The antibody response to respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a major focus of COVID-19 research due to its clinical relevance and importance in vaccine and therapeutic development. Neutralizing antibody (NAb) evaluations are useful for the determination of individual or herd immunity against SARS-CoV-2, vaccine efficacy, and humoral protective response longevity, as well as supporting donor selection criteria for convalescent plasma therapy. In the current manuscript, we review the essential concepts of NAbs, examining their concept, mechanisms of action, production, and the techniques used for their detection; as well as presenting an overview of the clinical use of antibodies in COVID-19.

The main expected result of a vaccine against viruses is the ability to produce neutralizing antibodies. Currently, several vaccines against SARS-CoV-2 are being applied to prevent mortal complications, being Pfizer-BioNTech (BNT162b2) one of the first to be authorized in the USA and Mexico (11 December 2020). This study evaluated the efficacy of this vaccine on antibody production with neutralizing capacity and its side effects in healthcare workers with and without prior SARS-CoV-2 infection and in a group of unvaccinated individuals with prior COVID-19. The main findings are the production of 100% neutralizing antibodies in both groups after the second dose, well-tolerated adverse effects, the possible presence of immunosenescence, and finally, we support that a single dose of this vaccine in individuals with prior COVID-19 would be sufficient to achieve an immunization comparable to people without prior COVID-19 with a complete vaccination program (2 doses).

This is the first study outside of clinical trials (phase I–III) evaluating the ability of the Ad5-nCoV vaccine to generate neutralizing antibodies and the factors associated with optimal or suboptimal response. In a longitudinal assay, 346 people (117 with prior COVID-19 and 229 without prior COVID-19) vaccinated with Ad5-nCoV were recruited. The percentage of neutralizing antibodies against SARS-CoV-2 (Surrogate Virus Neutralization Test) and antibodies against Ad5 (ADV-Ad5 IgG ELISA) were quantified pre and post-vaccination effects. The Ad5-nCoV vaccine induces higher neutralizing antibodies percentage in individuals with prior COVID-19 than those without prior COVID-19 (median [IQR]: 98% [97–98.1] vs. 72% [54–90], respectively; p < 0.0001). Furthermore, a natural infection (before vaccination) induces more neutralizing antibodies percentage than immunized individuals without prior COVID-19 (p < 0.01). No patient had vaccine-severe adverse effects. The age, antidepressant, and immunosuppressive treatments, reactogenicity, and history of COVID-19 are associated with impaired antibody production. The anti-Ad5 antibodies increased after 21 days of post-vaccination in all groups (p < 0.01). We recommend the application of a booster dose of Ad5-nCoV, especially for those individuals without previous COVID-19 infection. Finally, the induction of anti-Ad5 antibodies after vaccination should be considered if a booster with the same vaccine is planned.

B lymphocytes are essential elements of the adaptive immune response, performing critical functions such as antigen presentation, cytokine secretion, and antibody production. Their development follows a tightly regulated progression from hematopoietic stem cells to differentiated plasma or memory cells, orchestraeted by key transcriptional factors including PU.1, Ikaros, E2A, Pax-5, and BCL6. These factors govern gene expression essential for processes such as V(D)J recombination, somatic hypermutation, and immunoglobulin class switching—ensuring proper lineage commitment and the maintenance of immunological tolerance. Dysregulation of these pathways, whether through genetic or epigenetic alterations or chronic inflammatory stimuli, can result in autoimmunity, persistent inflammation, or B cell malignancies. This review provides a comprehensive analysis of the transcriptional and immunological mechanisms underlying B cell development and homeostasis, emphasizing their roles in disease pathophysiology and potential as therapeutic targets.

Background: Metabolic syndrome (MetS) prevalence in rheumatoid arthritis (RA) patients is known to vary considerably across the world. This study aimed to determine the prevalence of MetS in RA patients from western Mexico and to analyze the interrelation of the MetS components with the clinical variables of RA.Methods: This case‐control study included 216 RA patients and 260 control subjects (CS). MetS prevalence was determined according to the NCEP/ATP III and the Latin American Consensus of the Latin American Diabetes Association (ALAD) criteria.Results: MetS was observed in 30.6% RA patients and 33.3% of controls (p > 0.05) according to NCEP/ATP III and 28.7% in RA patients and 31.1% for controls using ALAD criteria. Total cholesterol, LDL‐C, and Castelli's I‐II indexes were lower in RA (p < 0.001) than in CS. The RA patients with MetS had more swollen joints than those without MetS (p = 0.018). In RA patients with MetS, DAS‐28 score correlated with smoking index (rho = 0.4601,p = 0.0004) and VLDL‐C (rho = 0.3108,p = 0.0056); similarly, rheumatoid factor (RF) correlated with age (rho = 0.2031,p = 0.0027), smoking index (rho = 0.3404,p < 0.0001), triglycerides (rho = 0.1958,p = 0.0039), and VLDL‐C (rho = 0.1761,p = 0.0162).Conclusions: The MetS prevalence in RA patients from western Mexico is not higher than controls; however, in RA patients with MetS, some inflammatory markers are associated with MetS components; thus, the control of MetS in RA could be beneficial to regulate disease activity.