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L Maródi

Publications and source records attributed to L Maródi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Flow cytometric assay of phagocytic activity of human neutrophils and monocytes in whole blood by neutral red uptake.

In a new, simple, and fast flow-cytometric method for the simultaneous measurement of phagocytic activity of human neutrophils and monocytes in whole blood, the fluorescence capability of the well-known vital stain, neutral red was used. The incubation of 0.5 ml heparinized human blood with the phagocytic stimulus of zymosan dose- and time-dependently increased the percentage and the red fluorescence intensity of both neutrophils (4.3 +/- 1.2 times) and monocytes (2.7 +/- 0.7 times) measured cytofluorimetrically. Decreased uptake of neutral red was observed in a patient with phagocytic disorder, based upon impaired engulfment of particles and production of reactive oxygen species. In a patient with chronic granulomatosis, however, no decrease of neutral red uptake was measured. Platelet activating factor and phorbol myristate acetate were also able to increase the uptake of neutral red by both monocytes and neutrophils, but to a lesser extent than zymosan. The advantage of this method is the possibility for the simultaneous measurement of phagocytic activities of monocytes and neutrophils stimulated by either particles or soluble activators. This method is suitable for the selective measurement of activation processes not related to the production of free radicals in the phagocytes.

Adolescent↗
PubMed1995

Chronic neutropenia and defect in superoxide generation of granulocytes in two patients: enhancement of bactericidal capacity and respiratory burst activity by treatment with recombinant human granulocyte colony-stimulating factor.

We have identified two unrelated girls with chronic neutropenia [absolute neutrophil counts (ANC) 10-870 and 10-940/microL in patients 1 and 2, respectively] and severe defect in superoxide anion generation by granulocytes. Formyl-methionyl-leucyl-phenylalanine-induced superoxide release was 1.2 +/- 0.9 and 1.9 +/- 1.9% (mean +/- SEM, n = 3) of normal controls', mean value in patients 1 and 2, respectively. However, granulocytes from both patients released a normal amount of superoxide upon stimulation with phorbol myristate acetate. Patient 2 exhibited characteristic features of Duane syndrome, a rare disorder of eye movement. Treatment of the patients with recombinant granulocyte colony-stimulating factor led to significant clinical improvements and reduction of infectious complications and to increases in the ANC, to 400-2100/microL in patient 1 and to 500-3000/microL in patient 2. Treatment with 5 micrograms/kg/d resulted in increased intracellular killing of opsonized Staphylococcus aureus by granulocytes and an enhancement of superoxide release upon stimulation with formyl-methionyl-leucyl-phenylalanine in both patients up to 11.1 +/- 6.0 and 13.5 +/- 7.0% (mean +/- SEM, n = 5) of normal controls', mean value in patient 1 and patient 2, respectively. These data suggested that recombinant human granulocyte colony-stimulating factor treatment enhanced resistance to bacterial infection by stimulation of superoxide generation and increasing the bactericidal capacity of peripheral blood granulocytes.

Blood Bactericidal Activity↗
PubMed1994

Candidacidal mechanisms in the human neonate. Impaired IFN-gamma activation of macrophages in newborn infants.

We studied the interaction between Candida albicans and mononuclear phagocytes derived from cord blood. In the presence of normal serum, the extent of phagocytosis and killing of candida by monocyte-derived macrophages was equivalent for newborns and adults. In the absence of serum both phagocytosis and killing by macrophages were reduced by half, but cord and adult cells were still equivalent. Mannosylated BSA and mannan inhibited ingestion of unopsonized candida by macrophages, suggesting a role for the mannose receptor. Exposure of cord and adult macrophages to IFN-gamma (10-500 U/ml) gave quantitatively different results in Candida killing, as well as in release of superoxide anion (O2-). Maximal increase in these functions with adult macrophages was achieved with 100 U/ml IFN-gamma. No enhancement with cord macrophages could be detected after treatment with 100 U/ml, and at 500 U/ml there was still significantly lower killing and O2- release compared with adult cells. Defective up-regulation of O2- release was also present in cord monocytes exposed to IFN-gamma on day 0. Studies of the surface expression of IFN-gamma receptors using a "nonblocking" mAb against the IFN-gamma receptor revealed a comparable number of receptors on cord and adult monocytes. When blocking Abs were used, however, there was a three times higher number of positive cells in cord monocytes. Specific binding of 125I-IFN-gamma to cord monocytes and macrophages was also higher compared with adult cells. These data suggest that neonatal macrophages have a normal capacity to ingest and kill both opsonized and unopsonized Candida but cannot be fully activated by IFN-gamma, a finding that could not be attributed to lower expression of IFN-gamma receptors on the neonatal cells.

