-U1-RNP antibodies

Anti-U1-RNP antibodies are necessary for the diagnosis of mixed connective tissue disease (MCTD), but they are also prevalent in other connective tissue diseases, especially systemic lupus erythematosus (SLE), from which distinction remains challenging. We aimed to describe the presentation and outcome of patients with anti-U1-RNP antibodies and to identify factors to distinguish MCTD from SLE. We retrospectively applied the criteria sets for MCTD, SLE, systemic sclerosis (SSc) and rheumatoid arthritis (RA) to all patients displaying anti-U1-RNP antibodies in the hospital of Caen from 2000 to 2020. Thirty-six patients were included in the analysis. Eighteen patients (50%) satisfied at least one of the MCTD classifications, 11 of whom (61%) also met 2019 ACR/EULAR criteria for SLE. Twelve other patients only met SLE without MCTD criteria, and a total of 23 patients (64%) met SLE criteria. The most frequent manifestations included Raynaud's phenomenon (RP, 91%) and arthralgia (67%). We compared the characteristics of patients meeting only the MCTD (n = 7), SLE (n = 12), or both (n = 11) criteria. Patients meeting the MCTD criteria were more likely to display SSc features, including sclerodactyly (p < 0.01), swollen hands (p < 0.01), RP (p = 0.04) and esophageal reflux (p < 0.01). The presence of scleroderma features (swollen hands, sclerodactyly, gastro-oesophageal reflux), was significantly associated with the diagnosis of MCTD. Conversely, the absence of those manifestations suggested the diagnosis of another definite connective tissue disease, especially SLE.

Validation of an anti-α-Gal IgE fluoroenzyme-immunoassay for the screening of patients at risk of severe anaphylaxis to cetuximab

BACKGROUND

The link between immediate hypersensitivity reactions (HSR) following the first cetuximab infusion and the IgE sensitization against anti-galactose-α-1,3-galactose (α-Gal) is now well-established. An automated Fluoroenzyme-Immunoassay (FEIA) is available and may facilitate the screening of patients with anti-α-Gal IgE before treatment.

METHODS

This study aimed to evaluate its performances as compared to a previously validated anti-cetuximab IgE ELISA, using 185 samples from two previously studied cohorts.

RESULTS

Despite 21.1% of discrepancies between the two techniques, FEIA discriminated better positive patients and similarly negative ones with a ≥ 0.525 kU_A/L threshold. Sensitivity was 87.5% for both tests, specificity was better for FEIA (96.3% vs ELISA: 82.1%). FEIA had a higher positive likelihood ratio (23.9 vs ELISA: 4.89) and a similar negative likelihood ratio (0.13 vs ELISA: 0.15). In our population, the risk of severe HSR following a positive test was higher with FEIA (56.7% vs ELISA: 19.6%) and similar following a negative test (0.7% vs ELISA: 0.8%).

CONCLUSION

Although the predictive value of the IgE screening before cetuximab infusion remains discussed, this automated commercial test can identify high-risk patients and is suitable for routine use in laboratories. It could help avoiding cetuximab-induced HSR by a systematic anti-α-Gal IgE screening before treatment.

AB0615 Clinical impact of ceruloplasmin levels at ANCA-associated vasculitis diagnosis

Background

Myeloperoxidase (MPO) plays a major role in loss of immunological tolerance leading to tissue destruction in ANCA-associated vasculitis (AAV). Ceruloplasmin is a protein with antiproteinase and antioxidant properties that inhibits MPO activity. Whether serum level of ceruloplasmin at AAV diagnosis has an impact is unknown.

Objectives

The objective of this study was to evaluate the prognostic impact of serum level of ceruloplasmin at diagnosis in patients with granulomatosis with polyangiitis or microscopic polyangiitis.

Methods

We conducted a retrospective unicentric study at Caen University Hospital, involving consecutive adult patients with granulomatosis with polyangiitis or microscopic polyangiitis between 2010 and 2021 who had available serum at diagnosis. Data was collected using the health records.

