Lessons from Carl M. Pearson 1919 - 1981.

Carl M. Pearson was an energetic and exceptional physician-scholar-leader who founded, established, and broadened the Divisions of Rheumatology at University of California in Los Angeles (UCLA) beginning in 1956. His studies to induce myositis by injecting muscle saturated with the heat-killed tubercle bacillus, an emulsifier, and mineral oil (Freund's adjuvant) enabled his report that polyarthritis occurred with Freund's adjuvant alone in certain strains of rat and mice. This model of adjuvant arthritis allowed the next generation of studies to assess therapies for autoimmune diseases.

Safety and benefits of automated red cell depletion-exchange compared to standard exchange in patients with sickle cell disease undergoing chronic transfusion.

BACKGROUND: The Spectra Optia allows automated performance of red blood cell reduction and isovolemic hemodilution (IHD) prior to standard red cell exchange (RCE), and is primarily intended for patients with sickle cell disease (SCD) undergoing chronic RCE. Data on the safety of inducing transient further anemia and the benefits of IHD-RCE is limited and occasionally contradictory. STUDY DESIGN AND METHODS: In this retrospective crossover analysis of six patients with SCD who underwent chronic exchange with standard RCE (Cobe Spectra) followed by IHD-RCE (Spectra Optia), we compared safety and benefit outcomes with IHD-RCE vs standard RCE. RESULTS: There were statistically but not clinically significant drops in blood pressure in the post-IHD phase. With IHD-RCE, there were significant reductions in red blood cell (RBC) usage and/or lower fraction of cells and significant increases in postprocedure hematocrit (Hct) associated with increased preprocedure Hct. There were no differences achieved in the time interval between procedures or in the net RBC gain with IHD-RCE. Overall, there were also no significant differences in pre- and postprocedure percentage of hemoglobin S, reticulocyte count, interval daily hemoglobin A decrement, or postprocedure white blood cell, neutrophil, or platelet counts. CONCLUSIONS: Our study supports that IHD-RCE can be safely used in patients with stroke risk and compared to standard RCE, results in benefits of lower RBC usage and/or fraction of cells remaining and higher postprocedure Hct associated with higher preprocedure Hct. These findings support wider use of IHD-RCE, especially in the current environment with reduced availability of minority units.

Feasibility & safety of plasma exchange in paediatric neuro-immunology: A single center experience.

BACKGROUND: There is limited data available on the safety of therapeutic plasma exchange (TPE) for paediatric neuro-immunological disorders (PNID). In this study, we report our data on safety and feasibility of TPE for these disorders. METHODS: Retrospective chart review was performed to include all patient who received TPE for four major PNID conditions: autoimmune encephalitis (AIE), acute disseminated encephalomyelitis (ADEM), Neuromyelitis optic spectrum disorder (NMOSD) and transverse myelitis (TM). We recorded minor and major adverse effects (AEs) associated with each TPE procedure. Secondary analysis also looked at the efficacy data of TPE on these patients. RESULTS: Thirty-two patients with PNID received a total of 186 TPE cycles. Out of these, only 1 cycle (0.89%) in AIE subgroup, 1 (4.3%) in NMOSD and 1 (4.5%) in TM had adverse effects. No patients had major side effects. CONCLUSION: TPE was safe and well tolerated in our PNID patients.

Reversal of Severe Multiorgan Failure Associated With Sickle Cell Crisis Using Plasma Exchange: A Case Series.

OBJECTIVE: Red blood cell exchange (RBCE) is the standard of care for patients with sickle cell disease (SCD) who present with severe vaso-occlusive crisis (VOC). However, subsets of these critically ill patients have progressive multiorgan failure (MOF) despite RBCE therapy. The purpose of this case series is to describe the use of plasma exchange (PLEX) for the treatment of SCD-related MOF that is refractory to RBCE. METHODS: A retrospective case review of patients with severe MOF from sickle cell crisis unresponsive to RBCE who underwent PLEX in a 14-bed adult medical intensive care unit (ICU) at a tertiary care university hospital over a 4-year time period. Key laboratory data including complete blood count, indices of hemolysis, and markers of organ failure were recorded before and after both RBCE and PLEX. RESULTS: Our primary objective is to evaluate the effectiveness of PLEX, in addition to RBCE, on organ dysfunction, laboratory indices, and mortality. Of the 7 patients, 6 survived. Of the patients who survived, all remained hemodynamically stable during PLEX sessions and showed both clinical and laboratory evidences of improvement in hemolysis and organ function. Average time from completion of first PLEX treatment to initial laboratory signs of organ failure reversal for patients who survived was 15.6 hours, the average length of stay in the ICU was 5.6 days, and the average total length of stay in the hospital was 14 days. CONCLUSIONS: Plasma exchange, in addition to RBCE, may be a novel synergistic treatment option to decrease risk of mortality in patients with refractory VOC and MOF.

