PubMed Health⌕ Search

Biomedical subjects

T Jónsson

Publications and source records attributed to T Jónsson.

31 records · Page 2Linked to original sources
PubMed1995

Clinical implications of IgA rheumatoid factor subclasses.

OBJECTIVES: To evaluate the diagnostic and pathogenetic significance of IgA rheumatoid factor (RF) subclasses in rheumatoid arthritis (RA). METHODS: Rheumatoid factors of the IgA class and IgA1 and IgA2 subclasses were measured by enzyme linked immunosorbent assay in 58 patients with RA, 31 patients with other rheumatic diseases, 30 non-rheumatic individuals with increased concentrations of IgA RF, and in 100 randomly selected healthy controls. RESULTS: Using a 95% cut off for the controls, 55% of the RA patients had increased total IgA RF, 64% IgA1 RF, and 60% IgA2 RF. RA patients with extraarticular manifestations more often had increased concentrations of IgA RF and both subclasses than patients without such manifestations (p < or = 0.01). Nearly all (31/32) RA patients with increased IgA RF had increases in both IgA RF subclasses, compared with 67% (20/30 of nonrheumatic symptom free individuals with increased IgA RF (p = 0.002). CONCLUSION: Increased concentrations of the IgA2 RF subclass appears to be more specific for RA than increased IgA1 RF. Measurement of IgA RF subclasses may be clinically useful.

Arthritis, Rheumatoid↗
PubMed1995

Selective increase of IgA rheumatoid factor in patients with gluten sensitivity.

An increased prevalence of raised autoantibodies, including rheumatoid factor, has been reported in patients with gluten sensitivity. However, rheumatoid factor has only been measured in small groups of patients and the findings have been conflicting. In this study IgM, IgG and IgA rheumatoid factor was measured in 89 patients with dermatitis herpetiformis and 22 patients with coeliac disease and compared with 89 normal controls. There was an increased prevalence of elevated IgA rheumatoid factor in the patients with dermatitis herpetiformis (13.5%; p = 0.036) and coeliac disease (18.2%; p = 0.078), while no such increase was found for the IgM or IgG rheumatoid factor isotypes. This selective increase of IgA rheumatoid factor suggests that rheumatoid factor production in patients with gluten sensitivity primarily results from immunological activation in the gut mucosa.

Adult↗
PubMed1995

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.

Adult↗
PubMed1992

Rheumatoid factor isotypes and cancer prognosis.

The relationship between rheumatoid factor (RF) and cancer was studied during a long-term health survey done in the Reykjavik area of Iceland since 1967. A total of 16,299 blood samples from 13,858 persons attending this health survey between 1974 and 1983 were screened for the presence of RF. In 1987, RF-positive participants in this study (n = 270) and matched RF-negative control subjects (n = 223) were evaluated for incidence and prognosis of cancer with information obtained from the comprehensive Icelandic Cancer Registry. The average observation time for this cohort was 9.3 years. Participants with raised immunoglobulin A RF in their original blood sample showed an increased risk of having cancer compared with both other members of the cohort and the national cancer incidence. Their total mortality was also higher during the study period. By contrast, patients with cancer and elevated immunoglobulin M RF before the diagnosis of cancer were more likely to survive than those who were immunoglobulin M RF negative. Cancer incidence in the RF-negative control group was not different from the expected national incidence of cancer in Iceland for that age group. It is suggested that elevation of immunoglobulin A RF is an adverse phenomenon in relation to cancer; elevation of immunoglobulin M RF is associated with a favorable prognosis.

Agglutination Tests↗
PubMed1992

Clinical significance of rheumatoid factor isotypes in seropositive arthritis.

In this cross-sectional study a comparison was made of rheumatoid factor (RF) isotypes in 203 RF positive patients with arthritis. Of these, 129 had rheumatoid arthritis (RA) and 74 a milder disease that would formerly have been classified as probable RA. The majority (74%) of the RA patients had elevations of two or three RF isotypes compared with only 34% of the patients with the milder form of arthritis. A striking feature was that combined elevation of IgM RF and IgA RF was found in 67% of the RA patients compared to only 20% of the patients with milder arthritis who most frequently had an isolated elevation of IgM RF (41%). RA patients with an isolated elevation of IgA RF were younger and had a shorter disease history than RA patients with an isolated elevation in IgM RF or a combined elevation of IgA RF and IgM RF. The prevalence of raised IgM RF was, furthermore, found to increase with age and disease duration. We conclude that a raised level of IgA RF is an adverse phenomenon in patients with seropositive arthritis while patients with an isolated increase in IgM RF may be expected to experience a relatively mild disease course.

Adolescent↗
PubMed1992

Population study of the importance of rheumatoid factor isotypes in adults.

