CD19 and non-Hodgkin lymphoma: The SIBC lines of this study presented CD19+/CD20+CD27+ memory B cells as a main population, while two AIDS‐NHL‐SIBC309 and HIV‐SIBC450 harbored a subpopulation of CD19+/CD20+CD27− naïve B cells, suggesting that SIBCs were derived from either a CD27‐ germinal center (GC) or CD27+ post‐GC B cell.