Helgi Valdimarsson

Low Serum Mannose-Binding Lectin Level Increases the Risk of Death due to Pneumococcal Infection

Abstract Background. Previous studies have shown associations between low mannose-binding lectin (MBL) level or variant MBL2 genotype and sepsis susceptibility. However, MBL deficiency has not been rigorously defined, and associations with sepsis outcomes have not been subjected to multivariable analysis. Methods. We reanalyzed MBL results in a large cohort with use of individual data from 4 studies involving a total of 1642 healthy control subjects and systematically defined a reliable deficiency cutoff. Subsequently, data were reassessed to extend previous MBL and sepsis associations, with adjustment for known outcome predictors. We reanalyzed individual data from 675 patients from 5 adult studies and 1 pediatric study of MBL and severe bacterial infection. Results. XA/O and O/O MBL2 genotypes had the lowest median MBL concentrations. Receiver operating characteristic analysis revealed that an MBL cutoff value of 0.5 ≪g/mL was a reliable predictor of low-producing MBL2 genotypes (sensitivity, 82%; specificity, 82%; negative predictive value, 98%). MBL deficiency was associated with increased likelihood of death among patients with severe bacterial infection (odds ratio, 2.11; 95% confidence interval, 1.30–3.43). In intensive care unit–based studies, there was a trend toward increased risk of death among MBL-deficient patients (odds ratio, 1.58; 95% confidence interval, 0.90–2.77) after adjustment for Acute Physiology and Chronic Health Enquiry II score. The risk of death was increased among MBL-deficient patients with Streptococcus pneumoniae infection (odds ratio, 5.62; 95% confidence interval, 1.27–24.92) after adjustment for bacteremia, comorbidities, and age. Conclusions. We defined a serum level for MBL deficiency that can be used with confidence in future studies of MBL disease associations. The risk of death was increased among MBL-deficient patients with severe pneumococcal infection, highlighting the pathogenic significance of this innate immune defence protein.

Mannan binding lectin as an adjunct to risk assessment for myocardial infarction in individuals with enhanced risk

Inflammation can predispose to myocardial infarction (MI), and mannan binding lectin (MBL) promotes phagocytic clearance of inflammatory agents, but the predictive value of MBL levels for MI is not known. MBL was analyzed in subgroups of the population-based Reykjavik study, a cohort of 19,381 participants recruited from 1967. MBL levels were very stable over time (self correlation: 0.86). In a cross-sectional group from the original cohort (n = 987), high MBL (>1,000 μg/L) was associated with a greatly lowered odds ratio for MI (0.64, P < 0.001). To verify this finding, a nested case control sample (n = 1,309) was randomly selected from the cohort. High MBL at recruitment was also associated with decreased MI risk in this follow-up group, but to a lesser extent and not significant for the whole group, smokers, or hypertensive individuals. However, high MBL was as in the cross-sectional group, associated with greatly decreased MI risk in diabetic (P = 0.02) or hypercholesterolemic individuals (P = 0.004). This also applied to raised erythrocyte sedimentation rate (P = 0.007). Diabetic patients with high MBL did not have a higher MI risk than nondiabetic individuals. Our findings indicate that high MBL may predict decreased likelihood of MI, particularly in diabetics, and are consistent with the possibility that MBL may promote clearance of atherogenic agents.

Effect of rheumatoid factor on mortality and coronary heart disease

Objective An association between rheumatoid factor (RF) and increased mortality has been described in individuals with rheumatoid arthritis. The objective of this study was to determine the effect of RF on mortality and coronary heart disease (CHD) in the general population. Methods Subjects were participants in a population-based study focused on cardiovascular disease who attended for a study visit during the years 1974–84. RF was measured and information obtained on cardiovascular risk factors, joint symptoms and erythrocyte sedimentation rate (ESR). The subjects were followed with respect to mortality and incident CHD through 2005. Adjusted comparison of overall survival and CHD event-free survival in RF-positive versus RF-negative subjects was performed using Cox proportional hazards regression models. Results Of 11 872 subjects, 140 had positive RF. At baseline RF was associated with diabetes mellitus and smoking and inversely associated with serum cholesterol. RF-positive subjects had increased all-cause mortality (HR 1.47, 95% CI 1.19 to 1.80) and cardiovascular mortality (HR 1.57, 95% CI 1.15 to 2.14) after adjusting for age and sex. Further adjustment for cardiovascular risk factors and ESR only modestly attenuated this effect. An increase in CHD among the RF-positive subjects did not reach statistical significance (HR 1.32, 95% CI 0.96 to 1.81, adjusted for age and sex). Subjects with RF but without joint symptoms also had increased overall mortality and cardiovascular mortality (HR for overall mortality 1.33, 95% CI 1.01 to 1.74, after adjustment). Conclusion In a general population cohort, RF was associated with increased all-cause mortality and cardiovascular mortality after adjustment for cardiovascular risk factors, even in subjects without joint symptoms.

