Modulation of leukotriene generation from human polymorphonuclear granulocytes by polychlorinated biphenyls (PCB)

Various isomers of polychlorinated biphenyls (PCB) were studied to induce and modulate the generation of lipo-oxygenase products (leukotrienes) from human polymorphonuclear granulocytes (PMN) under non-cytotoxic conditions. Stimulation of human PMN with PCB did not induce leukotriene generation by themselves, but modulated the subsequent leukotriene formation when opsonized zymosan or sodium fluoride (NaF) were applied as stimuli. The simultaneous addition of PMN with opsonized zymosan and PCB, especially 3,3',4,4'-TCB, led to an increased generation of leukotrienes compared to the control. 3,3',4,4'-TCB exceeded the activity of the remainder PCB in a dose-dependent manner and also induced a chemiluminescence response from PMN. The simultaneous incubation of PMN with NaF and 3,3'-DCB,3,3',4,4'-TCB and 2,2',3,3'-TCB showed an inhibitory effect on leukotriene generation unlike NaF stimulation in the absence of PCB. Incubation of PMN with PCB had no significant effect on leukotriene generation induced by the Ca-ionophore (5 microM). Our data show a direct relationship between the extent of PMN stimulation and the chloro-substitution pattern of the PCB in combination with the different stimuli.

A radioimmunoassay for the determination of insulins from several animal species, insulin derivatives and insulin precursors in both their native and denatured state

Antibodies were raised against the carboxy terminus of the insulin A chain in sheep, goat and rabbit using as antigen the synthetic octapeptide YQLENYCN conjugated to bovine serum albumin (BSA). All of the antisera obtained cross-reacted with molecules containing this peptide sequence. Using these antibodies, we developed a radioimmunoassay that could detect the insulin A chain itself, both denatured and natural mammalian and avian insulins, as well as proinsulins and insulin fusion proteins from microorganisms.

G protein activation and mediator release from human neutrophils and platelets after stimulation with sodium fluoride and receptor-mediated stimuli

Human polymorphonuclear granulocytes (PMN) and platelets were pre-activated with a receptor-mediated stimulus [formyl-methionyl-leucyl-phenylalanine (FMLP) or thrombin, respectively] and subsequently incubated with sodium fluoride (NaF). We investigated various cell responses, such as chemiluminescence by PMN, platelet aggregation and the release of lipid mediators [i.e. leukotriene B4 (LTB4) and its omega-oxidation products from neutrophils and 12-hydroxy-eicosatetraenoic acid (12-HETE) from platelets]. As a marker of G protein involvement, the binding of [3H]guanylylimidodiphosphate (Gpp (NH) p) to the membrane fractions of stimulated cells was determined. PMN pre-stimulated with FMLP showed a synergistically enhanced generation of leukotrienes returning to control values with the time of preincubation. Platelets preliminary treated with thrombin followed by incubation with NaF resulted in a sub-additive and time-independent mediator generation. Neither chemiluminescence by PMN nor platelet aggregation showed a similar pattern compared to the mediator release: PMN preincubated with FMLP followed by NaF resulted in a second chemiluminescence response; the aggregation of platelets which were preincubated with thrombin was partially inhibited by the addition of NaF. Membrane fractions isolated from FMLP-pre-stimulated neutrophils showed a pattern in [3H]Gpp (NH) p-binding capacity that was comparable to the respective leukotriene release. With thrombin-prestimulated platelets, no similarities between Gpp (NH) p binding, aggregation or 12-HETE generation were observed. The sequential activation of different cell populations using the same kind of stimulation lead to different cell responses, indicating the diversity of G proteins and their control mechanisms.

