Summary. P-glycoprotein (PGP) lung resistance protein (LRP) and multidrug resistance associated protein (MRP) expressions and function were evaluated by flow cytometry in 65 leukaemic patients (38 acute non-lymphocytic leukaemias, eight acute lymphocytic leukaemias, 19 Ph-positive chronic myeloid leukaemias in blastic phase). By using the MRK-16, the LRP-56 and the MRPm6 MoAbs, 34% of the cases did not over-express any proteins (¹); 24 . 5% overexpressed (þ) only PGP, 11% only LRP, 1 . 5% only MRP, 24 . 5% both PGP and LRP, and 4 . 5% both PGP and MRP. The mean intracellular daunorubicin accumulation (IDA) and rhodamine 123 (Rh123) retention in the presence or absence of the reversal agent SDZ PSC 833 (PSC) of the PGP ¹ /LRP ¹ /MRP ¹ cases were comparable to the ones observed in normal leucocytes. With respect to the non-overexpressing cases, the PGP ¹ /LRP þ /MRP ¹ cases showed only an impaired IDA (mean 204 Ϯ 29; P < 0 : 001). The PGP þ / LRP þ /MRP ¹ cases had a defect both in IDA (mean 166Ϯ 47, P < 0 : 001) and Rh123 retention (mean 0 : 42 Ϯ 0 : 14; P < 0 : 001), which were both corrected by PSC. All the PGP þ / LRP þ /MRP ¹ cases had a defect in IDA (mean daunorubicin (DNR) accumulation 192 Ϯ 44; P < 0 : 001Þ. However, only in 8/16 of them an evident defect in Rh123 retention was found. In conclusion, both PGP and LRP over-expression were common in leukaemia. An impaired IDA was found in all cases over-expressing PGP, LRP or both. The study of Rh123 retention could give incorrect information about the blast cells' ability to accumulate cytotoxic drugs in patients over-expressing both PGP and LRP.

The biologic and clinical importance of the multidrug resistance (MDR) that is related with the overexpression of the P170 glycoprotein (Pgp) is widely recognized. However, a major issue that has not yet been solved is the definition of the degree of Pgp expression which is associated with a significant decrease of the sensitivity of the cells to chemotherapy. For this reason we studied the leukemic cells from 83 cases of acute leukemia. Leukemic cells were fixed in PLP and treated with saponine. Pgp expression was assayed by flow cytometry, using the anti Pgp monoclonal antibody MRK-16. Results were expressed both as the number of positive cells and by the intensity of the reaction as defined by the mean fluorescence index (MFI), i.e. the ratio between the mean fluorescence intensity of the MRK-16 incubated cells and of the IgG2a incubated cells. Thus, Pgp expression was compared with the results of two in vitro tests of cell sensitivity to anthracyclines, daunorubicin (DNR) cell retention and DNR cytotoxicity. We found that it was not the number of MRK-16 positive cells, but the degree of the reaction with MRK-16 (MFI) that significantly related to the anthracycline toxicity tests. Therefore, we propose that for clinical purposes a quick and cheap determination of Pgp-related MDR in leukemic cells may be obtained by measuring the MFI with MRK-16 in a standard flow cytometry assay and that the assay may indeed be sufficient to estimate Pgp expression as well as the influence of Pgp on cell sensitivity to anthracyclines.

