Cluster analysis-based subgroup classification based on CD8 cell differentiation and activation revealed a group with high numbers of activated CD8+ T cells, highly active SLE and organ damage, including active nephritis and persistently high cell counts after a 24-week treatment, indicating treatment resistance (high anti-dsDNA antibody titres and high glucocorticoid doses). The gene discussed is CD8A; the disease is systemic lupus erythematosus.