Targeting inflammatory pathways in axial spondyloarthritis.

The triggers and pathogenesis of axial spondyloarthritis (axSpA) are not yet completely understood. However, therapeutic agents targeting tumor necrosis factor-α and interleukin-17 inflammatory pathways have proven successful in suppressing many of the clinical symptoms and signs of axSpA, giving us an indication of which pathways are responsible for initiating and maintaining the inflammation. The mechanisms that eventuate in syndesmophytes and ankyloses are less clear. This review addresses these two critical pathways of inflammation, discussing their nature and these factors that may activate or enhance the pathways in patients with axSpA. In addition, genetic and other markers important to the inflammatory pathways implicated in axSpA are explored, and prognostic biomarkers are discussed. Treatment options available for the management of axSpA and their associated targets are highlighted.

Genetic and inflammatory factors associated with psoriatic arthritis: Relevance to diagnosis and management.

Psoriatic arthritis (PsA) is a heterogeneous chronic inflammatory musculoskeletal condition with complex pathophysiology. In recent years, understanding of the pathogenesis of PsA has improved substantially. Several genetic and inflammatory factors have been identified and studied as targets for new biologic disease-modifying therapies. This review presents findings from a detailed literature assessment conducted to identify genes and biomarkers associated with PsA and its most common comorbidities. This literature assessment identifies genes and biomarkers that may be predictive of the onset and severity of PsA, places them in the context of our understanding of PsA pathogenesis, and explores potential connections between the pathways involved in PsA and current biologic therapeutics used to treat PsA. Knowledge of the genetics and inflammatory factors associated with disease pathogenesis can support the targeted development of new biologic therapies and biomarkers for PsA.

Therapeutic plasma exchange for a case of refractory opsoclonus myoclonus ataxia syndrome.

Opsoclonus myoclonus ataxia syndrome (OMAS) can be refractory to standard therapies and devastating. Alternative treatments are imperative. A 14-month-old male diagnosed with neuroblastoma and paraneoplastic OMAS achieved complete cancer remission with chemotherapy. The OMAS, however, persisted over the subsequent 4 years despite numerous immune-modulatory and immunosuppressive therapies. The patient ultimately achieved complete remission following therapeutic plasma exchange (TPE) combined with rituximab and intravenous immunoglobulin. After three asymptomatic years, he relapsed. Upon reintroducing TPE and rituximab plus oral prednisolone, the patient rapidly achieved a second complete remission. This case offers proof-of-principle for the potential efficacy of TPE for neuroblastoma-associated OMAS.

Case series supporting heme detoxification via therapeutic plasma exchange in acute multiorgan failure syndrome resistant to red blood cell exchange in sickle cell disease.

BACKGROUND: Depletion of haptoglobin (Hp) and hemopexin (Hx) with increase in free hemoglobin and heme are important etiologies of vaso-occlusive complications in sickle cell disease (SCD). This study is the first to show an association between clinical improvement in SCD and repletion of Hp and Hx by therapeutic plasma exchange (TPE) using plasma replacement. STUDY DESIGN AND METHODS: Thirteen fresh-frozen plasma (FFP) units derived from consecutive whole blood donations were thawed at 37°C after 10 months of storage; Hp and Hx concentrations immediately postthaw and after 5 days of refrigerated storage were analyzed by enzyme-linked immunosorbent assay (ELISA). All SCD patients presenting to a single institution over a 2-year period with acute multiorgan failure syndrome resistant to red blood cell exchange (RCE) were treated with TPE with FFP replacement; concentrations of Hp, Hx, and heme were evaluated before and after TPE by ELISA. RESULTS: Plasma concentrations of Hp and Hx decreased approximately 20% (p ≤ 0.002) after 5 days of refrigerated storage. Significant mean fold increases after TPE of 10 for Hp (p < 0.005) and seven for Hx (p < 0.003) and a 30% mean decrease in heme concentrations (p = 0.07) were noted in association with clinical improvement (three patients), whereas minimal increases in Hp and Hx were associated with continued clinical deterioration in one patient. CONCLUSION: Fresh-frozen plasma rather than thawed plasma is optimal for Hp and Hx replacement. Patient data are consistent with Hp and Hx increases via TPE limiting clinical toxicity of worsened hemolysis associated with severe vaso-occlusive complications refractory to RCE in SCD.