Although a large amount of data is available on the effects of filgrastim (granulocyte colony-stimulating factor [G-CSF]) on the mobilization of stem cells in the circulation, data concerning its effects on bone marrow (BM) harvesting is scarce and controversial. We have designed a randomized trial comparing filgrastim-mobilized peripheral blood stem cell (PBSC) transplantation with filgrastim-primed autologous bone marrow transplantation (ABMT). Fifty-five patients affected by non-Hodgkin's (n = 38) or Hodgkin's (n = 17) lymphoma, selected for autologous transplantation over a 12-month period in a single institution, were randomized 2:1 to undergo BM or PB harvest/collection after priming for 3 days with filgrastim, 16 μg/kg body weight daily subcutaneously. BM priming with G-CSF allowed the harvest of a significantly higher number of mononuclear cells (MNC) (0.53 × 108/kg, range, 0.32 to 1.40), as compared with a historical control of unprimed BM harvests (0.43 × 108 MNC/kg, range, 0.15 to 0.72, P = .001). After high-dose ablative therapy, median time to neutrophil recovery above 0.5 × 109/L was 12 days for BM and 11 days for PB (P = .219); median time to platelet recovery above 20 × 109/L was 13 days for BM and 11 days for PB (P = .242). The same number of red blood cells, platelet transfusions, and posttransplant G-CSF doses were required in the two groups of patients. Less patients (50% v 70%) became febrile in the group transplanted with mobilized PB, but days of fever/patient and days on antibiotics were overlapping. The median time spent in the hospital after reinfusion was 16.5 and 15.5 days after primed BM and primed PB, respectively (P = .134). These data suggest that in patients with lymphoma submitted to autologous transplantation, the reinfusion of filgrastim-primed BM or filgrastim-mobilized PB leads to similar results, with an advantage of only 1 day in the neutrophil recovery and 1 day on the time spent in the hospital in favor of primed PB. Either option can be chosen on the basis of the availability of a surgery room or cell separator facilities and considering the patients' characteristics and wishes.

Although a large amount of data is available on the effects of filgrastim (granulocyte colony-stimulating factor [G-CSF]) on the mobilization of stem cells in the circulation, data concerning its effects on bone marrow (BM) harvesting is scarce and controversial. We have designed a randomized trial comparing filgrastim-mobilized peripheral blood stem cell (PBSC) transplantation with filgrastim-primed autologous bone marrow transplantation (ABMT). Fifty-five patients affected by non-Hodgkin's (n = 38) or Hodgkin's (n = 17) lymphoma, selected for autologous transplantation over a 12-month period in a single institution, were randomized 2:1 to undergo BM or PB harvest/collection after priming for 3 days with filgrastim, 16 μg/kg body weight daily subcutaneously. BM priming with G-CSF allowed the harvest of a significantly higher number of mononuclear cells (MNC) (0.53 × 108/kg, range, 0.32 to 1.40), as compared with a historical control of unprimed BM harvests (0.43 × 108 MNC/kg, range, 0.15 to 0.72, P = .001). After high-dose ablative therapy, median time to neutrophil recovery above 0.5 × 109/L was 12 days for BM and 11 days for PB (P = .219); median time to platelet recovery above 20 × 109/L was 13 days for BM and 11 days for PB (P = .242). The same number of red blood cells, platelet transfusions, and posttransplant G-CSF doses were required in the two groups of patients. Less patients (50% v 70%) became febrile in the group transplanted with mobilized PB, but days of fever/patient and days on antibiotics were overlapping. The median time spent in the hospital after reinfusion was 16.5 and 15.5 days after primed BM and primed PB, respectively (P = .134). These data suggest that in patients with lymphoma submitted to autologous transplantation, the reinfusion of filgrastim-primed BM or filgrastim-mobilized PB leads to similar results, with an advantage of only 1 day in the neutrophil recovery and 1 day on the time spent in the hospital in favor of primed PB. Either option can be chosen on the basis of the availability of a surgery room or cell separator facilities and considering the patients' characteristics and wishes.

Sea-blue histiocytosis is a morphological finding that can be associated both with acquired conditions of increased cellular turnover and inborn errors of lipid metabolism. We report a rare case of sea-blue histiocytosis associated with a mild phenotype of Niemann-Pick disease (NPD) type B in a 44-year-old man who presented with splenomegaly and mild thrombocytopenia. Diagnosis was guided by the morphological finding in bone marrow smears of foamy and sea-blue histiocytes and confirmed by the measurement of acid lysosomal sphingomyelinase activity below normal values. NPD type B is a rare inborn error of metabolism, with a benign course and prognosis, while types A and C are always associated with severe neurological involvement. In our patient diagnosis was confirmed by the specific enzyme assay of leukocytes (deficiency in sphingomyelinase activity). This is a simple and noninvasive method that is useful whenever clinical and morphological finding are relevant, and a primary hematological disorder has been ruled out.