ALBERT

Description: A patient with an X-linked genetic disease resembling chronic granulomatous disease (CGD) but differing in several aspects from previously studied cases is described. The oxidase enzyme of the patient's granulocytes was normally activated, but had reduced activity as shown by an increased Michaelis constant and decreased maximum velocity of NADPH-dependent superoxide production. Cytochrome-b was undetectable in dithionite difference spectra. This CGD-like disease further implicates cytochrome-b as an important component of the microbicidal NADPH oxidase system and provides insight into its role in the enzyme complex.

Description: Stimulation of granulocyte (PMN) superoxide (O2-) production by concanavalin-A (Con-A) can be monitored continuously in the spectrophotometer. Both the rate of activation and final activity of the O2--generating system is dependent on the concentration of Con-A. Alpha methylmannoside (alpha MM) can prevent Con-A, but not phorbol myristate acetate (PMA) or zymosan, induced O2- production. Alpha MM inhibits both the rate of activation and the final rate of O2- production. When alpha MM is added after the attainment of a maximal rate of O2- production with Con-A, O2- production continues for another minute before it ceases. When PMA is added to such treated cells, it restores O2- production. Although the inhibition of O2- production by alpha MM on previously activated cells requires time, most of the bound concanavalin-A is removed immediately after the addition of alpha MM. Treatment of cells with L-1-tosylamido-2-phenylethyl-chloromethyl ketone (TPCK) prevents activation of PMN by Con-A to a greater extent than it does for either PMA or zymosan. TPCK has no effect on the binding of Con-A. TPCK, when added after Con-A, will inactivate O2- production by the cells. The addition of PMA after TPCK treatment restores O2--generating activity. Membrane-enriched particles from PMN activated with Con-A, alpha MM, and PMA demonstrate that the change in O2- production seen by whole cells is due to an alteration of the activity of the NADPH oxidase. Thus, Con-A stimulation of human PMN O2- production can be prevented and reversed by the addition of either alpha MM or TPCK and that PMA can reactivate Con-A and either alpha MM- or TPCK-treated cells. The activation, inactivation, and reactivation occur as a result of changes in the plasma membrane NADPH-dependent O2-- generating enzyme.

Description: The promyelocytic leukemia cell line, NB4, carries the t(15; 17) translocation and undergoes limited maturation in response to differentiation agents. Growth on laminin enhanced the ability of all- trans retinoic acid (ATRA) to promote morphologic maturation of these cells. Although exposure to ATRA in suspension yielded minimal maturation beyond the myelocyte stage, after 72 hours of exposure to ATRA on laminin the cells acquired the histologic appearance of metamyelocytes, band forms, and segmented neutrophils. After 96 hours, some cells acquired a spindle shape and became tightly adherent. Growth on collagen types I, III, IV, or fibronectin did not have this effect, although some cells did adhere to fibronectin. NB4 cells treated with ATRA in suspension or on laminin acquired the equivalent ability to reduce nitroblue tetrazolium or cytochrome C. Despite the improved morphologic maturation on laminin, the cells did not express secondary granule proteins such as lactoferrin or neutrophil collagenase. In addition, growth on laminin abolished cell proliferation in the presence of ionomycin. Growth on laminin and/or with ATRA induced new expression of alpha 6 integrin, a laminin receptor, as assessed by reverse transcription-polymerase chain reaction. Different conditions of growth (laminin or differentiation agent) resulted in specific patterns of expression of the alpha 6A and alpha 6B isoforms. Treatment with ATRA also resulted in the acquisition of high-level surface expression of alpha 6 integrin, as assessed by flow cytometry. Thus, treatment of NB4 promyelocytic leukemia cells with ATRA induced expression of alpha 6 integrin (a laminin receptor alpha-chain) and enabled more advanced maturation when the cells were grown on the extracellular matrix component, laminin, compared with tissue culture plastic.