Ceruloplasmin was measured by standardized nephelometry (normal values: 0.15 – 0.50 g/L). Patients in each subgroup (whole cohort, microscopic polyangiitis and anti-MPO patients) were divided into two groups based on the median serum level of ceruloplasmin.

We estimated survival using the Kaplan-Meier survival curve, and between-group differences were evaluated by the log-rank test. The study was approved by the local ethics committee of Caen University Hospital (n° 1947).

Results

Ninety-two patients were included, 46 (50%) granulomatosis with polyangiitis (41 anti-proteinase 3 and 5 anti-MPO) and 46 (50%) microscopic polyangiitis (45 anti-MPO and 1 anti-proteinase 3). The median level of ceruloplasmin was 0.44 g/L. No significant differences in the clinical presentation were observed between patients in the two groups (p>0.05). We observed 9 (19.6%) deaths in the low ceruloplasmin group and 5 (10.9%) in the high ceruloplasmin group (p=0.39). Vasculitis relapse occurred in 10/46 patients (22%) and 11/46 patients (24%) (p=1), renal failure leading to dialysis and/or renal transplant in 6/46 patients (13%) and 8/46 patients (17%) (p=0.77), respectively. No significant difference in survival was found (p=0.07). The same analyses were performed between the low and the high ceruloplasmin group with the microscopic polyangiitis subgroup (n=46), and no significant differences were found (p>0.05). However, within the anti-MPO subgroup (n=50), the survival was worse in the low ceruloplasmin group (p=0.03).

Conclusion

In anti-MPO AAV patients, serum level of ceruloplasmin at diagnosis seems to be associated with a significant impact on survival.

References

[1]Baskin E, et al. Ceruloplasmin levels in antineutrophil cytoplasmic antibody-positive patients. Pediatr Nephrol. 2002;17(11):917–9.

[2]Ara J, et al. Ceruloplasmin in small vessel vasculitis. Nephrol Dial Transplant. févr 1999;14(2):515-7.

isclosure of Interests: None declared

POS0831 EARLY INFECTIOUS RISK IN PATIENTS WITH NEWLY-DIAGNOSED ANTI-NEUTROPHILCYTOPLASMIC ANTIBODY-ASSOCIATED VASCULITIS ACCORDING TO THE REMISSION-INDUCTIONTHERAPY: A FRENCH MONOCENTRIC RETROSPECTIVE STUDY INCLUDING 145 PATIENTS

Background:

Few comparative data exist on early infections secondary to remission-induction therapy (RIT) with rituximab versus cyclophosphamide in newly-diagnosed ANCA-associated vasculitis (AAV) patients.

Objectives:

We compared and analyzed the rate and predictors of severe infections in such patients within the first six months following RIT.

Methods:

We included, from the databases of Caen University Hospital, all consecutive adults newly-diagnosed with granulomatosis with polyangiitis or microscopic polyangiitis between January 2006 and December 2019. We compared the survival without severe infections (WSI) and the survival without infection of any severity (WIOAS) within 6 months from the RIT, and used a multivariate cox analysis to identify predictors of infection.

Results:

We included 145 patients, 27 in rituximab group and 118 in cyclophosphamide group. Patients in the rituximab group more frequently had pneumococcal vaccination (p<0.01) and creatinine level <150 µmol/L, while other characteristics, including Birmingham Vasculitis Activity Score, were comparable between both groups.

Overall, 37 severe infections and 65 infections of any severity were recorded. The survival WSI was similar in both groups (p=0.69), but survival WIOAS was lower in rituximab group (p=0.005).

In multivariate analysis, risk factors at diagnosis for severe infections were chronic urinary tract disease, dialysis and absence of prophylaxis with trimethoprim-sulfamethoxazole (p<0.01 each).

Conclusion:

The survival WIS within the 6 months following RIT was similar in patients with newly-diagnosed AAV treated by rituximab or cyclophosphamide, but survival WIOAS appeared to be lower within the 6 months following rituximab despite a better pneumococcal vaccination coverage.

