Characterization of CD22 expression in acute lymphoblastic leukemia

Pediatr Blood Cancer. 2015 Jun;62(6):964-9. doi: 10.1002/pbc.25410. Epub 2015 Mar 1.


Background: CD22 is a B-lineage differentiation antigen that has emerged as a leading therapeutic target in acute lymphoblastic leukemia (ALL).

Procedure: Properties of CD22 expression relevant to therapeutic targeting were characterized in primary samples obtained from children and young adults with relapsed and chemotherapy refractory B-precursor (pre-B) ALL.

Results: CD22 expression was demonstrated in all subjects (n = 163) with detection on at least 90% of blasts in 155 cases. Median antigen site density of surface CD22 was 3,470 sites/cell (range 349-19,653, n = 160). Blasts from patients with known 11q23 (MLL) rearrangement had lower site density (median 1,590 sites/cell, range 349-3,624, n = 20 versus 3,853 sites/cell, range 451-19,653, n = 140; P = <0.0001) and 6 of 21 cases had sub-populations of blasts lacking CD22 expression (22%-82% CD22 +). CD22 expression was maintained in serial studies of 73 subjects, including those treated with anti-CD22 targeted therapy. The levels of soluble CD22 in blood and marrow by ELISA were low and not expected to influence the pharmacokinetics of anti-CD22 directed agents.

Conclusions: These characteristics make CD22 an excellent potential therapeutic target in patients with relapsed and chemotherapy-refractory ALL, although cases with MLL rearrangement require close study to exclude the presence of a CD22-negative blast population.

Keywords: CD22; acute lymphoblastic leukemia; monoclonal antibody; relapse.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Chromosomes, Human, Pair 11
  • Histone-Lysine N-Methyltransferase
  • Humans
  • Infant
  • Myeloid-Lymphoid Leukemia Protein / genetics
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / drug therapy
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / immunology*
  • Sialic Acid Binding Ig-like Lectin 2 / analysis*
  • Sialic Acid Binding Ig-like Lectin 2 / antagonists & inhibitors


  • CD22 protein, human
  • KMT2A protein, human
  • Sialic Acid Binding Ig-like Lectin 2
  • Myeloid-Lymphoid Leukemia Protein
  • Histone-Lysine N-Methyltransferase