Staphylococcus aureus modifies the cytokine-induced immunoglobulin synthesis and CD23 expression in patients with atopic dermatitis

The influence of Staphylococcus aureus on peripheral blood lymphocytes (PBL) of patients with atopic dermatitis (AD) was analysed. The parameters studied were spontaneous and interleukin-inducible immunoglobulin (IgA, IgE, IgG) synthesis, as well as CD23 expression. Various heat-killed, clinical isolates of S. aureus were analysed. PBL from non-atopic donors served as controls. The time-course of co-cultured PBL with S. aureus showed a dose-dependent increase in immunoglobulin (Ig) synthesis from PBL of normal donors, whereas the Ig synthesis of atopic cells was significantly depressed. Additional stimulation with interleukin-4 (IL-4) also led to a pronounced suppression of the IgE and IgA synthesis in normal donor cells, while the effect of S. aureus on PBL of atopic donors was not markedly affected by IL-4. Transwell cultures of bacteria separated from PBL by a semi-permeable membrane induced stimulation of IgA and IgE synthesis in patients with AD. The Ig synthesis in the control group was not altered. Co-stimulation of S. aureus and IL-4 in this system led to a suppression of IgA with cells of both atopic and normal donors. IgE synthesis from atopic PBL was significantly stimulated. The CD23 expression of atopic PBL was increased by S. aureus and IL-4. Our data indicate that S. aureus may modulate the cytokine-dependent humoral immunity in patients with AD and that chronic colonization of the skin may be responsible for allergic skin reactions in AD.

Interleukin-3, interleukin-8, FMLP and C5a enhance the release of leukotrienes from neutrophils of patients with atopic dermatitis

The influence of the receptor-specific stimuli interleukin-3 (IL-3), interleukin-8 (IL-8), C5a and formyl-methionyl-leucyl-phenylalanine (FMLP) on the generation of arachidonic acid-derived inflammatory mediators from neutrophils (PMN) has been studied in patients with atopic dermatitis (AD) as well as in healthy, non-atopic volunteers. The release of leukotriene (LT)B4, the omega-oxidation products 20-COOH- and 20-OH-LTB4 and the cysteinyleukotriene LTC4 were measured by reverse-phase HPLC and radioimmunoassay. The incubation of neutrophils with these stimuli led to a significantly higher release of LTB4 and LTC4 in the AD group. The spontaneous leukotriene generation of PMN from patients with AD was on average threefold higher compared to the control group. C5a stimulated the release of LTB4 and its metabolites from atopic cells up to 9 ng in contrast to low amounts from non-atopic cells. Furthermore, FMLP distinctly enhanced the leukotriene release of neutrophils from patients with AD compared to unstimulated cells and to cells of normal donors. IL-3 and IL-8 also significantly stimulated the generation of LTB4 and LTC4 of PMN from atopic patients. Our data emphasize that neutrophils may play an important role in the pathogenesis of AD by an increased responsiveness to receptor-specific stimuli and further suggest that IL-3 and IL-8 influence the acute and chronic inflammatory reactions in patients with AD.

[Microbial pathogenicity factors and host defense mechanisms--parameters of post-traumatic infections]

The clinical features of posttraumatic infections are due to the interactions between microbial pathogenicity factors and the host defense. The virulence mechanisms of microorganisms include the adherence, chemotaxis, invasion, resistance, and production of toxins. In addition, the humoral and cellular components of the immune system are impaired in trauma patients. The influence of pathogenic microorganisms on immune effector cells results in the release of various inflammatory mediators which participate in the protective host response to infection but induce local and systemic damage provided they are excessively produced and/or ineffectively metabolized.

12-Hydroxyeicosatetraenoic acid (12-HETE) induces heat shock proteins in human leukocytes

12-Hydroxyeicosatetraenoic acid (12-HETE) induces the expression of individual heat shock proteins in human leukocytes (lymphocytes, monocytes, basophil granulocytes; LMBs). Metabolic radiolabeling of LMBs revealed that exogenous 12-HETE (20 ng) led to the expression of a 65- and 83kDa protein. Immunoreactivity towards the 65kDa protein was commonly detected. In contrast, after heat shock treatment and predominantly after incubation with 12-HETE significant immunoreactivity (anti-hsp72) was detected in the lower molecular weight range whereas immunoreactivity (anti-hsp90, AC88) was only observed after heat shock treatment of LMBs.