Adult↗
PubMed1993

Enhancement of macrophage candidacidal activity by interferon-gamma. Increased phagocytosis, killing, and calcium signal mediated by a decreased number of mannose receptors.

In contrast to its macrophage-activating capacity, IFN-gamma downregulates expression of the macrophage mannose receptor (MMR), which mediates uptake of Candida and other microorganisms. We found that IFN-gamma induced a concentration-dependent increase in the capacity of human monocyte-derived macrophages to ingest and kill both opsonized and unopsonized Candida albicans and to release superoxide anion upon stimulation with Candida. Mannan or mannosylated albumin inhibited this activated uptake of unopsonized Candida, but glucan did not. Addition of mAb to complement receptor (CR) 3 did not inhibit ingestion; macrophages that lacked CR3 (leukocyte adhesion defect) showed normal upregulation of ingestion by IFN-gamma. The increased candidacidal activity of IFN-gamma-activated macrophages was associated with reduced expression of MMR by a mean of 79% and decreased pinocytic uptake of 125I-mannosylated BSA by 73%; K(uptake) of pinocytosis was not changed. Exposure of resident macrophages to unopsonized Candida did not elicit a transient increase in intracellular free Ca2+ ([Ca2+]i); macrophages activated by IFN-gamma expressed a brisk increase in [Ca2+]i on exposure to Candida. These data suggest that macrophage activation by IFN-gamma can enhance resistance to C. albicans infection in spite of downregulation of the MMR, perhaps through enhanced coupling of the MMR to microbicidal functions.

Calcium↗
PubMed1993

Enhancement of macrophage candidacidal activity by interferon-gamma.

In previous studies, we have reported that opsonized candida species are ingested by monocytes and monocyte-derived macrophages (MDM), but uptake of unopsonized candida is mediated only by MDM, primarily through the mannose receptor (MR). This study examines the effects of recombinant IFN-gamma on the uptake and killing of unopsonized C. albicans by MDM. We report here that MDM treated with IFN-gamma developed an increase in their capacity to ingest and kill unopsonized C. albicans and to release O2- upon stimulation with candida. Mannan (0.1 to 5 mg/ml) inhibited uptake of candida in a dose-dependent manner, but glucan (5 mg/ml) did not. These data suggest that mannose receptors may be involved in the increased phagocytosis and killing of unopsonized candida by human macrophages treated with IFN-gamma.

Adult↗
PubMed1991

[D-penicillamine does not affect the liver and kidney function in newborn infants nor the in vitro function of phagocytes].

D-penicillamine was introduced to treat neonatal hyperbilirubinaemia in 1973 and to prevent retinopathy of prematurity in 1980. In this study we investigated the renal and liver functions of neonates treated with DPA and the in vitro effect of the drug on superoxide anion generation and beta-glucuronidase release as well as on phagocytic and intracellular killing activation on human peripheral blood granulocytes. Our data concerning the renal and liver functions before and after 3 to 4 days DPA treatment reveal no pathological change during short-term administration in the neonatal period. Furthermore, none of the examined DPA concentrations influenced the phagocytic or killing activity of neutrophils.

Humans↗
PubMed1991

Mechanisms of host defense against Candida species. II. Biochemical basis for the killing of Candida by mononuclear phagocytes.

We studied the biochemical basis of candidacidal activity by comparing the killing of Candida albicans, a serious pathogen, and Candida parapsilosis, a low-grade pathogen, by human monocytes (Mo) and monocyte-derived macrophages. Mo killed C. parapsilosis significantly better than C. albicans. The two species triggered the respiratory burst and release of myeloperoxidase (MPO) and beta-glucuronidase in Mo to an equivalent extent. In contrast to Mo, macrophages killed both species to an equivalent extent. Mo exhibited a greater candida-stimulated respiratory burst than did monocyte-derived macrophages, and the respiratory burst was required for the killing of both species. C. parapsilosis was killed much more easily than C. albicans by exposure to low concentrations of hypochlorite or monochloramine, MPO-dependent oxidants released by Mo but not macrophages, which lack MPO. With six different Candida strains there was a significant correlation between killing by Mo and susceptibility to hypochlorite (r = 0.926) or monochloramine (r = 0.981) (p less than 0.01 for each). Species differences in resistance to killing by Mo may be related to differences in sensitivity to MPO-derived oxidants, and the ability of C. albicans to resist the effects of these oxidants may be a virulence factor associated with this species.

