Increased Rheumatoid Factor production in patients with severe COVID-19.

Background: Searching for Rheumatoid Factors (RF) in patients with coronavirus disease (COVID-19) has rarely been described.

Objectives: To investigate the association between RF isotypes (IgM, IgA, and IgG) and different clinical presentations of COVID-19 in a series of Tunisian patients.

Study Design: Eighty-two COVID-19 patients were enrolled in this study.

IgA is the predominant isotype of anti-β2 glycoprotein I antibodies in rheumatoid arthritis.

Background: The aim of this study was to determine the frequency of anti-cardiolipin antibodies (aCL) and anti-β2 glycoprotein I antibodies (aβ2GPI) among Tunisian patients with rheumatoid arthritis (RA).

Methods: Ninety RA patients with positive anti-cyclic citrullinated antibodies (anti-CCP) and 90 healthy blood donors (HBD) were studied. aCL and aβ2GPI of isotype IgG, IgA and IgM were detected by ELISA.