A prospective study on the incidence of rheumatoid arthritis among people with persistent increase of rheumatoid factor

OBJECTIVES To study the stability of rheumatoid factor (RF) increases and to compare the incidence of rheumatoid arthritis (RA) in people with transient or persistent increase of one or more RF isotypes. METHODS From an original cohort of nearly 14 000 participants in a population study, 135 previously RF positive persons were recruited in 1996 and evaluated according to the 1987 ACR criteria. The observation time ranged from 9–22 years (mean 16.5). Blood samples were obtained from all participants at entry and again in 1996. RESULTS About 40% of the participants who had only one raised RF isotype in the original sample had become RF negative in 1996 compared with only 15% of those with increase of two or three RF isotypes (p=0.002). The seven participants who developed RA during the study period all had persistently raised RF. Six of the 54 participants with more than one RF isotype raised in 1996 developed RA, corresponding to an annual incidence of 0.67%, which was 7.5 times higher than observed in the other participants (p=0.045). CONCLUSION Symptom free persons with persistently raised RF have greatly increased risk of developing RA. This suggests that dysregulation of RF production is a predisposing factor in RA.

Does smoking stimulate rheumatoid factor production in non-rheumatic individuals ?

Smoking has been associated with increased incidence of rheumatoid arthritis (RA), joint damage and positive rheumatoid factor (RF). Here we report an analysis of the association between smoking and IgM, IgG and IgA RF in a cohort of non‐rheumatic individuals participating in a prospective longitudinal study of the incidence and significance of elevated RF. From the initial cohort of nearly 14,000 randomly selected individuals aged 52–80 years, 109 RF‐positive and 187 RF‐negative non‐rheumatic participants were recruited. All participants were tested for RF at least twice at an interval ranging from 4 to 13 years. Of the RF‐negative participants 21.9% were active smokers compared to 34.1% of IgM RF‐positive (p=0.035), 20.8% of IgG RF‐positive (N.S.) and 34.4% of IgA RF‐positive participants (p=0.047). Smoking was most prevalent (44.8%) amongst participants with elevation of both IgM and IgA RF (p=0.008), and smokers were also significantly more likely to have a persistent elevation of RF than non‐smokers (p=0.024). These findings indicate that smoking may influence the immune system, leading to increased production of IgM and IgA RF.

Raised IgA Rheumatoid Factor (RF) but not IgM RF or IgG RF is Associated with Extra-articular Manifestations in Rheumatoid Arthritis

In rheumatoid arthritis (RA) seropositivity has been associated with poor prognosis including bone erosions and extra-articular manifestations. However, findings have been conflicting on the association between individual rheumatoid factor (RF) isotypes and extra-articular manifestations. In this study the occurrence of extra-articular manifestations was examined in the context of the RF isotype patterns rather than individual RF isotypes. IgM, IgG and IgA RF was measured by ELISA in 74 patients with RA and the findings correlated with the presence or absence of extra-articular manifestations. Of the IgA RF positive patients 80% had one or more extra-articular manifestations. In contrast, only 21% of patients with raised IgM and/or IgG RF but normal IgA RF had some extra-articular manifestations and 27% of the seronegative patients. It is concluded that the previously reported association between raised RF and extra-articular manifestations in RA can largely be attributed to the IgA RF isotype.

Cyclosporin A in psoriatic arthritis: an open study.

