914 USE OF MONOCLONAL ANTIBODIES TO DIAGNOSE CENTRAL NERVOUS SYSTEM LEUKEMIA

Abstract

The early identification of small numbers of leukemic cells in cerebrospinal fluid (CSF) presents a diagnostic problem in the treatment of children with acute lymphoblastic leukemia (ALL). We used a latex sphere rosetting technique to identify monoclonal markers on CSF lymphocytes in 201 samples from 112 children with ALL. Spinal fluid samples were incubated with mouse monoclonal antibodies against CALLA (J5), Ia, Bl, or OKT 11. Presence of monoclonal antibodies on cells was determined by their ability to rosette 3 or more latex spheres bound with goat anti-mouse antibody. Cells were then cytocentrifuged and Wright stained for sumultaneous examination of cell morphology and immune markers. In children without leukemic meningitis only 3% of CSF lymphoid cells were J5 (CALLA) positive, 8% were positive for Ia, 16% were positive for Bl and 69% were positive for OKT 11. Similar percentages were found in 15 adults having myelograms done. In contrast, in 5 children with CSF lymphoblasts seen, larger numbers of J5 or Ia positive cells were seen (24%-92%), sometimes with decreased numbers of OKT 11 positive cells (3-23%). In two children with small numbers of blast-like cells but with normal monoclonal markers subsequent CSF examinations were normal. We conclude that the use of this methodology provides valuable information complimentary to that obtained by examination of CSF samples for morphology alone.