Background: Macrophage migration inhibitory factor (MIF) is a cytokine capable of stimulating inflammatory cytokine and matrix metalloproteinase production from macrophages and synovial fibroblasts, which leads to persistent inflammation and bone degradation, two of the major pathological processes in rheumatoid arthritis (RA). The aim of this study was to evaluate the association of MIF promoter polymorphisms (−794CATT 5-8 rs5844572 and −173G > C, rs755622), circulating MIF levels, and mRNA expression with RA susceptibility and disease activity. Methods: A case-control study was conducted in 200 RA patients and 200 control subjects (CS) from Southern Mexico. Genotyping was performed by conventional PCR and PCR-RFLP methods. MIF mRNA expression was quantified by real-time PCR and MIF serum levels were determined by an ELISA kit. Results: The 7,7 (−794CATT 5-8 ) and −173CC (−173G > C) genotypes were associated with higher disease activity in RA patients. MIF serum levels were increased, and MIF mRNA expression was reduced in RA patients as compared to CS. In addition, RA patients with moderate disease activity had higher MIF levels than those with low disease activity. The −794CATT 5-8 and −173G > C MIF polymorphisms were not associated with RA susceptibility. Conclusion: These results suggest an important role of MIF polymorphisms and MIF serum levels with disease activity in RA. K E Y W O R D SDAS28, genetic susceptibility, MIF, polymorphisms, rheumatoid arthritis

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Purpose Understanding the humoral immune response dynamics carried out by B cells in COVID-19 vaccination is little explored; therefore, we analyze the changes induced in the different cellular subpopulations of B cells after vaccination with BNT162b2 (Pfizer-BioNTech). Methods This prospective cohort study evaluated thirty-nine immunized health workers (22 with prior COVID-19 and 17 without prior COVID-19) and ten subjects not vaccinated against SARS-CoV-2 (control group). B cell subpopulations (transitional, mature, naïve, memory, plasmablasts, early plasmablast, and double-negative B cells) and neutralizing antibody levels were analyzed and quantified by flow cytometry and ELISA, respectively. Results The dynamics of the B cells subpopulations after vaccination showed the following pattern: the percentage of transitional B cells was higher in the prior COVID-19 group ( p < 0.05), whereas virgin B cells were more prevalent in the group without prior COVID-19 ( p < 0.05), mature B cells predominated in both vaccinated groups ( p < 0.01), and memory B cells, plasmablasts, early plasmablasts, and double-negative B cells were higher in the not vaccinated group ( p < 0.05). Conclusion BNT162b2 vaccine induces changes in B cell subpopulations, especially generating plasma cells and producing neutralizing antibodies against SARS-CoV-2. However, the previous infection with SARS-CoV-2 does not significantly alter the dynamics of these subpopulations but induces more rapid and optimal antibody production.