Leukemia diagnosis and testing of complement-fixing antibodies for bone
marrow purging in acute lymphoid leukemia
D Campana and G Janossy
In this paper a microplate method is described for diagnosing acute
leukemia and for investigating the reactivity of monoclonal antibodies
(MoAbs) against membrane antigens in combination with rabbit or murine
antibodies to nuclear terminal transferase (TdT). The speed of this method
facilitates the investigation of fresh leukemic cells from individual
patients and assesses the cytolytic efficacy of the relevant MoAbs in the
presence of complement (C'). Lymphoblasts (TdT+) are mixed in equal
proportions with known numbers of "inert" cells, eg, RBC or nonleukemic
bone marrow (BM). Following incubation with MoAbs and C' the ratio of
residual TdT+ cells and inert cells is determined on cytospin preparations.
Initially, percentages of TdT+ cells are counted in a unit volume of 5,000
inert cells, followed by the scanning of greater than 2 X 10(4) inert cells
on entire slides. With this method more than 4 log cytoreduction of TdT +
cells is detected. The method is also applicable for studying the cytolysis
of malignant B cells by using mostly monoclonal lg expression rather than
TdT for the identification of residual B cells. Ten representative patients
selected from a group of greater than 100 are reported. In some cases
cytoreduction of greater than 4 log with no identifiable residual TdT +
cells is achieved by a single C'-fixing MoAb: anti-CD10 (RFAL3) in common
acute lymphoid leukemia (ALL) and anti-CD7 (RFT2) in T cell ALL (T-ALL).
Other cases require cocktails of anti-CD10, anti-CD19, and anti-CD24 in
common ALL or anti-CD7 and anti-CD8 in T-ALL. In T-ALL a few TdT + cells
remain that exhibit the features of normal TdT + BM cells (CD7-, HLA-DR+).
This is particularly noticeable when patients are studied in partial
remission or if nonleukemic BM is used as a source of inert cells. The
methods described here contribute to establishing a range of MoAbs (ie, of
IgM class) and techniques for efficient purging and to comparing the
efficacy of "clean-up," in remission, of common ALL, T-ALL, and B cell
malignancies.
Volume 68,
Issue 6,
pp. 1264-1271,
12/01/1986
Copyright © 1986 by The American Society of Hematology
