The relationship between CR3 deficiency and neutrophil actin assembly

Polymorphonuclear leukocytes (PMN) with a deficiency of the complement receptor type 3 (CR3) membrane glycoprotein family have impairments in the ability to adhere to surfaces as well as chemotactic and phagocytic defects, processes that require a functional contractile apparatus. PMN from the patient with neutrophil actin dysfunction (NAD) displayed similar functional characteristics to those with CR3 deficiency suggesting the two disorders may be the same disease. In order to evaluate the relationship between CR3 deficiency and actin assembly, actin filament assembly was measured in PMN from six previously reported homozygotes (two severe and four moderate CR3-deficient patients) as well as five heterozygotes for CR3 deficiency. PMN from all patients had normal unstimulated concentrations of F-actin and after exposure to the chemotactic peptide FMLP (5 x 10(-7) mol/L for 5 to 40 seconds at 25 degrees C) assembled actin normally. Pretreatment of normal PMN with concentrations of monoclonal anti-alpha CR3 antibody, capable of blocking PMN adherence, also failed to impair FMLP- induced actin filament assembly. CR3 glycoprotein expression was measured in PMNs from the mother, father, and older sister of the NAD patient (N Engl J Med 291:1093, 1974). Actin filament assembly was recently shown to be defective in PMNs from all three family members. The total concentrations of the alpha and beta CR3 subunits were below normal in PMN detergent extracts from the mother (25% of simultaneous controls) and older sister (56% of control). PMN surface expression of these two subunits was also found to be depressed (mother, 50%; older sister, 63% of control). These findings suggest these two NAD family members are heterozygote carriers for CR3 deficiency as well as NAD. Simultaneous studies of the father, however, demonstrated normal total concentrations of both the alpha and beta CR3 subunits (126% of controls) as well as normal surface expression of both subunits after phorbol myristate acetate stimulation and incubation at 37 degrees C (mean, 112% of controls) but slightly lower than normal levels after FMLP stimulation (mean, 83%). These findings indicate that CR3 deficiency generally is not associated with defective actin filament assembly and support the conclusion that NAD represents a unique kindred in which PMN actin function differs from previously reported genotypes of CR3 deficiency.     

Beta 2-integrin and L-selectin are obligatory receptors in neutrophil aggregation [see comments]

We have recently found that antibodies to L-selectin, the homing receptor on neutrophils, are as effective as those to beta 2-integrin at blocking formyl peptide-stimulated aggregation. Therefore, we investigated the requirements for expression of L-selectin and beta 2- integrin on adjacent cells during aggregation. Fluorescence flow cytometry allowed characterization of aggregates on the basis of size and color, as well as antibody binding to these two adhesive molecules. Formyl peptide-stimulated aggregate formation was measured for individual populations fluorescently labeled red (LDS-751) or green (CD44-FITC), and interpopulation red-green cell conjugates. Blocking either the beta 2-integrin or L-selectin adhesive epitope with monoclonal antibody on individual cell populations resulted in an approximately 50% reduction in two-color aggregation as compared with that in unblocked samples. Shedding the L-selectin on a cell population by preincubation with complexes of lipopolysaccharide and its plasma membrane binding protein also decreased aggregation to a control population by approximately 50%. We examined the aggregation of neutrophils from patients genetically deficient in beta 2-integrin and clinically leukocyte adhesion deficient (LAD). LAD adhesion to normal neutrophils was dependent on the expression of L-selectin on LAD cells and beta 2-integrin on normal cells. Thus, the minimum requirement for adhesion between two mixed populations of neutrophils was that one population expressed the beta 2-integrin and the other expressed the L- selectin adhesive epitope.     