Transfusion-transmitted babesiosis leading to severe hemolysis in two patients with sickle cell anemia.

The intracellular parasites Babesia microti and Babesia duncani can be transmitted by blood transfusion and cause severe life-threatening hemolytic anemia in high-risk patients, including those with sickle cell disease. The rarity of the diagnosis, as well as its similar clinical presentation to delayed hemolytic transfusion reaction, may lead to a delay in diagnosis, as well as inappropriate treatment with steroids or other immunosuppressive agents. The morbidity caused by this disease in especially vulnerable populations justifies the need for a universal blood-screening program in endemic areas.

Comprehensive appraisal of magnetic resonance imaging findings in sustained rheumatoid arthritis remission: a substudy.

OBJECTIVE: To evaluate the effect of sustained American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) Boolean remission on residual joint inflammation assessed by magnetic resonance imaging (MRI) and to secondarily evaluate other clinical definitions of remission, within an early seropositive rheumatoid arthritis (RA) cohort. METHODS: A subcohort of 118 RA patients was enrolled from patients who completed the 2-year, double-blind randomized Treatment of Early Aggressive Rheumatoid Arthritis (TEAR) trial. Patients received a single contrast-enhanced 1.5T MRI of their most involved wrist. Two readers scored MRIs for synovitis, osteitis, tenosynovitis, and erosions. Clinical assessments were performed every 3 months during the trial and at time of MRI. RESULTS: The subcohort was 92% seropositive with mean age 51 years, duration 4.1 months, and Disease Activity Score in 28 joints using the erythrocyte sedimentation rate 5.8 at TEAR entry. Total MRI inflammatory scores (tenosynovitis + synovitis + osteitis) were lower among patients in clinical remission. Lower MRI scores were correlated with longer duration of Clinical Disease Activity Index (CDAI) remission (ρ = 0.22, P = 0.03). At the time of MRI, 89 patients had no wrist pain/tenderness/swelling; however, all 118 patients had MRI evidence of residual joint inflammation after 2 years. No statistically significant differences in damage or MRI inflammatory scores were observed across treatment groups. CONCLUSION: This is the first detailed appraisal describing the relationship between clinical remission cut points and MRI inflammatory scores within an RA randomized controlled trial. The most stringent remission criteria (2011 ACR/EULAR and CDAI) best differentiate the total MRI inflammatory scores. These results document that 2 years of triple therapy or tumor necrosis factor plus methotrexate treatment in early RA does not eliminate MRI evidence of joint inflammation.

Comparative genomic profiling of synovium versus skin lesions in psoriatic arthritis.

OBJECTIVE: To our knowledge, there is no broad genomic analysis comparing skin and synovium in psoriatic arthritis (PsA). Also, there is little understanding of the relative levels of cytokines and chemokines in skin and synovium. The purpose of this study was to better define inflammatory pathways in paired lesional skin and affected synovial tissue in patients with PsA. METHODS: We conducted a comprehensive analysis of cytokine and chemokine activation and genes representative of the inflammatory processes in PsA. Paired PsA synovial tissue and skin samples were obtained from 12 patients on the same day. Gene expression studies were performed using Affymetrix HGU133 Plus 2.0 arrays. Confirmatory quantitative real-time polymerase chain reaction (PCR) was performed on selected transcripts. Cell populations were assessed by immunohistochemistry and immunofluorescence. RESULTS: Globally, gene expression in PsA synovium was more closely related to gene expression in PsA skin than to gene expression in synovium in other forms of arthritis. However, PsA gene expression patterns in skin and synovium were clearly distinct, showing a stronger interleukin-17 (IL-17) gene signature in skin than in synovium and more equivalent tumor necrosis factor (TNF) and interferon-γ gene signatures in both tissues. These results were confirmed with real-time PCR. CONCLUSION: This is the first comprehensive molecular comparison of paired lesional skin and affected synovial tissue samples in PsA. Our results support clinical trial data showing that PsA skin and joint disease are similarly responsive to TNF antagonists, while IL-17 antagonists have better results in PsA skin than in PsA joints. Genes selectively expressed in PsA synovium might direct future therapies for PsA.