Figure 1.

Comparison of the 6-month survival without severe infection (A) or without infection of any severity (B) in patients with newly-diagnosed ANCA-associated vasculitis treated by rituximab or cyclophosphamide

Disclosure of Interests:

None declared

Natalizumab in Multiple Sclerosis Treatment: From Biological Effects to Immune Monitoring

Multiple sclerosis is a chronic demyelinating disease of the central nervous system (CNS) with an autoimmune component. Among the recent disease-modifying treatments available, Natalizumab, a monoclonal antibody directed against the alpha chain of the VLA-4 integrin (CD49d), is a potent inhibitor of cell migration toward the tissues including CNS. It potently reduces relapses and active brain lesions in the relapsing remitting form of the disease. However, it has also been associated with a severe infectious complication, the progressive multifocal leukoencephalitis (PML). Using the standard protocol with an injection every 4 weeks it has been shown by a close monitoring of the drug that trough levels soon reach a plateau with an almost saturation of the target cell receptor as well as a down modulation of this receptor. In this review, mechanisms of action involved in therapeutic efficacy as well as in PML risk will be discussed. Furthermore the interest of a biological monitoring that may be helpful to rapidly adapt treatment is presented. Indeed, development of anti-NAT antibodies, although sometimes unapparent, can be detected indirectly by normalization of CD49d expression on circulating mononuclear cells and might require to switch to another drug. On the other hand a stable modulation of CD49d expression might be useful to follow the circulating NAT levels and apply an extended interval dose scheme that could contribute to limiting the risk of PML.

Clinical impact of subgrouping ANCA-associated vasculitis according to antibody specificity beyond the clinicopathological classification

OBJECTIVES

In ANCA-associated vasculitis (AAV), classifications have emerged to individualize homogeneous clinical and outcomes patterns, including the recently defined anti-MPO granulomatosis with polyangiitis (GPA) subgroup. This study aimed to retrospectively evaluate the impacts of re-classification based on clinicopathological criteria and/or ANCA specificity.

METHODS

A retrospective monocentric study conducted at Caen University Hospital led to the identification of PR3 or MPO-ANCA AAV patients from January 2000 or September 2011, respectively, to June 2016. Eosinophilic GPA patients were excluded. AAVs were thereby also classified either as GPA or microscopic polyangiitis (MPA) according to the European Medicines Agency vasculitis algorithm.

RESULTS

A total of 150 AAV patients were included (94 GPA, 56 MPA; 87 anti-PR3 and 63 anti-MPO patients). GPA patients exhibited a worse relapse-free survival but a better renal survival (P < 0.001 and P = 0.021, respectively) than MPA patients. Overall, relapse-free and renal survival rates were similar between anti-PR3 and anti-MPO patients (P = 0.35, 0.17 and 0.15, respectively). Similarly, the prognosis was identical between anti-MPO MPA patients and anti-PR3 MPA patients (P = 0.33, 0.19 and 0.65, respectively), and between anti-MPO GPA patients and anti-PR3 GPA patients (P = 0.06, 0.99 and 0.64, respectively). Moreover, anti-PR3 GPA and anti-MPO GPA patients exhibited no differences in clinical manifestations or BVAS score.

CONCLUSION

Clinicopathological classification appeared to be the strongest criterion for distinguishing among homogeneous prognoses of AAV. Individualizing the anti-MPO GPA subgroup does not appear to bring additional value to clinical practice, but multicentre studies are required to confirm this trend.

Clinical Effect of Alpha-1 Antitrypsin Deficiency in Antineutrophil Cytoplasmic Antibody-associated Vasculitis: Results from a French Retrospective Monocentric Cohort

OBJECTIVE

Deficiency in alpha-1 antitrypsin (AAT) is a possible pathogenic cofactor in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). However, the clinical effect of AAT deficiency remains poorly established in this setting. This study aimed to describe the clinical phenotypes and outcomes of AAV according to AAT phenotypes.