Candida↗
PubMed1991

Mechanisms of host defense against Candida species. I. Phagocytosis by monocytes and monocyte-derived macrophages.

We studied the biochemical basis of phagocytosis of Candida albicans, a serious pathogen, and Candida parapsilosis, which is rarely pathogenic, by human monocytes (Mo) and monocyte-derived macrophages (MDM). Optimal phagocytosis of both species by Mo required the presence of extracellular Ca2+ and opsonization through both the classic and alternative complement pathways. Serum-opsonized Candida were ingested equally by Mo and MDM; unopsonized Candida were phagocytosed only by macrophages, and uptake began slowly. This opsonin-independent phagocytosis required Ca2+ and could be blocked by yeast mannan or mannose-BSA conjugate, suggesting a role for the mannose receptor. Opsonized Candida elicited a vigorous increase in the concentration of [Ca2+]i in Mo and MDM, but no Ca2+ transient was detected in MDM stimulated with unopsonized Candida. Pretreatment of MDM with ionomycin to increase [Ca2+]i had no effect on phagocytosis of unopsonized Candida. Addition of 5 mM EGTA completely inhibited changes in [Ca2+]i in Mo and MDM, suggesting that the Ca2+ transient induced by opsonized Candida is due to an influx of extracellular Ca2+. Differences in pathogenicity between the two Candida species could not be explained by differences in any aspect of phagocytosis. Uptake mediated by the macrophage mannose receptor could play a role in clearance of Candida under opsonin-poor conditions.

Calcium↗
PubMed1990

Opsonic requirements and surface hydrophobicity of novobiocin-resistant, coagulase-negative staphylococci.

The opsonic requirement for phagocytosis and killing and cell-surface hydrophobicity of five strains of Staphylococcus saprophyticus isolated from clinical sources were studied. Phagocytosis and killing of bacteria by human granulocytes were measured in suspension. Bacterial aggregating cell-surface hydrophobicity was determined by salt aggregation, and the absorptive hydrophobicity was measured by hydrophobic interaction chromatography. All strains were well opsonised by pooled normal human serum 10%. Ingestion of these bacteria could be detected to a variable extent in the absence of extracellular opsonins; heat-inactivated serum 10% or intravenous IgG concentrate 1 mg/ml improved phagocytosis of all strains. Significantly increased rates of both the ingestion and killing of one of the five strains occurred in the presence of IgG or in the absence of opsonins, compared to those found with each of the other four. This particular strain had significantly stronger adsorptive surface hydrophobicity than the other four strains, and with all strains there was a correlation between hydrophobicity and phagocytosis by granulocytes in the absence of opsonins.

Coagulase↗
PubMed1990

Stimulation of the respiratory burst and promotion of bacterial killing in human granulocytes by intravenous immunoglobulin preparations.

We have examined the effect of two i.v. immunoglobulin preparations on the metabolic and functional activities of neutrophil granulocytes from the peripheral blood. Production of superoxide anion (O2-) by granulocytes was measured through superoxide dismutase inhibitable reduction of ferricytochrome C after incubation of cells for various times together with immunoglobulin (concentration ranging from 0.25 to 5.0 mg/ml). The results showed dose-dependent response of O2- production independent of the incubation time. Granulocytes containing ingested Staphylococcus aureus released a significantly (P less than 0.001) larger amount of O2- and killed a higher number (P less than 0.001) of viable bacteria in the presence of 5 mg/ml immunoglobulin than did cells incubated in the absence of extracellular i.v. immunoglobulin. These data raise the possibility that immunoglobulin concentrates for i.v. use may enhance the anti-bacterial activities of phagocytic cells through direct stimulation of the respiratory burst. Inflammatory reactions observed during i.v. immunoglobulin infusion in hypo- or agammaglobulinaemic patients may also be related to phagocytic cell activation.

