This research uses in-depth analysis of immune cell phenotype comparing sex and gender differences between young post-pubertal healthy and juvenile-lupus cis-men and cis-women, as well as in transgender individuals undergoing gender-affirming sex hormone treatment. During adolescence, rapid changes in sex hormones drive changes in inflammatory responses and disease susceptibility, therefore, this age range is important in the context of autoimmune research. Subsequent to the immune phenotype analysis results, this project pursued a particular focus on regulatory T-cells (Tregs), involving functional assays and complex analysis of RNA-sequencing data to investigate differences by sex and gender in healthy individuals and in juvenile-lupus patients. Collectively, the evidence from this study could be used to improve our understanding of sexual dimorphisms in immune responses by sex to improve sex and gender-specific therapeutic strategies in health and disease, as well as to understand sex differences in inflammatory responses, vaccine efficacy and autoimmune disease susceptibility.