In vitro effects of polychlorinated biphenyls on human platelets

Incubation of human platelets with polychlorinated biphenyls (PCB) induced and modulated cellular responses to a different degree. 3,3',4,4'-tetrachlorobiphenyl (TCB) was a more potent inducer of platelet aggregation, serotonin release and 12-HETE generation compared to the other PCB [2,2',3,3'-TCB,3,3'-dichlorobiphenyl (DCB),2,2',4,5,5'-pentachlorobiphenyl (PCB)]. 3,3',4,4'-TCB showed synergistic effects, in combination with other PCB, such as an enhanced formation of 12-HETE, when 3,3'-DCB and 2,2',3,3'-TCB were applied simultaneously. The combined incubation of platelets with PCB and sodium fluoride (NaF), an activator of G-proteins, resulted in synergistic 12-HETE generation compared to stimulation with NaF or PCB alone. Furthermore, when platelets were incubated with the PCB the enzymatic steps controlling the metabolism of the platelet-activating factor (PAF) were modulated. A direct relationship between the extent of platelet activation and the chloro-substitution pattern of PCB exists.

Differential regulation of T- and B-lymphocyte activation in severely burned patients

We studied the in vitro expression and regulation of the CD23 and CD25 (Tac) surface antigens by peripheral blood lymphocytes (PBL) from severely burned patients (burn injuries ranging from 25% to 72% TBSA) in order to evaluate T- and B-lymphocyte activation processes after thermal trauma. The spontaneous and cytokine (IL-4, IL-2)-induced expression of CD23 which represents a B-cell activation marker was significantly reduced during the second to fifth week postburn when compared to healthy donors. In contrast, CD25, which is expressed on activated T cells, showed a marked increase both spontaneously, indicating an in vivo activation, and after stimulation with IL-2 or PHA. Concomitantly, T-cell proliferation induced by PHA or Con A was suppressed. However, the number of T and B cells remained unchanged. The data demonstrate the impairment of early events in the lymphocyte program in severely burned patients. The activation of B cells is downregulated, since they become refractory to external helper signals. In addition, T cells are highly activated but fail to proceed to proliferation in response to mitogenic stimuli.

Characterization of allergenic components of rye and wheat flour (Secale, Triticum vulgaris) by western blot with sera of bakers: their effects on CD23 expression

The allergenic components of water-soluble rye flour extract were studied by immunoblotting. Sera from 100 bakers were analyzed for their IgG, IgG4 and IgE binding pattern. Two allergens with molecular weights of 35 and 14 kD were detected. Previously, the major allergens of wheat flour extract were identified. The wheat flour components at a MW of 15/17 kD and the rye flour component at a MW of 14 kD were purified and isolated. The modulation of the low affinity receptor for IgE (Fc epsilon RII/CD23) on monocytes by separated allergenic components was studied. Depending on the allergen concentration the CD23 expression on isolated cells increased after stimulation with the rye flour component (MW 14 kD). The combined addition of the rye flour component (14 kD) with IL-4 induced a significant CD23 expression as compared to IL-4 alone.

Modulation of leukotriene formation by cellular composition and exogenous leukotriene A4

We investigated the interactions of exogenous leukotriene A4 (LTA4) with isolated cells in the presence or absence of cellular stimuli. The majority of isolated cells are able to transform exogenous LTA4 into LTB4 as well as LTC4. In eosinophils, LTA4 induced 15-hydroxy-eicosatetranoic acid formation and was converted into LTB4. The Ca-ionophore-induced generation of LTB4 from polymorphonuclear leukocytes or from the cell fraction containing lymphocytes, monocytes and basophils was significantly suppressed with LTA4 while the formation of LTC4 was increased. Conversely, the Na-fluoride- and fMLP-induced generation of LTB4 was significantly increased. Our results suggest that the stimulus and the cellular composition determine the pattern of the generated inflammatory mediators.

