Rare immunofluorescence patterns of autoantibodies on HEp-2 cells defined by ICAP identify different autoimmune diseases in the absence of associated specificities: a Spanish multicentre study

OBJECTIVES

ANA are the most extensively used test for the diagnosis of systemic autoimmune diseases. However, testing by indirect immunofluorescence assays (IIFAs) on HEp-2 cells, the gold standard test, is time-consuming and needs expertise. Thus there is a trend to replace it with other automated solid-phase assays directed against specific ANA. Nonetheless, the Hep-2 cell is an autoantigen array and ANA have been classified into 29 types, some of them with no clear association with a specificity to be detected. It is especially in these uncommon patterns where no clinical relationship is found and no antigenic specificity is detected. Here we retrospectively collected clinical data from patients with confirmed uncommon HEp-2 IIFA patterns to search for an associated clinical condition.

METHODS

We conducted an observational retrospective study including 608 patients with organ-specific and non-organ-specific autoimmune diseases (OSADs and NOSADs, respectively) with a confirmed rare pattern of ANA detected by IIFA on HEp-2 cells in the routine practice of the Spanish European Autoantibodies Standardization Initiative laboratories. Inclusion criteria are the existence of a minimum follow-up of 2 years and the availability of clinical data.

RESULTS

Nuclear patterns were more frequent in SLE (P = 0.001) and SS (P = 0.001), whereas the cytoplasmic ones were significantly higher in SSc (P = 0.022) and inflammatory myositis (P = 0.016). Mitotic patterns did not show any preferences for a specific disease and 62.7% of them corresponded to the nuclear mitotic apparatus pattern (AC-26). The most frequent NOSADs in patients with the AC-26 pattern were SLE (28.6%), SS (11.9%) and RA (11.9%). The cytoplasmic HEp-2 IIFA patterns were equally distributed in both groups of patients. In the OSAD patients there was no predominant pattern, except for AC-6 in primary biliary cholangitis due to Sp-100 antibodies (P < 0.001).

CONCLUSION

Detection of infrequent ANA might be a unique finding with no disease-associated specificities and could lead to the suspicion of an autoimmune disease.

Celiac disease and HLA-DQ genotype: diagnosis of different genetic risk profiles related to the age in Badajoz, southwestern Spain

BACKGROUND AND OBJECTIVES

celiac disease is associated with the HLA class II alleles: DQA1*05-DQB1*02 and DQB1*0302. The genetic risk for celiac disease may depend on the presence or absence of such alleles, their combination or number of copies. This study aimed to establish the differences in HLA genotypes between celiac patients diagnosed during childhood and adulthood, and between patients and healthy controls, and to determine the risk of disease in each genotypic category.

METHODS

we classified 350 celiac patients at time of diagnosis and 218 controls into 14 categories according to their HLA genotype, based on the presence or absence of risk alleles.

RESULTS

we found statistically significant differences between the genotype frequencies of celiac patients diagnosed as being children and adults. DQA1*05 (x 1 copy), DQB1*02 (x 1 copy), DQB1*0302 (x 0 copies) was the most frequent genotype in individuals diagnosed in childhood, whereas DQA1*05 (x 1 copy), DQB1*02 (x 2 copies), DQB1*0302 (x 0 copies) was the most frequent in adults. The risk for disease in each genotypic category in celiac children and adults turned out to be different. The presence of DQB1*0302 did not increase risk in children, but did in adults.

CONCLUSION

in our celiac population, we found a different genetic pattern according to age of diagnosis. That could suggest that the pathogenic mechanism of the disease is not exactly the same in both age groups, which could somehow determine clinical presentation of the disease, its epidemiology, coexisting diseases, and complications.