Granulocytes↗
PubMed1990

Influence of D-penicillamine on metabolic and functional activities of neutrophil granulocytes.

Influence of D-Penicillamine (DPA) on metabolic and functional activities of neutrophil granulocytes was investigated in vitro by measuring superoxide anion production and beta-glucuronidase release as well as by determining phagocytic and intracellular killing activities of cells. Preincubation with DPA in the concentration range of 0.5-5.0 mM resulted in 28-53% increase in superoxide anion production by granulocytes stimulated with 10(-7) M FMLP. DPA in the same concentration range resulted in 145-371% rise in the FMLP-stimulated beta-glucuronidase release. However, uptake and subsequent killing of viable Staphylococcus aureus was not influenced by incubation of granulocytes with various concentrations of DPA (0.5-5.0 mM). From these results we conclude that DPA may influence the superoxide anion production and beta-glucuronidase release in granulocytes without altering the phagocytic and intracellular killing activities of these cells. We suppose that the unchanged antibacterial activity of neutrophil granulocytes is resulted by the two opposite DPA effects: acting extracellularly reduces free radical level while the direct membrane effect results in enhancing metabolic activity in granulocytes.

Blood Bactericidal Activity↗
PubMed1989

Opsonic activity in serum from septic infants treated with intravenous immunoglobulin.

Thirteen infants with staphylococcal sepsis and reduced opsonic activity received infusions of acid treated immunoglobulin together with antibiotics. Opsonic activity (using Staphylococcus aureus (type 42D) as the test organism), haemolytic activity of complement, and concentrations of complement C3 and IgG were measured in serum prepared before and after three days of treatment with immunoglobulin at a dose of 250-300 mg/kg/day. There was increased ingestion of S aureus by normal human granulocytes in the presence of fresh serum prepared after infusion of immunoglobulin and significantly increased opsonic activity of heat inactivated serum after treatment with immunoglobulin. The haemolytic activity of complement and concentrations of complement C3 were not influenced, and serum concentrations of IgG increased as the result of receiving a total of 800-900 mg/kg immunoglobulin over a period of three days. This study shows that administration of acid treated IgG to septic infants leads to functionally increased opsonisation.

Complement C3↗
PubMed1988

Immunoglobulin deficiency with increased immunoglobulin M in three siblings: effect of long-term immunoglobulin therapy.

Diagnosis of immunoglobulin deficiency with increased IgM (hyper-IgM syndrome) was made in three siblings (two girls and a boy) on the basis of history, physical findings, and laboratory data. The prominent clinical findings were recurrent viral and bacterial infections of the respiratory tract. The most severe infections affected the male patient, who died at the age of 8 years. Family history and the lack of clinical signs in the parents and relatives indicated no immunodeficiency which, together with the occurrence of the disease in both sexes, indicated an autosomal recessive inheritance. The two female patients (18 years old and 3 years old) have been treated with intravenous acid-treated immunoglobulin for 2 years, resulting in significant clinical improvement with respect to the frequency and severity of infections.

Adolescent↗
PubMed1987

Chemotactic activity of bronchoalveolar lavage fluid from children with recurrent obstructive bronchitis.

Boyden's method was used to assess the chemotactic activity of bronchoalveolar lavage (BAL) fluid samples from patients aged 1-6 ys with recurrent obstructive bronchitis when signs of chronic mucosal inflammation were observed bronchoscopically. BAL was performed to reveal features of this mucosal inflammation by analysing the lavagable cells and soluble factors. In comparison with the chemotactic effect of casein, the activity of the fluid proved to be high for polymorphonuclear leukocytes (PMNs), but significantly low for mononuclear cells. After treatment of antibodies to C3 and C5, the activity was decreased considerably, but not to a minimum. Presumably, other chemo-attractants (leukotriens, enzymes) can also be found in the lavage fluid beside macrophage- or serum-derived and locally activated complement components. A comparison of complement components/albumin ratios in BAL fluid with serum complement components/albumin ratios suggested a significant local production and/or concentration of these factors. On the basis of our results, an accumulation of PMNs could be expected in the differential cell count, but an increased influx of macrophages was detected. Other amplifying or inhibitor systems may play an important role in the accumulation of PMNs in vivo.

Bronchitis↗