METHODS

This study was conducted retrospectively at Caen University Hospital and included all consecutive granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) patients with positive proteinase 3-ANCA or myeloperoxidase-ANCA, from January 2000 or September 2011, respectively, to June 2016. AAT dosage (nephelometry) and phenotyping (isoelectric focusing in agarose gel) were performed.

RESULTS

Among the 142 patients with AAV, including 88 GPA and 54 MPA, 102 (72%) had the MM phenotype, 5 (4%) had a nonpolymerogenic M-variant phenotype, 18 (13%) had the deficient allele MZ, 12 (8%) had MS, 2 (1%) had ZZ, 2 (1%) had SZ, and 1 (1%) had SS. M, Z, and S allele frequencies were 84%, 8%, and 6%, respectively. No association was observed between AAT deficiency and ANCA subtype or AAV phenotype, except for intraalveolar hemorrhage (IAH), which was more frequent in patients harboring at least 1 of the deficient Z or S alleles than in those without any deficient alleles (p < 0.01). Global, renal, or relapse-free survival rates were similar for all subgroups.

CONCLUSION

This study shows that AAT deficiency confers, independently of ANCA subtype, a higher risk of IAH. Prospective studies are required to refine these data and to assess the need for replacement therapy in AAT-deficient patients with AAV.

Hypocomplementemia is associated with worse renal survival in ANCA-positive granulomatosis with polyangiitis and microscopic polyangiitis

Recent data suggest the existence of a complement alternative pathway activation in the pathogenesis of antineutrophilic cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a condition that remains poorly understood. This study aims to assess the clinical characteristics and outcomes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) patients with regard to their plasma complement levels at diagnosis. A retrospective monocentric study carried out at Caen University Hospital led to the identification of proteinase-3- or myeloperoxidase-ANCA-positive GPA and MPA patients from January 2000 to June 2016 and from September 2011 to June 2016, respectively. All patients with available C3 and C4 levels at diagnosis were included. Patients were categorized in the hypocomplementemia group if their C3 and/or C4 levels at diagnosis were below the lower limit of the normal range. Among the 76 AAV patients (43 GPA, 33 MPA), 4 (5%) had hypocomplementemia, and the 72 remaining patients exhibited normal plasma complement levels. All 4 hypocomplementemia patients had renal involvement. Hypocomplementemia was followed in 1 patient whose post-treatment complement level normalized within 1 month. Among all clinical and ANCA specificity, including relapse-free survival (p = 0.093), only overall and renal survival rates were significantly lower in the hypocomplementemia group (p = 0.0011 and p<0.001, respectively). Hypocomplementemia with low C3 and/or C4 levels at GPA or MPA diagnosis may be responsible for worse survival and renal prognosis. These results argue for larger and prospective studies to better determine the epidemiology of the disease and to assess complement-targeting therapy in these patients.

Utility of serum anti-cetuximab immunoglobulin E levels to identify patients at a high risk of severe hypersensitivity reaction to cetuximab

AIM

Cetuximab is an anti-epidermal growth factor receptor antibody used for the treatment of metastatic colorectal cancer and head and neck cancer. Hypersensitivity reactions (HSRs) are associated with cetuximab use. The aim of the study was to evaluate the utility of anti-cetuximab immunoglobulin E (IgE) detection in order to identify patients at risk of HSR to cetuximab.

METHODS

We included patients ready to receive a first cetuximab infusion in a prospective cohort carried out at nine French centres. Pretreatment anti-cetuximab IgE levels were measured. We compared the proportion of severe HSRs in the low anti-cetuximab IgE levels (≤29 IgE arbitrary units) subgroup with that in a historical cohort of 213 patients extracted from a previous study.

