CD19 and neoplasm: It was found that H22 cells had a strong uptake of tumor cell microparticles, reaching 45% and 100% at 8 h and 24 h, while the uptake of tumor cell‐derived microparticles by CD3+ T cells was less than 5% at 8 h; the uptake of CD19+ B cells was also less than 20% at 8 h.25