Description: We have used a cloned cDNA for the major human selenoprotein, glutathione peroxidase (GPx), to assess the mode of regulation of human GPx gene (GPX-1) expression by selenium. When the HL-60 human myeloid cell line is grown in a selenium-deficient medium, GPx enzymatic activity decreases 30-fold compared with selenium-replete cells. Upon return to a medium containing selenium in the form of selenite, GPx activity in the cells starts to increase within 48 hours and reaches maximal (selenium-replete) levels at 7 days. Steady-state immunoreactive protein levels correlate with enzymatic activity. Cycloheximide inhibits the rise in GPx activity that accompanies selenium replenishment, indicating that protein synthesis is required for the increase. However, GPx mRNA levels and the rate of transcription of the human GPx gene change very little and thus appear to be independent of the selenium supply. Thus the human GPx gene appears to be regulated post-transcriptionally, probably cotranslationally, in response to selenium availability.

Description: The present studies document the cellular and biochemical processes involved in granulocyte O2- production in three patients from two kindreds with variant chronic granulomatous disease (CGD). Rates of O2- production were 9% to 30% of normal, depending on the individual tested and the stimulus; the two brothers from one family responded to each stimulus with rates very similar to each other. Kinetic analysis of NADPH-dependent O2- production in subcellular fractions revealed all three to have NADPH oxidases with both diminished substrate affinity for NADPH (high Kmapp) and decreased maximal velocities of O2- production. Their granulocytes had normal lag times for activation of the respiratory burst but abnormal rates of stimulus-induced membrane depolarization. Cytochrome b was not found in granulocytes or subcellular fractions despite the use of a spectrophotometric assay sensitive enough to detect the cytochrome if its content were proportional to the residual rate of O2- generation. A striking finding in one patient from each kindred was a threefold to tenfold decrease in the rate of O2- production accompanying serious infection. The residual O2(-)-generating activity of CGD variants helps to explain their relative freedom from the recurrent infections of the classic disease. However, the marked decrease described in the present study indicates the potential for a vicious cycle in which an infection, once established, leads to increasing impairment of host defense.

Description: Phagocytic cells generate superoxide in response to stimulation by opsonized particles. A continuous assay for opsonized zymosan- stimulated granulocyte superoxide production shows that there is a lag time between the addition of particles and the onset of detectable superoxide production. Superoxide production is preceded by membrane potential depolarization. Neither superoxide production nor membrane depolarization occurs in granulocytes from patients with chronic granulomatous disease. The extent of activation by opsonized zymosan is affected by the dose of zymosan from 0.5 to 4.5 mg/ml, but the time necessary for activation (lag time) is not. Similarly, the extent of depolarization but not the time necessary for attaining maximum depolarization is concentration-dependent. Effects of temperature, divalent cations, 2-deoxyglucose, cyanide, and N-ethyl maleimide on superoxide production are similar for granulocytes treated with soluble stimuli and with opsonized zymosan. Thus, zymosan stimulates granulocytes to generate superoxide and undergo membrane depolarization in a manner similar to that elected by soluble stimuli.

Description: The present studies document the cellular and biochemical processes involved in granulocyte O2- production in three patients from two kindreds with variant chronic granulomatous disease (CGD). Rates of O2- production were 9% to 30% of normal, depending on the individual tested and the stimulus; the two brothers from one family responded to each stimulus with rates very similar to each other. Kinetic analysis of NADPH-dependent O2- production in subcellular fractions revealed all three to have NADPH oxidases with both diminished substrate affinity for NADPH (high Kmapp) and decreased maximal velocities of O2- production. Their granulocytes had normal lag times for activation of the respiratory burst but abnormal rates of stimulus-induced membrane depolarization. Cytochrome b was not found in granulocytes or subcellular fractions despite the use of a spectrophotometric assay sensitive enough to detect the cytochrome if its content were proportional to the residual rate of O2- generation. A striking finding in one patient from each kindred was a threefold to tenfold decrease in the rate of O2- production accompanying serious infection. The residual O2(-)-generating activity of CGD variants helps to explain their relative freedom from the recurrent infections of the classic disease. However, the marked decrease described in the present study indicates the potential for a vicious cycle in which an infection, once established, leads to increasing impairment of host defense.