RESULTS

Of the 301 assessable patients (mean age: 60.9 ± 9.3 years, head-and-neck cancer: 77%), 66 patients (22%) had high anti-cetuximab IgE levels, and 247 patients received cetuximab (including 38 with high anti-cetuximab levels). Severe HSRs occurred in eight patients (five grade 3 and three grade 4). The proportion of severe HSRs was lower in the low anti-cetuximab IgE levels subgroup vs. the historical cohort (3/209 [1.4%] vs. 11/213 [5.2%], odds ratio, 0.27, 95% confidence interval, 0.07-0.97), and higher in high vs. low anti-cetuximab IgE levels subgroup (5/38 [13.2%] vs. 3/209 [1.4%]; odds ratio, 10.4, 95% confidence interval, 2.4-45.6). Patients with severe HSRs had higher anti-cetuximab IgE levels than patients without reaction (median, 45 vs. 2 IgE arbitrary units, P = 0.006).

CONCLUSIONS

Detection of pretreatment anti-cetuximab IgE is feasible and helpful to identify patients at risk of severe cetuximab-induced HSRs.

Diagnostic procedure after an immediate hypersensitivity reaction in the operating room

The diagnosis of a perioperative allergic reaction is based on clinical features associated with a suggestive timeline, the exclusion of other diagnoses, elevated concentrations of degranulation markers (histamine, tryptase), and positive allergy assessments (skin tests, specific IgE). After initiating appropriate treatment, the anesthesiologist should take blood samples to measure histamine and tryptase concentrations just after the reaction and repeat them 1-2hours later to validate the diagnosis of immediate hypersensitivity. A delayed measurement of basal tryptase is useful to rule out mastocytosis and to interpret moderate tryptase levels. The anesthesiologist must inform the patient of the reaction to obtain adhesion and consent to subsequent investigations and must record the timing of the reaction and of the blood sampling, the possible causal agents, and the treatment administered. These data must be shared with the laboratory and the allergist. An adverse drug reaction report must be filed. The gold standard for allergy assessment is skin testing. These tests should be done in an appropriate facility, with experienced staff and in compliance with current guidelines. Specific IgE assays and cellular assays can help when clinical features and skin tests are discordant. Provocation tests are sometimes required. After allergy assessment, the safest protocol for subsequent anesthesia is determined in collaboration with the anesthesiologist. The patient must be informed and carry an allergy alert card.

Risk factors associated with hypersensitivity reactions to cetuximab: anti-cetuximab IgE detection as screening test

AIM

To describe the factors associated with a high risk of a hypersensitivity reaction to cetuximab.

PATIENTS & METHODS

We retrospectively studied a cohort of patients living in Normandy (France) treated with cetuximab.

RESULTS

Among the 229 treated patients, 24 (10.5%) had a hypersensitivity reaction to cetuximab, including 11 grade 3-5 reactions. Detection of anti-cetuximab IgE could be performed in 108 patients. Anti-cetuximab IgE was found in 13 of 17 patients (76.5%) who had a hypersensitivity reaction to cetuximab compared with 17 of 91 control patients (18.7%; adjusted odds ratio: 14.99; 95% CI: 3.59-62.63). No clinical criteria predicted the risk of allergy to cetuximab.

CONCLUSION

Anti-cetuximab IgE may help physicians identify patients at risk of a hypersensitivity reaction to cetuximab.

The importance of EN ISO 15189 accreditation of allergen-specific IgE determination for reliable in vitro allergy diagnosis

BACKGROUND

Allergen-specific serum immunoglobulin E detection and quantification have become an important step in allergy diagnosis and follow-up. In line with the current trend of laboratory test accreditation to international standards, we set out to design and assess an accreditation procedure for allergen-specific serum IgE.

METHODS

Method validation according to the accreditation procedure under the EN ISO 15189 standard was carried out for allergen-specific immunoglobulin E determination using the fluoroimmunoenzymatic method ImmunoCAP(®) (ThermoFisher). Data were produced by 25 hospital laboratories in France. A total of 29 allergen specificities including mixes, extracts, and molecular allergens were assayed. Allergen-specific serum immunoglobulin E concentrations ranged from 0.1 to 100 kUA /l.