Blood samples collected from 13,858 randomly selected subjects participating in a health survey in Iceland from 1974 to 1983 were tested for rheumatoid factor. Samples that were positive in a sensitive RF screening test were analysed further by the Rose-Waaler technique and an isotype specific enzyme linked immunosorbent assay (ELISA). In 1987 the 173 available participants who were RF positive and 156 matched RF negative controls were evaluated clinically for rheumatoid diseases. RF levels and isotype patterns were more persistent in the patients with rheumatoid arthritis (RA) than in RF positive subjects who did not have overt RA. The prevalence of RA was only 19% in the participants who were RF positive in 1987. Forty per cent of the participants who had a persistent (four to 13 years) increase of IgA RF combined with either IgM or IgG RF were diagnosed as having RA. A positive correlation was found between RF levels and various manifestations of RA. This association was stronger for the IgA and IgG RF isotypes than for IgM RF. Excluding RF positivity as a diagnostic parameter, RA was diagnosed in 33 of the participants and 20 (61%) of these patients had increased levels of IgM and IgA RF. Patients with RA with bone erosions in their hands had higher levels of IgA RF than patients without erosions, but an association was not found between bone erosions and other RF isotypes. None of the RF negative participants who were symptom free when the original blood sample was taken developed RA during the four to 13 year follow up period. In contrast, five symptom free RF positive participants developed RA during this period. These five patients had all had increased levels of at least two RF isotypes before the onset of their symptoms. It is concluded that the IgA and IgG RF isotypes have a closer association with the clinical parameters of RA than IgM RF. Furthermore, increases in RF can precede clinical manifestations of RA and this applies in particular to the IgA and IgG RF isotypes.

Adult↗
PubMed1992

Disease manifestations in patients with isolated elevation of IgA rheumatoid factor.

In this retrospective study a comparison was made between the disease manifestations in patients with isolated elevation of IgA rheumatoid factor (RF) and patients with elevation of IgM RF. Of the 28 patients with isolated elevation of IgA RF, 14 (50%) had rheumatoid arthritis (RA) and 9 (32%) miscellaneous other inflammatory rheumatic disorders. It was found that 61% of these 23 rheumatic patients had disease manifestations from mucous membranes or secretory organs compared to 18% in the IgM RF positive group (p = 0.020). Patients with RA and an isolated elevation of IgA RF had more often mucosal or secretory symptoms than RA patients with elevation of IgM RF. We suggest that IgA RF may be a marker for activation of the mucosal or secretory immune system. The relationship between IgA RF and non-articular symptoms is discussed.

Arthritis, Rheumatoid↗
PubMed1989

Bronchopulmonary carcinoids in Iceland 1955-1984. A retrospective clinical and histopathologic study.

Twenty-two cases of bronchopulmonary carcinoid tumor diagnosed in Iceland in the 30-year period 1955-1984 were analyzed. Carcinoid comprised 2% of all primary lung tumors registered in that period. The crude incidence was 0.36 cases/100,000 population/year. The patients' mean age was 48 years and 68% were female. The most common presenting symptom was recurrent pneumonia; only three patients had hemoptysis. One patient had carcinoid syndrome. Two of the 22 tumors were peripheral. Tumor size was 0.8-9 cm, mean 2.8 cm. Of the resectable bronchial tumors, 80% had invaded the pulmonary parenchyma and 18% had metastasized to lymph nodes. Four carcinoid tumors were atypical and showed more malignant behavior. One of them was originally diagnosed as oat-cell carcinoma. Sixteen patients with resectable carcinoid tumor were alive 3 1/2 to 29 years after removal of the tumor.

Adolescent↗
PubMed1989

Carcinoid tumors of the appendix in children younger than 16 years. A retrospective clinical and pathologic study.

Eighteen cases of appendiceal carcinoid in children aged 4 to 15 years, 14 of them girls, are reviewed. Most (73%) of the tumors were located in the distal third of the appendix. Tumor size, measured in histologic sections, ranged from 0.1 to 1.2 cm. In three cases the tumor had invaded the mesoappendix. No metastases were found. Standard appendectomy was performed in all cases as the only surgical procedure. The preoperative clinical diagnosis in 15 cases was acute appendicitis, which was histologically confirmed in 53%. At follow-up 2.2 to 29.3 years postoperatively (mean 16.4 years), all the patients were alive and without suspected or verified recurrence of carcinoid.

Adolescent↗
PubMed1987

Relation between bone erosions and rheumatoid factor isotypes.

Total rheumatoid factor (RF) activity and individual RF isotypes were measured in 62 patients with rheumatic diseases. Retrospective analysis of available x rays showed an association between IgA RF and the occurrence of periarticular bone erosions in hands. In contrast, IgG RF and IgM RF did not show any significant association with erosions. Furthermore, a close correlation was observed between the RF isotype levels in simultaneously drawn serum and synovial fluid samples. The possible significance of IgA RF in the pathogenesis of bone erosions is discussed.

Adolescent↗