Expression of Leukemia-Associated Antigen, JL1, in Bone Marrow and Thymus

Abstract

The identification of immunophenotypic markers with restricted expression has long been a critical issue in diagnostic and therapeutic advances for acute leukemias. We previously developed a monoclonal antibody against a new thymocyte surface antigen, JL1, and showed that JL1 is expressed in the majority of acute leukemia cases. In this study, using multiparameter flow cytometric analyses, we found that JL1 was uniquely expressed in subpopulations of normal bone marrow (BM) cells, implying the association of JL1 with the differentiation and maturation process.

The Incidence and Immunophenotypic and Genetic Features of JL1 Expressing Cells and the Therapeutic Potential of an Anti-JL1 Antibody in De Novo Pediatric Acute Leukemias

“…The JL1 antigen is an epitope of CD43, a cell surface glycoprotein of the mucin family. It is also known as a differentiation antigen expressed on double positive (CD4 + CD8 + ) human cortical thymocytes [6789]. In normal bone marrow (BM), the JL1 antigen is expressed neither on hematopoietic pluripotent stem cells of myelomonocytic and erythroid lineages nor on mature blood cells (lymphocytes and segmented neutrophils) [789].…”

“…It is also known as a differentiation antigen expressed on double positive (CD4 + CD8 + ) human cortical thymocytes [6789]. In normal bone marrow (BM), the JL1 antigen is expressed neither on hematopoietic pluripotent stem cells of myelomonocytic and erythroid lineages nor on mature blood cells (lymphocytes and segmented neutrophils) [789]. In contrast, the JL1 antigen is heterogeneously expressed in myelomonocytic lineages (no or weak expression on promyelocytes, myelocytes, and metamyelocytes, but strong expression on band forms); in lymphoid lineages, JL1 antigen is expressed on common lymphoid progenitors and widely distributed during lymphoid maturation but is down-regulated during the final maturation process [789].…”

“…In normal bone marrow (BM), the JL1 antigen is expressed neither on hematopoietic pluripotent stem cells of myelomonocytic and erythroid lineages nor on mature blood cells (lymphocytes and segmented neutrophils) [789]. In contrast, the JL1 antigen is heterogeneously expressed in myelomonocytic lineages (no or weak expression on promyelocytes, myelocytes, and metamyelocytes, but strong expression on band forms); in lymphoid lineages, JL1 antigen is expressed on common lymphoid progenitors and widely distributed during lymphoid maturation but is down-regulated during the final maturation process [789]. The JL1 antigen has also been reported to be expressed on leukemic T, B, and myeloid lineage cells in >80% of acute leukemia patients and thus could serve as a potential candidate for immunotherapy [789].…”

“…In contrast, the JL1 antigen is heterogeneously expressed in myelomonocytic lineages (no or weak expression on promyelocytes, myelocytes, and metamyelocytes, but strong expression on band forms); in lymphoid lineages, JL1 antigen is expressed on common lymphoid progenitors and widely distributed during lymphoid maturation but is down-regulated during the final maturation process [789]. The JL1 antigen has also been reported to be expressed on leukemic T, B, and myeloid lineage cells in >80% of acute leukemia patients and thus could serve as a potential candidate for immunotherapy [789]. The overall incidence of JL1 positivity was reported to be 80.9%, 87.0%, and 90.1% in non-T ALL, T-ALL, and AML, respectively [7].…”

“…The JL1 antigen has also been reported to be expressed on leukemic T, B, and myeloid lineage cells in >80% of acute leukemia patients and thus could serve as a potential candidate for immunotherapy [789]. The overall incidence of JL1 positivity was reported to be 80.9%, 87.0%, and 90.1% in non-T ALL, T-ALL, and AML, respectively [7]. Preclinical studies have demonstrated the cytotoxic effects of an anti-JL1-based immunotoxin against JL1-positive leukemic cells, which does not affect most normal tissues other than thymocytes and certain mononuclear cells of the BM [10].…”