RESULTS

Repeatability, reproducibility, and accuracy results fulfilled method validation criteria for automated laboratory tests and proved similar irrespective of the allergen specificity, allergen-specific serum immunoglobulin E concentration, or individual laboratory.

CONCLUSION

Allergen-specific serum immunoglobulin E determination with the fluoroimmunoenzymatic method ImmunoCAP(®) is a highly repeatable, reproducible, and accurate method which may be considered as a single analyte assay in view of the EN ISO 15189 accreditation procedure.

Case Report About Fatal or Near-Fatal Hypersensitivity Reactions to Cetuximab: Anticetuximab IgE as a Valuable Screening Test

Hypersensitivity reactions are a classic side effect of cetuximab. We report the cases of three patients who developed life-threatening hypersensitivity to cetuximab, which could have been predicted by assessing the concentration of serum anticetuximab immunoglobulin (Ig)E. The anticetuximab IgE concentration could be an interesting test to predict which patients are at risk of experiencing severe hypersensitivity reactions to cetuximab.

CD49d expression as a promising biomarker to monitor natalizumab efficacy

Natalizumab (Tysabri™), a monoclonal antibody against the α4-integrin of VLA-4 (CD49d) antigen of leukocytes, is highly effective in multiple sclerosis (MS). The most common reason for treatment failure is the development of neutralizing antibodies (NAbs). According to health authorities Nabs testing is recommended in case of relapse or repeated infusion reactions. However NAbs may develop in clinically asymptomatic patients. In this study we investigated if CD49d expression could serve as a biomarker of natalizumab bioavailability and treatment response. In a cohort of 49 natalizumab treated relapsing-remitting MS, followed over 2 years, CD49d expression was determined on peripheral blood mononuclear cells (PBMCs) before each infusion and compared to NAbs and serum natalizumab levels. In a majority of patients (41/49) the CD49d expression in PBMCs was strongly inhibited (>50%) after the first infusion and maintained at low levels throughout the treatment period. In contrast, in eight patients (16%) there was an early recovery of CD49d expression to pre-treatment levels related to NABs development. While three cases experienced hypersensitivity reactions, three others were identified solely on the basis of an undiminished level of CD49d, with neither infusion reaction nor clinical worsening. These 3 patients had very high levels of NAbs and no detectable serum natalizumab. Two additional patients had early but transient recovery of CD49d expression. These patients had low levels of transient Nabs and returned to significant CD49d inhibition after few natalizumab infusions. We suggest that monitoring of CD49d expression can be used as a surrogate biomarker of natalizumab efficiency. If the CD49d expression is sustained at pre-treatment levels, patients should be tested for persistent NAbs and considered for treatment interruption.

Anti-cetuximab IgE ELISA for identification of patients at a high risk of cetuximab-induced anaphylaxis

Cetuximab, a chimeric mouse-human IgG1 monoclonal antibody against the epidermal growth factor receptor, has proven effective in the treatment of metastatic colorectal cancer and squamous cell carcinoma of the head and neck. However, a high incidence of immediate hypersensitivity reactions (HSR) to cetuximab after the first infusion has been observed. We have developed a test for identification of patients likely to show treatment-related HSR to cetuximab. An enzyme-linked immunosorbent assay (ELISA) for detecting anti-cetuximab IgEs was developed and tested on serum samples collected from cancer patients before start of cetuximab treatment, and from healthy blood donors. Similar levels of anti-cetuximab IgE were detected in pre-treatment patient sera (24/92, 26.1%) and sera from healthy blood donors (33/117, 28.2%). HSR were observed in 14 out of the 92 patients (15.2%), and 8 of these (57.1%) were grade 3-4. Anti-cetuximab IgEs were detected in 7/8 of the patients (87.5%) with severe HSRs as compared with 14/78 patients (17.9%) with no HSR (p=0.0002). Predictive value of the anti-cetuximab IgE test for HSR events of grades 3-4 was calculated using Receiver Operating Characteristics analysis. With a cut-off value of 29 arbitrary units for the anti-cetuximab IgE, the ELISA test showed a sensitivity of 87.5%, specificity of 82.1%, positive predictive value of 33.3% and negative predictive value of 98.5%. Anti-cetuximab IgE ELISA detection could be a valuable tool to help the physician anticipate an anaphylaxis episode following cetuximab infusion and opt for a suitable alternative treatment.

