Antinuclear antibodies detected by Enzyme-Linked Immunosorbent Assay (ELISA) in severe COVID-19: clinical and laboratory associations

OBJECTIVE

Antinuclear antibodies (ANA) are detected in approximately a quarter of COVID-19 patients when assessed by indirect immunofluorescence. Since there is no information, our study investigated the presence of ANA detected by Enzyme-Linked Immunosorbent Assay (ELISA) and its clinical and laboratory associations.

PATIENTS AND METHODS

A longitudinal study was conducted on 92 patients with severe COVID-19, 20 patients with acute myocardial infarction, and 25 healthy subjects. Blood samples were obtained at hospital admission. Commercial ELISA was used to detect ANA, while flow cytometry was used to measure serum interferons.

RESULTS

ANAs were positive in 8.6% of COVID-19 patients, 10% of myocardial infarction patients, and 4% in healthy individuals (p=0.676). COVID-19 patients with ANA+ had less ferritin, troponin, and neutrophils but more albumin and lymphocytes than ANA- patients. Serum levels of type I, II, and III interferons were similar between groups. At follow-up, all ANA+ patients survived, while mortality was significant in ANA- patients (0 vs. 36%; p=0.048).

CONCLUSIONS

ANA detection is not increased in severe cases of COVID-19 when assessed by ELISA. However, its presence appears to be associated with a less aggressive disease phenotype, regardless of circulating levels of interferons.

The presence of IFL3/4 rs12979860 C allele influences the in vitro IP-10 production by mononuclear cells from patients with systemic lupus erythematosus

OBJECTIVE

To explore whether the IFNL3/4 rs12979860 genotype may influence serum levels or production of interferon-inducible protein-10 (IP-10) by peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE).

METHODS

Sixty-six patients with SLE and 22 healthy blood donors (controls) were included. The IFNL3/4 rs12979860 polymorphism was genotyped by real-time polymerase chain reaction. IP-10 levels in sera supernatants of IFNα stimulated peripheral blood mononuclear cells were measured by enzime-linked immunosorbent assay.

RESULTS

Allelic frequencies were CC (29%), CT (52%) and TT (20%) in SLE, and CC (32%), CT (41%) and TT (27%) in healthy controls. Median serum IP-10 levels were higher in SLE patients than in controls (190.8 versus 118.1 pg/ml; p < 0.001), particularly in those with high disease activity (278.5 versus 177.2 pg/ml; p = 0.037). However, serum IP-10 levels were not influenced by IFNL3/4 genotypes. Higher IP-10 production by peripheral blood mononuclear cells was found in both SLE patients (median 519.3 versus 207.6 pg/ml; p = 0.012) and controls (median 454.0 versus 201.7 pg/ml; p = 0.034) carrying the IFNL3/4 C allele compared with carriers of the T allele.

CONCLUSIONS

Although IFNL3/4 rs12979860 allele C does not appear to influence serum IP-10 levels in SLE, it plays an important role in the production of IP-10 by peripheral blood mononuclear cells after IFNα stimulation.