Reevaluation of the effects of cytochalasins on steroidogenesis: studies on hamster granulosa cells

Cytochalasin B (CB), a drug that inhibits microfilament polymerization, as well as having other actions, such as inhibition of hexose transport, is reported to block tropic hormone-stimulated steroidogenesis. Cytochalasin D (CD) is a more effective inhibitor of microfilament polymerization than CB, but has no effect on hexose transport. We reevaluated the effects of these inhibitors of microfilament function on steroid formation by freshly isolated granulosa cells from PMSG-primed hamsters. These cells have been shown to produce increased progesterone in response to tropic stimuli using endogenous steroidogenic precursors during short term incubation. In addition, they use exogenous substrate in the form of hydroxysterols for steroid production. Thus, we could examine effects of CB and CD on the metabolism of exogenous and endogenous sterol substrates. To determine the specificity of actions of cytochalasins, the metabolism of other steroid intermediates was examined: the conversion of pregnenolone to progesterone and the conversion of androstenedione to estradiol. Also, the oxidation of [14C]octanoate to 14CO2, a process that occurs in the mitochondria, was examined. Both CB and CD (1-10 micrograms/ml) inhibited LH- and 8-bromo-cAMP-stimulated progesterone production. Neither cytochalasin inhibited the production of progesterone in response to pregnenolone, nor were endogenous pregnenolone levels increased in the presence of CB or CD. Treatment with CB, but not CD, resulted in decreased progesterone production in response to hydroxycholesterol and decreased the side-chain cleavage of [3H]25-hydroxycholesterol. CB completely blocked the conversion of androstenedione to estradiol, whereas the aromatase reaction was unaffected by CD. CB, but not CD, significantly reduced the oxidation of [14C]octanoate to 14CO2 by hamster granulosa cells. Our findings demonstrate significant differences in the effects of CB and CD on granulosa cells. CB, in contrast to CD, has wide-spread effects on granulosa cell function, interfering with the metabolism of hydroxycholesterols, the oxidation of fatty acids, and aromatization. The failure of CD to interfere with these same functions suggests a more specific action of CD on the steroidogenic machinery. We conclude that microfilaments play an important role in the process of steroid formation from endogenous substrate. CD appears to affect a post-cAMP step between the conversion of cholesterol to pregnenolone, presumably the delivery of endogenous cholesterol to the mitochondria.     

Combination chemotherapy (M-2) protocol (BCNU, cyclophosphamide, vincristine, melphalan, and prednisone) for Waldenstrom macroglobulinemia: preliminary report

Fourteen consecutively referred, symptomatic patients with Waldenstrom's macroglobulinemia (ages 52-87 yr) have been treated with the 5-drug M-2 protocol (BCNU, cyclophosphamide, vincristine, melphalan, and prednisone). Three patients were previously treated and 11 patients were untreated. The majority of patients were symptomatic from hyperviscosity. All patients have responded to therapy. Two patients have achieved complete remissions and 12 patients partial remissions to date. None of the patients with symptomatic hyperviscosity has required plasmapheresis since therapy with the M-2 has been initiated. Lymphadenopathy, hepatosplenomegaly, and anemia have also responded to treatment. Follow-up data are limited, with survival from initiation of therapy with the M-2 ranging from 2+ to 35% mo (median 17+ mo) 2+-40+ mo from time of diagnosis). Combination chemotherapy for Waldenstrom's macroglobulinemia with the M-2 protocol appears to increase the response rate in patients with symptomatic disease. Further survival analysis will be carried out.     

Auditory tasks for assessment of sensory function and affective prosody in schizophrenia

Schizophrenia patients exhibit impairments in auditory-based social cognition, indicated by deficits in detection of prosody, such as affective prosody and basic pitch perception. However, little is known about the psychometric properties of behavioral tests used to assess these functions. The goal of this paper is to characterize the properties of prosody and pitch perception tasks and to investigate whether they can be shortened. The pitch perception test evaluated is a tone-matching task developed by Javitt and colleagues (J-TMT). The prosody test evaluated is the auditory emotion recognition task developed by Juslin and Laukka (JL-AER). The sample includes 124 schizophrenia patients (SZ) and 131 healthy controls (HC). Properties, including facility and discrimination, of each item were assessed. Effects of item characteristics (e.g., emotion) were also evaluated. Shortened versions of the tests are proposed based on facility, discrimination, and/or ability of item characteristics to discriminate between patients and controls. Test–retest reliability is high for patients and controls for both the original and short forms of the J-TMT and JL-AER. Thus, the original as well as short forms of the J-TMT and JL-AER are suggested for inclusion in clinical trials of social cognitive and perceptual treatments. The development of short forms further increases the utility of these auditory tasks in clinical trials and clinical practice. The large SZ vs. HC differences reported here also highlight the profound nature of auditory deficits and a need for remediation.