Evolution of antinuclear antibodies and clinical patterns in patients with active rheumatoid arthritis with longterm infliximab therapy

OBJECTIVE

To investigate the effect of longterm infliximab therapy on serum levels of fluorescent antinuclear and anti-double and single-stranded DNA antibodies (FANA, anti-dsDNA, anti-ssDNA) in patients with rheumatoid arthritis (RA), and their possible association with clinical evolution.

METHODS

Sera from 58 RA patients, treated for one to 3 years with infliximab, were retrospectively analyzed. Matched control groups were RA patients treated with corticosteroids or methotrexate. FANA were tested using HEp-2 cells, and anti-dsDNA and anti-ssDNA IgG by ELISA. After 28 months of infliximab therapy, clinical status was evaluated in 43/58 patients with uninterrupted therapy and associations with autoantibody levels were investigated. Data were documented for patients who discontinued infliximab.

RESULTS

Over the 3 year period, significant increases in FANA and anti-ssDNA IgG levels were observed in infliximab treated patients (p < 0.001 and p < 0.01, respectively). In 43 patients with an uninterrupted infliximab regimen, association was found between high FANA (>or= 1/1280) and lower age (p = 0.048) and patient's assessment of infliximab's efficacy (p = 0.014). Three patients developed anti-dsDNA IgG, preceded by high anti-ssDNA IgG levels, and one of them developed a lupus-like syndrome. Neither the initial presence of high FANA levels nor their increase >or= 1/1280 was significantly associated with discontinuation of infliximab. In contrast, at baseline (p = 0.0012) and at the time of infliximab discontinuation (p = 0.0078), anti-ssDNA IgG (>or= 500 arbitrary units) were more frequent in 7 patients who stopped infliximab due to skin or systemic anaphylactoid reactions.

CONCLUSION

Monitoring of serum FANA, anti-dsDNA, and anti-ssDNA IgG antibodies provided predictors of lupus-like symptoms and/or anaphylactoid reactions in patients with RA.

Kinetics of spleen and Peyer's patch lymphocyte populations during gut parasite clearing in Cryptosporidium parvum infected suckling mice

Data from experimental and human cryptosporidiosis have established a major role of specific immunity in the control of Cryptosporidium parvum infection. In this work, alterations in spleen and Peyer's patch (Pp) lymphocytes were investigated in the course of a spontaneously resolutive gut cryptosporidiosis in four-day-old suckling NMRI mice infected with either 4 x 10(5) or 30 viable oocysts. Oocysts from entire small intestines, and spleen and Pp lymphocytes were examined using flow cytometry from day 7 to day 27 post-infection. Compared to uninfected animals, a 3-5 fold increase in the numbers of spleen TCR alphabeta+, CD4+, CD8+, TCR gammadelta+ and CD45R/B220+ lymphocytes was observed on day 17 post-infection in heavily infected animals. In Pp, more than ten-fold increases were observed, except for TCR gammadelta+ lymphocytes. At termination of infection, i.e. on days 21-23 after ingestion of 4 x 105 oocysts, T and B lymphocytes decreased rapidly in both organs, and remained lower than in uninfected animals on days 19-23 post-infection. In mice infected with 30 oocysts, similar alterations were observed in Pp, but not in spleen. Data suggest that in normally developing mice, clearance of gut C. parvum infection is associated with an initial increase in systemic and local lymphocyte numbers, followed by their decrease to below control levels during the recovery phase.