Different tumor necrosis factor α antagonists have different effects on host susceptibility to disseminated and oropharyngeal candidiasis in mice.

Tumor necrosis factor α is important for the host defense against intracellular pathogens. We tested the effect of mouse analogs of human TNF-α antagonists, the rat anti-mouse TNF-α monoclonal antibody (XT22) and the soluble mouse 75 kDa TNF-α receptor fused to the Fc portion of mouse IgG1 (p75-Fc), on the susceptibility of mice to hematogenously disseminated candidiasis (HDC) and oropharyngeal candidiasis (OPC). Both XT22 and p75-Fc significantly reduced mice survival, increased kidney fungal burden, and reduced leukocyte recruitment during HDC. However, only XT22 significantly increased the oral fungal burden and reduced leukocyte recruitment during OPC. This result suggests that XT22 and p75-Fc affect host susceptibility to different types of Candida albicans infections by different inhibitory mechanisms.

Team-based learning in a pathology residency training program.

OBJECTIVES: Team-based learning (TBL) has been integrated into undergraduate and medical education curricula in many institutions. However, TBL has not been widely introduced into postgraduate medical education. Our study aimed to measure the effect of TBL on promoting learning and teamwork in the setting of pathology residency training. METHODS: Four TBL sessions were held and individual and group readiness assurance tests (IRAT/GRATs) were performed; scores were compared using Wilcoxon matched-pairs signed rank tests. Residents completed 18-item validated team performance surveys measuring the quality of team interactions on a scale of 0 (none of the time) to 6 (all of the time). Mean and standard deviation were calculated for each item. RESULTS: Scores on the IRAT vs GRAT were significantly different (P < .05). The team performance survey received mean scores ranging from 5.3 ± 1.1 to 6.0 ± 0.0. CONCLUSIONS: The use of TBL promotes teamwork and learning in a pathology residency program. Residents scored higher on the readiness assurance tests when working in teams, demonstrating the effectiveness of team learning and achievement. In addition, the Accreditation Council for Graduate Medical Education competencies of professionalism and interpersonal and communication skills were further enhanced by incorporating TBL into pathology residency training.

Significance of sex in achieving sustained remission in the consortium of rheumatology researchers of North America cohort of rheumatoid arthritis patients.

OBJECTIVE: To determine whether men with rheumatoid arthritis (RA) are more likely to achieve remission compared to women. METHODS: RA patients enrolled in the Consortium of Rheumatology Researchers of North America (CORRONA) cohort between October 2001 and January 2010 were selected for the present analyses. Detailed clinical, demographic, and drug utilization data were available at enrollment (baseline) and at subsequent followup visits. We examined the influence of sex on the Clinical Disease Activity Index remission score (≤2.8) using sustained remission or point remission as the primary outcome measure in multivariate stepwise logistic regression models. We stratified the data by RA duration at baseline (≤2 years or >2 years) to investigate whether RA duration had differential effects on remission in men and women. RESULTS: A total of 10,299 RA patients (2,406 men and 7,893 women) were available for this study. In both early and established RA, women had more severe disease at baseline with worse disease activity measures, modified Health Assessment Questionnaire disability index score, pain on a visual analog scale, and depression. Women were also more likely to have been treated with disease-modifying antirheumatic drugs and anti-tumor necrosis factor therapy compared to men. In the regression models, male sex was associated with sustained remission in early RA (odds ratio [OR] 1.38, 95% confidence interval [95% CI] 1.07-1.78, P = 0.01), but not in established RA. However, for point remission, an inverse association was observed with male sex in established RA (OR 0.65, 95% CI 0.48-0.87, P = 0.005) and not in early RA. CONCLUSION: Within the large real-life CORRONA cohort of RA patients, men were more likely to achieve sustained remission compared to women in early RA, although not in established RA.

Gender and ethnicity differences in patients with diffuse systemic sclerosis--analysis from three large randomized clinical trials.