Basic mechanisms of cellular priming and release of inflammatory mediators

Simultaneous stimulation of human neutrophils (PMN) with the receptor-mediated activator formyl-met-leu-phe (FMLP) and the G protein activator sodium fluoride (NaF) resulted in the synergistic generation of leukotrienes. Activation of human platelets with thrombin and NaF showed an additive formation of 12-HETE. This enhancement in lipid mediator generation correlated with a time-dependent synergism in G protein activation after sequential stimulation of intact cells with FMLP and NaF or thrombin and NaF, respectively. In addition, polymerization of actin, an early event in cell activation, was enhanced after incubation with cytokines and FMLP.

Isolation and characterization of a 60-kDa IgE-binding component derived from sera of atopic patients (atopic dermatitis)

The low-affinity receptor for IgE (Fc epsilon RII, CD23) and the related soluble IgE-binding factors (IgE-BF; sCD23) play an important role in IgE regulation. Sera of patients suffering from atopic dermatitis (AD) were reported to contain an IgE-binding component with a molecular weight of 60 kD. The aim of our studies was the isolation and characterization of the 60 kD component. Sera of patients with AD were fractionated by ammonium sulfate precipitation (10-90%). The fractions were analyzed with regard to their IgE and their IgE-BF contents. Furthermore, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and subsequent autoradiography with 125I-labeled human IgE (PS) was performed to detect IgE-binding activity. The major amount of IgE as well as IgE-BF was obtained within the 30-50% ammonium sulfate precipitation. In addition, IgE-binding activity was precipitated at 60% saturation. Separation by gel filtration under physiological conditions indicated IgE-BF with molecular weight of greater than 100, 60, 25 and 15 kD. Rechromatography of the greater than 100-kD fraction led to IgE-binding activity with a molecular weight of 60 kD which is not present within normal sera. The data demonstrate that the 60-kD component is partially bound to serum IgE. One may suggest that the complex is involved in the induction and persistence of allergic disorders.

Microbial pathogenicity and host defense mechanisms--crucial parameters of posttraumatic infections

Posttraumatic and postoperative infections which may be either localized or turn into sepsis are a major cause of morbidity and mortality in surgical patients. They derive from the imbalance between microbial pathogenicity factors and the host defense system. The virulence mechanisms include adhesion, chemotaxis, invasion, resistance, and production of toxins. In addition, local and/or systemic immune functions in these patients are altered. Unspecific as well as specific cellular and humoral defense mechanisms are affected. The interaction of defined microbial pathogenicity factors with immune effector cells results in the activation of a variety of inflammatory mediators; they are a prerequisite for protective immunity but also induce local or systemic damage in the host when they occur in excessive amounts or when their metabolism is inadequately controlled. The analysis of the pathophysiological events during infection in surgical patients by taking advantage of modern molecular and cell biological methods may contribute to the development of novel therapeutic strategies.

Regulation of CD23 expression, soluble CD23 release and immunoglobulin synthesis of peripheral blood lymphocytes by glucocorticoids

Evidence was obtained that glucocorticoids are capable of modulating the CD23 expression and soluble(s) CD23 release of peripheral blood lymphocytes (PBL). We demonstrate that interleukin-2 (IL-2)- and IL-4-induced CD23 expression are susceptible to glucocorticoids to a different degree. Prednisolone suppressed the spontaneous and IL-2-induced CD23 expression on PBL of healthy donors. The IL-4-induced CD23 expression was influenced much less by prednisolone, but the expression kinetics was altered. The modulation of the expression kinetics appears to be due to a priming effect of prednisolone. Differences were also apparent when the susceptibility of PBL from healthy and atopic donors towards the effect of prednisolone on the IL-4-induced CD23 expression was studied. Preactivation of PBL with Staphylococcus aureus strain Cowan I abolished the differences. Prednisolone also suppressed the sCD23 release from unstimulated and IL-2- or IL-4-stimulated PBL and enhanced the immunoglobulin (E,G,A,M) synthesis of PBL. This enhancement appears to be due to a priming effect, since pre-stimulation of PBL with prednisolone was sufficient to enhance the immunoglobulin synthesis. The IL-4-induced IgE synthesis of PBL with or without spontaneous in vitro IgE synthesis was synergistically enhanced by glucocorticoids.

