CD28 and leukemia: Similarly, FCMR and SELL levels are increased in the plasma of CLL patients.39,40 CD48 expression is upregulated in MGUS and MM cells and soluble CD48 is increased in the serum of patients with leukemia or lymphoma.41,42 LY9 (CD229) serum levels are increased in MM patients at diagnosis.43 Key novel prediagnostic plasma markers for lymphoid malignancy development identified in our current study include: CD72, CD28 and SLAMF6 for CLL, FDCSP, CD72, CD28, LAG3 and INSL4 for DLBCL, FDCSP, CD72 and CD28 for FL, TACI and FCRLB for MM.