OBJECTIVE: Although the incidence of dcSSc is higher in African-American and Hispanic populations compared with European Caucasian patients, it is not clear whether there are differences in subsequent disease course. Also, the potential impact of gender on the disease course of dcSSc is not well defined. Our objective was to assess the course of modified Rodnan skin score (MRSS), HAQ-disability index (HAQ-DI) and forced vital capacity per cent (FVC%) predicted between men vs women and three ethnic groups with dcSSc participating in three randomized clinical trials (RCTs). METHOD: Data from RCTs (n = 495) were pooled and analysed. Baseline characteristics were compared in men vs women and among ethnic groups. A linear mixed effects model was used to assess the predictors of MRSS, HAQ-DI and FVC%. The primary independent variables were time-in-study and its interaction with gender and ethnicity. The models were adjusted for other covariates that were significant at baseline between gender and ethnicity analyses. RESULTS: Men had lower HAQI-DI scores compared with women (P < 0.05). Among the three ethnic groups, Caucasians were older, African-Americans had lower FVC% predicted and Hispanics had greater tender joint counts (P < 0.05). The course of MRSS, HAQ-DI and FVC% predicted during the study period was not significantly different between gender and three ethnicities. Time-in-study was an independent predictor of improvement in MRSS and HAQ-DI. CONCLUSION: Our analysis explores the influence of gender and ethnicity on disease course in RCTs. These findings are relevant to issues of future trial design.

The utility of MRI in predicting radiographic erosions in the metatarsophalangeal joints of the rheumatoid foot: a prospective longitudinal cohort study.

INTRODUCTION: Magnetic resonance imaging (MRI) may reveal rheumatoid arthritis (RA) changes in the feet when hands are normal. The purpose of this study was to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a metatarsophalangeal (MTP) erosion on MRI to predict a subsequent radiographic erosion in the same joint. Similar analyses were performed for bone marrow edema, predicting a subsequent MRI erosion. Descriptive results of other lesions are reported. METHODS: Fifty patients with RA of less than 5 years' duration who were rheumatoid factor-positive and/or anti-cyclic citrullinated peptide-positive were recruited. Patients on anti-tumor necrosis factor (TNF) therapy were excluded. Anti-TNF therapy could begin after enrollment. MRI and radiographs of the 3rd, 4th, and 5th MTP joints bilaterally were taken at baseline and at 6, 12, and 24 months. Clinical data were collected. RESULTS: Fifty patients were recruited; 46 patients had suitable data. Results for MRI erosions predicting subsequent radiographic erosions for 6, 12, and 24 months, respectively, were as follows: sensitivity 0.75, 0.60, 0.75; specificity 0.93, 0.94, 0.94; PPV 0.086, 0.10, 0.17; NPV 0.998, 0.995, 0.995. Results for MRI bone marrow edema predicting MRI erosions at 6 and 12 months, respectively, revealed sensitivity 0.50, 0.67; specificity 0.97, 0.97; PPV 0.25, 0.50; NPV 0.99, 0.99. Synovitis was the most common finding and, when present in isolation, resolved on 67.3% of subsequent studies. MRI erosions persisted on subsequent studies with one exception. Forty-six percent of the cohort was on anti-TNF therapy after study inception. CONCLUSIONS: The PPV of MRI erosions to predict subsequent radiographic erosions was low. Similarly, the PPV of bone marrow edema to predict a later MRI erosion was low. Alternatively, the NPV of the absence of an MRI erosion or bone marrow edema predicts that a later radiographic erosion or MRI erosion will likely not develop. Anti-TNF therapies may have resulted in the lower-than-anticipated PPVs. MRI descriptions of bone edema may represent a more critical time to treat in order to avoid damage, whereas an MRI erosion represents more permanent damage. This study suggests that imaging modalities more sensitive than radiographs are necessary to monitor disease in the biologic era.

Differences in binding and effector functions between classes of TNF antagonists.

There are currently two Food and Drug Administration-approved classes of biologic agents that target tumor necrosis factor-alpha (TNF-alpha): anti-TNF monoclonal antibodies (mAbs) (adalimumab and infliximab), and soluble TNF receptors (etanercept). This study examined the ability of the TNF antagonists to: (1) bind various polymorphic variants of cell surface-expressed Fc receptors (FcgammaRs) and the complement component C1q, and (2) mediate Ab-dependent cellular cytotoxicity (ADCC) and complement-mediated cytotoxicity (CDC) killing of cells expressing membrane-bound TNF (mTNF) in vitro. Both mAbs and the soluble TNF receptor demonstrated low-level binding to the activating receptors FcgammaRI, FcgammaRIIa, and FcgammaRIIIa, and the inhibitory receptor FcgammaRIIb, in the absence of exogenous TNF. However, upon addition of TNF, the mAbs, but not etanercept, showed significantly increased binding, in particular to the FcgammaRII and FcgammaRIII receptors. Infliximab and adalimumab induced ADCC much more potently than etanercept. In the presence of TNF, both mAbs bound C1q in in vitro assays, but etanercept did not bind C1q under any conditions. Infliximab and adalimumab also induced CDC in cells expressing mTNF more potently than etanercept. Differences in the ability to bind ligand and mediate cell death may account for the differences in efficacy and safety of TNF antagonists.

