Differential endocytosis of fluorescein iso-thiocyanate-concanavalin A by normal and chronic myeloid leukemic granulocytes.

Isolated granulocytes from normal individuals and patients suffering from chronic myeloid leukemia (CML) displayed different fluorescent patterns on treatment with fluorescein isothiocyanate concanavalin A (Fl-Con A). The ligand was internalized by 86% of the normal granulocytes, while 80% of the leukemic granulocytes exhibited Fl-Con A localized on the cell periphery. In further experiments, pretreatment of the normal granulocytes with cytochalasin B, iodoacetamide, 2-deoxyglucose and sodium fluoride (but not with sodium azide or dinitrophenol) was found to drastically inhibit internalization of the ligand. However, pretreatment of granulocytes from CML patients with cytochalasin B and 2-deoxyglucose, caused only a little alteration in the pattern of Fl-Con A labelling relative to untreated cells. These results indicate that CML granulocytes are defective in their ability to endocytose Fl-Con A. We suggest that this differential interaction between Fl-Con A and normal and leukemic granulocytes is a convenient system to study the initial steps in receptor mediated endocytosis of Concanavalin A.

Studies on granulocyte functions in patients with chronic myeloid leukemia.

Granulocyte functions, viz. endocytosis, NADPH oxidase activity and iodination by leukocytes, were studied in granulocytes isolated from 17 chronic myeloid leukemia (CML) patients at initial diagnosis (stage I), from 10 patients in relapse (stage II), and 10 patients in acute blastic crisis (stage III). The mean phagocytic index of granulocytes from CML patients was similar to the normal value. NADPH activity decreased as the disease progressed. Thus, the amount of formazan produced was lower in granulocytes from patients in stage II (P less than 0.05) and stage III (P less than 0.01) than that produced by normal granulocytes. H2O2-Myeloperoxidase-dependent iodination was found to be significantly reduced in granulocytes from all stages of the disease compared to that of normal, stage I (P less than 0.01), stage II (P less than 0.05) and stage III (P less than 0.01). It thus seems that granulocyte function becomes less efficient as the disease progresses towards acute blastic crisis. Immature cells from the same patients carried out these functions at a more reduced level than did their mature counterparts.

Defective chemotaxis and adherence in granulocytes from chronic myeloid leukemia (CML) patients.

Adherence and motility of granulocytes from chronic myeloid leukemia (CML) patients was compared with that of granulocytes from normal subjects. The percentage of non-adherent granulocytes was significantly higher in untreated CML patients and patients in relapse and acute blastic crisis (ABC) (P less than 0.01). Chemotactic Index (C.I.) of granulocytes moving in a gradient of a synthetic chemoattractant F-Met-Leu-Phe was measured by time-lapse cinématography. While 84.5 +/- 3.53% of normal granulocytes were motile, only 30.3 +/- 14.7% granulocytes from untreated patients, 33.8 +/- 21.3% granulocytes from relapse patients and 36 +/- 9.9% granulocytes from ABC patients were found to be motile. The C.I. of motile granulocytes from CML patients was significantly lower in untreated patients (P less than 0.05), in patients in relapse (P less than 0.01) and in patients in ABC (P less than 0.05), as compared to that of normal granulocytes. Visualization of cytoplasmic actin by indirect immunofluorescence, revealed the presence of actin in granulocytes from patients in all stages of the disease. Thus, granulocytes from CML patients were defective in directional locomotion. Organized actin filaments were found in the small percentage of motile cells still found in CML patients.