Description: A long-term bone marrow culture system has been derived for maintenance and proliferation of human hemopoietic stem cells and granulocytes in vitro for up to 20 wk. The granulocytes generated in these cultures at 8 wk were comparable to fresh human peripheral blood granulocytes in physiologic properties, including phagocytosis, degranulation, respiratory burst, and bacterial killing: individual granulocytes generated up to 20 wk in several cultures demonstrated normal superoxide-generating capacity by NBT dye reduction slide test. Thus, human granulocytes generated in continuous marrow culture retain many biologic functions associated with bacterocidal capacity in vivo and indicate that this system should be of value in studies of disorders of granulocyte differentiation.

Description: We describe a patient whose peripheral blood neutrophils and bone marrow precursors (beyond promyelocytes) contained multiple large azurophilic granules. There were also giant granules in eosinophils, basophils, melanocytes, renal tubules, thyroid, and neurones, but not lymphocytes or monocytes. His clinical course included recurrent (ultimately fatal) infections and severe neurologic impairment. Immunofluorescent staining with fluoroscein- and rhodamine-conjugated antisera to primary and secondary granule markers showed virtually all of the granulocyte granules and rare monocyte granules to be fusion products containing both markers. Electron microscopy showed the granules to be large peroxidase-containing lysosomes. Only rare normal primary and secondary granules were present. Superoxide generation in response to opsonized zymosan was 7.3 nmole/min/10(6) cells (control 8.9); but in response to phorbol myristate acetate, only 2.2 (control 9.4). Nitroblue tetrazolium slides showed 3+ dye reduction in response to opsonized zymosan by 90% of granulocytes (control 91%) and to phorbol myristate acetate by 22% (control 99%), with 71% producing only a minimal 1+ response. Cellular contents of myeloperoxidase and beta- glucuronidase were elevated, but the percent release during exocytic degranulation was equivalent to control. Ingestion of complement- opsonized Staphylococcus aureus and zymosan was also normal. Killing of Staphylococcus aureus was 60% at 90-min incubation (control 92%). Granulocyte cyclic adenosine monophosphate (AMP) content was 4 pmole/10(7) cells (control 3.1). In order to determine whether these characteristics derived from the cells' genetic program or their environment, the patient's bone marrow was grown in long-term culture. Granulocytes produced in vitro demonstrated the same morphology, same defect in activation of nitroblue tetrazolium reduction, and same normal cyclic AMP level as those harvested from peripheral blood. These studies describe a new disorder of granulocytes; the structural similarity to, but biochemical differences from, Chediak-Higashi disease indicate the probable heterogeneity of mechanisms for the same morphological abnormality.

Description: A 7-yr-old girl with self-limited pulmonary aspergillosis was found to have a defect in granulocyte superoxide production. Her cells produced superoxide at 3% of control rates in response to phorbol myristate acetate (PMA) and opsonized zymosan. Lag times for O-2 production were normal with PMA, opsonized zymosan, and concanavalin-A stimulation. Her granulocyte membranes depolarized in response to all of these stimuli. Superoxide produced by podosomes and a particulate fraction demonstrated an enzyme activity with a normal maximal velocity but a decreased affinity for NADPH. NADH-dependent superoxide production by particles was similar with patient and control material. The duration of superoxide production was prolonged in the patient's intact granulocytes and in the particulate fractions from her cells. Bacterial killing by the patient's granulocytes was initially low, but approached control values after 90 min of incubation. These results are explained by an enzyme activity that has a decreased affinity for its substrate and a decreased rate of inactivation. Family studies indicate an autosomal recessive mode of inheritance.