Efficacy and safety of etanercept 50 mg twice a week in patients with rheumatoid arthritis who had a suboptimal response to etanercept 50 mg once a week: results of a multicenter, randomized, double-blind, active drug-controlled study.

OBJECTIVE: To evaluate the efficacy and safety of treatment with 50 mg of etanercept twice a week plus weekly methotrexate (MTX; > or =15 mg) in patients with rheumatoid arthritis (RA) who had a suboptimal response to 50 mg of etanercept once a week plus weekly MTX (> or =15 mg). METHODS: In this multicenter, randomized, double-blind, active drug-controlled study, suboptimal responders to treatment with MTX plus etanercept 50 mg once weekly were given MTX plus etanercept 50 mg twice weekly (n = 160) or MTX plus etanercept 50 mg once weekly plus a placebo (n = 40) for 12 weeks. In a subsequent 12-week open-label period, patients who responded to etanercept 50 mg twice weekly decreased their dosage to 50 mg once weekly, those who had a partial response to etanercept 50 mg once weekly increased their dosage to 50 mg twice weekly, and those who had no response to etanercept 50 mg twice weekly were discontinued. The primary end point was the proportion of patients with a response on the Disease Activity Score 28-joint assessment (DAS28) at week 12. RESULTS: A total of 201 patients were randomized; 187 completed 12 weeks, and 102 completed 24 weeks. At week 12 (double-blind period), the DAS28 response in the 50 mg twice weekly and the 50 mg once weekly groups was not significantly different (45.6% versus 35.0%; P = 0.285), and similar proportions of patients in the groups taking 100 mg and 50 mg experienced adverse events (34.4% versus 37.5%; P = 0.711). Serious adverse events occurred in 7 of 160 of the 50 mg twice weekly group and 0 of 40 of the 50 mg once weekly group (P = 0.387), and serious infectious events occurred in 3 of 160 patients in the 50 mg twice weekly group (P = 0.884). CONCLUSION: Etanercept 50 mg once weekly is an optimal dosage in most patients with RA. Increasing the dosage from 50 mg once weekly to 50 mg twice weekly in suboptimal responders did not significantly improve their DAS28 responses.

Binding characteristics of tumor necrosis factor receptor-Fc fusion proteins vs anti-tumor necrosis factor mAbs.

Tumor necrosis factor (TNF) antagonists are efficacious in the treatment of various autoimmune diseases. Two classes of TNF antagonists are currently commercially available: soluble TNF receptor-Fc fusion proteins (etanercept) and anti-TNF mAbs (adalimumab and infliximab). The classes differ in molecular structures and mechanisms of action. The interactions between TNF antagonists with TNF molecules were characterized. The anti-TNF mAbs, but not the soluble TNF receptor, formed visible lines of precipitation in Ouchterlony assays. The molecular weights of complexes formed by TNF (52 kDa) with either etanercept (130 kDa), adalimumab (150 kDa), or infliximab (average 165 kDa) were determined by size exclusion chromatography-light-scattering assays. Etanercept and TNF formed complexes of 180 and 300 kDa, representing one and two etanercept monomers bound to a TNF trimer, respectively. Adalimumab and infliximab formed a variety of complexes with TNF with molecular weights as high as 4,000 and 14,000 kDa, respectively, suggesting the presence of complexes with a wide range of sizes and stoichiometries. The absence of large complex formation with the binding of soluble receptor-fusion proteins to TNF may account for the different clinical efficacy and safety profiles of the two classes of TNF antagonists.

Structural-functional relationships of TNF-alpha antagonists: next steps.

The balance between effective tumor necrosis factor (TNF) blockade to control aggressive autoimmune disease states and adequate remaining TNF activity to confer immunoprotection against infections such as tuberculosis is an important and complex issue. An increased scientific understanding of how each of the TNF antagonist agents affects the complex interactions of the inflammation cascade and apoptosis, and whether the effects are modulatory or destructive, is needed. The data presented in this supplement highlight the need for further research into these key areas, and illustrate our current understanding of the mode of action of TNF blockers as only the tip of the iceberg.