Antikeratin antibodies in serum and synovial fluid show specificity for rheumatoid arthritis in a study of connective tissue diseases.

Tests for antikeratin antibodies (AKA) were performed on 2152 disease-associated and control sera by indirect immunofluorescence (IF) on rat oesophagus substrate. The incidence of AKA was significantly raised in rheumatoid arthritis (37%) in comparison with systemic sclerosis (8%), psoriasis (7%), ankylosing spondylitis (6%), systemic lupus erythematosus (3%), and normal controls (2%). AKA were detected in synovial fluid obtained from patients with rheumatoid arthritis (RA) (48%) but not from patients with other conditions. Further experiments on AKA-positive sera showed reactivity with stratum corneum of rabbit prepuce and lips. A specific rabbit antihuman keratin antiserum was shown, by IF and inhibition studies, to have a different specificity from that of spontaneous human AKA. AKA were associated with the presence of subcutaneous nodules in RA (p = 0.05), but not with Raynaud''s phenomenon, Sjögren''s syndrome, or HLA-DR4 positivity. Rheumatoid factor (RF) was not associated with AKA either in RA or in RF-positive disease controls.     

Amyloidosis and aging

Amyloidosis is a heterogeneous group of extracellular protein deposition diseases. Age-related amyloidosis may be systemic or localized. The systemic forms include associated-myeloma AL amyloidosis and senile systemic amyloidosis which is the only clear-cut systemic form related to age and derived from normal transthyretin. In localized amyloidosis, the fibril protein precursors are synthesized in the tissue involved by the amyloid. In most cases, localized age-related amyloidosis does not appear to cause clinical disease with the exception of amyloid associated with Alzeihmer's disease and type 2 diabetes mellitus. The significance of aortic amyloidosis, amyloidosis of seminal vesicles, amyloid of the endocrine glands, and articular amyloidosis remains unknown.     

Differential expression of CD 180 and IgM by B-cell chronic lymphocytic leukaemia cells using mutated and unmutated immunoglobulin VH genes

We have studied the surface expression of the Toll-like receptor family member CD 180 on cells from 78 patients with B-chronic lymphocytic leukaemia (B-CLL). B-CLL cells had variable levels of CD 180 expression, but this was always less than that expressed by normal blood B cells and was stable for 24 months. Significantly higher levels of CD 180 were expressed by B-CLL cells with mutated IGVH genes compared with those using unmutated IGVH genes. This was in contrast to the higher levels of expression of surface immunoglobulin M by B-CLL cells using unmutated, rather than mutated IGVH genes. CD 180 was functional on B-CLL cells from some of the patients, as shown by the increased expression of CD 86 following incubation in vitro with anti-CD 180. The differential expression of CD 180 amongst B-CLL patients is one more marker that may define more precisely the different biological properties of this heterogeneous disease.     

Value of antibodies to citrulline-containing peptides for diagnosing early rheumatoid arthritis

OBJECTIVE: To compare the diagnostic values of antiperinuclear factor (APF), antikeratin antibody (AKA), and anti-cyclic citrullinated peptides (anti-CCP) to discriminate between patients with and without rheumatoid arthritis (RA) and to determine the diagnostic value of anti-CCP used alone or with other tests. METHODS: Two hundred and seventy patients with early arthritis underwent standardized investigations in 1995-1997. The clinical utility of APF, AKA, and anti-CCP in first-visit sera was evaluated using receiver-operating characteristic curves. Combinations of anti-CCP with other laboratory tests were assessed by multiple logistic regression. RESULTS: Anti-CCP, APF, and AKA were not perfectly correlated with one another. Anti-CCP with 53 UI as the cutoff was 47% sensitive and 93% specific, versus 52% and 79%, and 47% and 94%, for APF and AKA, respectively. Multiple logistic regression selected anti-CCP, AKA, IgM-rheumatoid factor (RF) ELISA, and the latex test. CONCLUSION: Rheumatologists can routinely use 2 or 3 tests for diagnosing RA (latex and/or IgM RF ELISA, and either AKA or anti-CCP ELISA) and can add a third or fourth test when the diagnosis remains in doubt.