Metabolism of platelet activating factor (PAF) and lyso-PAF in polymorphonuclear granulocytes from severely burned patients

We studied the metabolism of 3H-platelet activating factor (PAF) and lyso-PAF in human polymorphonuclear granulocytes (PMN) from severely burned patients (n = 6) on days 1, 5, 9, 15, and 25 post-trauma. All patients suffered from a severe burn trauma of more than 30% total body surface area. Stimulation of PMN in healthy donors (n = 10) with the Ca-ionophore resulted in the conversion of 3H-lyso-PAF into PAF (18 +/- 2% of total radioactivity) and alkyl-acyl-glycero-phosphorylcholine (alkyl-acyl-GPC, 50 +/- 6%). In burned patients a significantly reduced formation of 3H-PAF was observed between days 1 and 15 post-trauma (day 9: 1 +/- 1%, p less than 0.0001). This pattern was normalized again in patients (n = 5) who survived the trauma after septic periods and was observed during the second week post-trauma. In one patient who succumbed to his injuries a sustained inhibition of PAF formation was observed up to his death. The decreased formation of PAF correlated weakly with the appearance of immature granulocytes within the analyzed cell fraction (ratio of immature cells versus PAF-formation, r = -0.55, p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Basophil releasability in severely burned patients

Thermal injury is known to induce dysregulation of the immune system; however, the precise mechanisms have to be clarified. We investigated the histamine release of basophil granulocytes from severely burned patients (n = 12) after stimulation with anti-IgE or the Ca-ionophore A 23187, respectively. The anti-IgE-induced basophil histamine release of all patients was reduced in comparison to healthy donors beginning at day one postburn (p.b.) (5.0 +/- 2.3% vs. 30.5 +/-3.4%), while the Ca-ionophore-induced release was not decreased before day two p.b. Basophils of patients who finally succumbed to their injuries showed poor responsiveness (to zero levels) over the total time. In contrast, the basophil releasability of surviving patients returned to nearly normal levels (fifth to seventh week p.b.). Already in the second week p.b. there was a significant difference in histamine release between survivors and nonsurvivors [e.g., days 6-9 p.b.: 23.7 +/- 4.0 vs. 6.9 +/- 2.7 (p less than 0.005) after Ca-ionophore stimulation]. The altered basophil histamine release was neither due to a diminished dose- or a delayed time-response to the stimuli nor due to differences in the basophil counts or the cellular histamine content. Our data indicate that the decrease of the basophil releasability, which may be secondary to altered signal transduction pathways in severely burned patients correlates with the clinical outcome.

Studies on B-lymphocyte dysfunctions in severely burned patients

We studied in vitro functional parameters of peripheral blood B-lymphocytes from severely burned patients (n = 10; burn injuries ranging from 25 to 72% TBSA). While the number of B-cells remained unchanged, B-cell proliferation induced by Staphylococcus aureus strain Cowan I (SAC) was normal or even enhanced at early and late phases postburn, but showed a marked suppression during the second to fourth week. A similar pattern was observed for the pokeweed mitogen (PWM)- or SAC-stimulated synthesis of immunoglobulin M (IgM), whereas IgG production was decreased over the whole postburn period monitored. Cytokine (interleukin 4)-induced B-cell activation as indicated by the expression of the CD23 surface antigen was impaired throughout the second to fifth week. In parallel, the release of the proteolytic cleavage product sCD23 which represents a B-cell growth and differentiation factor was reduced. Our data provide evidence that activation, proliferation, and differentiation processes of B-lymphocytes are impaired in severely burned patients, which may contribute to their enhanced susceptibility to infection and sepsis.