Peter R. Galbraith

Use of the mtt assay for rapid determination of chemosensitivity of human leukemic blast cells

A microcytotoxicity assay employing a tetrazolium salt has been adapted for testing the response of human leukemic blast cells to a variety of chemotherapeutic agents. After exposure to various concentrations of drugs, the viability of fresh leukemic blast cells was measured using a tetrazolium salt, MTT, which is converted to blue formazan crystals by living cells. The amount of formazan produced was quantitated using a microtitre plate spectrophotometer. In the present study, optimal conditions for chemosensitivity testing of human leukemia samples were determined, and the relative chemosensitivity of five patient samples was tested.

Studies of human natural killer cells. III. Neutropenia associated with unusual characteristics of antibody-dependent and natural killer cell-mediated cytotoxicity

A 52-year-old Caucasian man with chronic neutropenia and recurrent infections was found to have an increased proportion of peripheral T lymphocytes having Fc receptors for IgG (T(γ). Although levels of antibody-dependent cell-mediated cytotoxicity (ADCC) and “natural” killing (NK) by unfractionated lymphocytes were similar to those of a control donor, the frequency of NK cells was markedly increased. Removal of E rosette-forming cells eliminated both NK and ADCC by the patients peripheral blood, in marked contrast to theenhanced cytotoxicity seen with control lymphocytes. Both normal and patient ADCC and NK functions were removed by depletion of Fc receptor-bearing cells. These depletion experiments proved that all of the patients killer cells were E rosetteforming Tγ cells, in contrast to the heterogeneous pattern of Nullγ and Tγ killer cells seen in the blood of normal donors. The homogeneity of the Tγ proliferation suggested that ADCC and NK were mediated by the same cell type, albeit acting by different mechanisms. The addition of the patients serum and lymphocytes to chromiumlabeled normal granulocytes caused a low but significant level of cytotoxicity, indicating that the patients neutropenia may have been caused by a similar mechanismin vivo. There was no evidence of complement-dependent serum antibody-mediated neutrophil lysis, but one serum sample taken over the course of the patients disease agglutinated granulocytes from four of five donors tested.

Absence of allelic loss on chromosome 5q by RFLP analysis in preleukemia

Thirty-eight patients with various forms of myelodysplastic syndrome (MDS) were studied for the loss of restriction fragment length polymorphism (RFLP) heterozygosity on chromosome 5q as inferential support for the presence of a growth regulatory locus in this area of the genome. Conventional chromosomal analysis was performed in addition to RFLP studies of constitutive and granulocyte DNA using five polymorphisms from chromosome 5. Allelic loss in granulocyte DNA was identified in only one patient in whom monosomy 5 had already been defined cytogenetically. These results suggest that DNA sequence loss from chromosome 5q other than that observed cytogenetically is a rare event in MDS. Thus the potential involvement of a growth regulatory gene(s), from this area of the genome, in the leukemogenic process most likely involves a more subtle genetic change.

The Mechanism of the Leukocytosis in Chronic Myelogenous Leukemia.

Excerpt Leukokinetic studies were performed in 11 subjects with chronic myelogenous leukemia (CML) by labeling leukocytes in vitro with diisopropyl fluorophosphate and returning them to the circula...

Effect of Lithium on Colony Formation and Production of Colony-Stimulating Factor

Lithium is a unique and simple agent which has depressant effects on a wide variety of synthetic processes in different organs (Singer and Rotenberg, 1973), and yet has a stimulatory effect on granulopoiesis (Murphy et al., 1971; Tisman et al., 1973; Gupta et al., 1976). Its potential as a therapeutic agent in Felty’s syndrome is now well known, and future uses remain to be clearly defined. Lithium has been reported to stimulate production of colony-stimulating factor (CSF), a putative regulator of granulopoiesis (Gupta et al., 1976; Harker et al., 1977). Lithium has also been reported to enhance the action of CSF (Morley and Galbraith, 1978).