Eight patients with psoriatic arthritis entered an open study to determine the efficacy of oral cyclosporin A for their treatment. The starting dose was 3.5 mg/kg daily. Findings after the first six months are reported. One patient withdrew from the study after five months because of tremors, general malaise, and lack of improvement. Seven patients continued through the study, and marked improvement was found after two months in all clinical indices. The skin lesions improved in a parallel fashion. The cyclosporin A dose had to be reduced temporarily by 25% in three patients because of an increase in serum creatinine of more than 50%. A rise in diastolic blood pressure in three patients responded to treatment. The study suggests that cyclosporin A effectively treats arthritic manifestations of psoriasis as well as psoriatic skin lesions.

Reciprocal Changes in Complement Activity and Immune-Complex Levels during Plasma Infusion in a C2-Deficient SLE Patient

Although systemic lupus erythematosus (SLE) is abnormally common in individuals with complement deficiency, conclusive evidence has been lacking for a direct causal relationship between disease manifestations and a missing complement component. A patient with C2 deficiency and SLE has been treated with 56 courses of fresh frozen plasma (FFP) infusions over a period of 8 years. Each infusion, involving a total of 12 units of FFP administered in equal doses over 4 consecutive days, has consistently resulted in a transient restoration of the classical pathway of complement, and a full clinical remission lasting 6-8 weeks. This report is concerned with changes in the levels of immune complexes, C2 and C3d during an infusion cycle. Four progressively rising peaks in C2 and C3d were observed during the 4 days of the plasma infusion, and these peaks coincided with four reciprocally descending troughs in the levels of immune complexes. Identical fluctuations have been consistent in all the plasma-infusion cycles that have so far been monitored, and their consistent association with clinical remissions indicates a causal relationship between the C2 restoration and clinical remissons in this C2-deficient SLE patient.

Deficiency of complement-dependent prevention of immune precipitation in systemic sclerosis

Background: Previous studies have indicated that complement may be activated or inherently abnormal in systemic sclerosis (SSc), and it has been suggested that immune complex deposition plays a part in the microvascular damage of this disease. Objective: To study several aspects of the complement system in 24 patients with SSc. Methods: Complement dependent prevention of immune precipitation (PIP) was measured by a sensitive enzyme immunoassay, levels of C1q, C4, and C3 by rocket immunoelectrophoresis, C4 allotypes by high voltage agarose electrophoresis, and C4A, C4B, and C3d by an enzyme linked immunosorbent assay (ELISA). Results: PIP was markedly decreased in the patients with SSc (p<0.001). Abnormal complement activation was detected in nine patients as raised levels of the complement split product C3d. However, a relation between low PIP and complement activation was not seen. PIP was significantly lower in patients who carried the C4A*Q0 allotype (p=0.03), and a strong correlation was found between PIP and C4A concentration (p<0.00001). The PIP defect may, at least in some patients, be associated with the initial phase of the disease. Conclusions: The results show a previously unrecognised functional defect of complement in SSc; the defect correlates with low levels of classical pathway components and, in particular, C4A.

Elevation of only one rheumatoid factor isotype is not associated with increased prevalence of rheumatoid arthritis--a population based study.

Objective: To analyse the relationship between different rheumatoid factor (RF) isotype patterns and the prevalence of RA. Methods: Serum samples, collected between 1973 and 1983 from nearly 14000 randomly selected individuals, were screened for elevation of RF. In 1987, 173 RF positive and 156 matched RF negative participants were evaluated clinically. Results: Participants with elevation of only one RF isotype, most commonly IgM, did not have significantly higher prevalence of RA than the RF negative controls. Of the 17 RF positive individuals who were diagnosed with RA, 14 (82%) had a combined elevation of IgM and IgA RF. Conclusion: In contrast to a combined elevation of IgM and IgA RF, elevation of only one RF isotype may not be a significant risk factor for the development of RA.OBJECTIVE To analyse the relationship between different rheumatoid factor (RF) isotype patterns and the prevalence of RA. METHODS Serum samples, collected between 1973 and 1983 from nearly 14,000 randomly selected individuals, were screened for elevation of RF. In 1987, 173 RF positive and 156 matched RF negative participants were evaluated clinically. RESULTS Participants with elevation of only one RF isotype, most commonly IgM, did not have significantly higher prevalence of RA than the RF negative controls. Of the 17 RF positive individuals who were diagnosed with RA, 14 (82%) had a combined elevation of IgM and IgA RF. CONCLUSION In contrast to a combined elevation of IgM and IgA RF, elevation of only one RF isotype may not be a significant risk factor for the development of RA.