Agglutination of leukemic and 2,4-dinitrophenyl-tagged normal human lymphocytes by wheat germ agglutinin.

The present study was undertaken to determine if leukemic and 2,4-dinitrophenyl (DNP)-tagged normal human lymphocytes shared common receptors for Wheat Germ Agglutinin (WGA), a lectin capable of reacting with malignant cells. Normal peripheral blood lymphocytes were tagged with 2,4-dinitrofluorobenzene (DNFB) at a ratio of 10-11 molecules/cell. Various concentrations of WGA were added to leukemic or tagged or untagged normal lymphocytes and incubated for 20 minutes at 37 degrees C, after which agglutination was scored visually. A readily discernible quantitative difference in the agglutinability of leukemic and DNP-tagged versus untagged normal cells was seen at all concentrations of WGA in the range of 50-800 mug/ml. The reaction was maximal when a ratio of 10-11 molecules of DNFB/cell was used for tagging and decreased progressively with 10-8, 10-6, 10-4, 0r 10-2 molecules. The agglutination of leukemic and DNP-tagged normal lymphocytes by 200 mug/ml of WGA was completely blocked by 0.1 M N-acetylglucosamine (GlcNAc) while as low a concentration as 0.001 M GlcNAc inhibited the reactivity of untagged cells. Since the agglutination of leukemic and DNP-tagged normal lymphocytes was equally inhibited by GlcNAc, this suggests that the same or similar receptor sites were involved in the two reactions. On the basis of our observations we propose that the initial step in the agglutination of leukemic and DNP-tagged normal lymphocytes by WGA IS THE BINDING OF THE LECTIN TO SPECIFIC RECEPTORS RATHER Than to DNP residues on the cell surface, since leukemic cells tagged with DNFB did not show increased agglutinability.