Biomedical subjects

H S Jacob

Publications and source records attributed to H S Jacob.

At least 55 records · Page 3Linked to original sources

PubMed1989

Thrombin-treated endothelium primes neutrophil functions: inhibition by platelet-activating factor receptor antagonists.

We have shown previously that fluid phase platelet-activating factor (PAF) can enhance or "prime" polymorphonuclear (PMN) responses to subsequent stimulation with agonists such as formyl-methionine-leucine-phenylalanine (FMLP). Since thrombin induces PAF production in endothelial cells, we tested whether this thrombin-provoked endothelial PAF primes responses of marginated PMNs. Monolayers of human umbilical vein endothelial cells were exposed to either thrombin (0.5-5.0 units/ml) or buffer for up to 5 min and then PMNs were layered on top of the endothelial cells. After a further 5 min incubation, the PMNs were stimulated with a suboptimal concentration of FMLP (10(-7) M), and their superoxide production, elastase release, adhesion to endothelium, and capacity to cause endothelial cell lysis and detachment were assessed. Thrombin pretreatment significantly enhanced each of these FMLP-stimulated neutrophil responses. The extent of this enhancement correlated with both the dose and duration of thrombin treatment of endothelial cells and also the duration of PMN incubation with thrombin-exposed endothelium. Evidence that the augmentation was due to endothelial-derived PAF was obtained as follows: (1) thrombin induced [3H]acetate incorporation into endothelial PAF (assayed in lipid extracts); (2) antithrombin III conjointly inhibited this [3H]acetate uptake and prevented the priming effect of thrombin-treated endothelium on PMN responses; and (3) the PAF receptor antagonist BN52021, when preincubated with PMNs, also effectively blocked the enhancement of PMN responses. We conclude that thrombin stimulation of endothelial cells initiates a sequence of events culminating in the production of PAF--a membrane phospholipid capable of priming marginated PMNs. We suggest that this coagulation-fostered endothelial/PMN interaction may underlie a paracrine response that may potentiate PMN-mediated endothelial injury during sepsis and other thrombin-generating disorders.

Endothelium, Vascular↗

PubMed1989

Herpes simplex virus inhibits endothelial cell attachment and migration to extracellular matrix proteins.

Herpes simplex virus (HSV) infection may be involved in various endothelial-injury syndromes, including vasculitis and atherosclerosis. In a previous study, it was reported that HSV-infected human umbilical endothelial cells are more vulnerable to detachment mediated by granulocyte-secreted proteases. To elucidate the molecular basis of this observation, the authors examined the interaction of infected endothelial cells with the purified basement membrane proteins, fibronectin, laminin, and type IV collagen. HSV-infected endothelial cells exhibited defects in their ability to adhere, spread, and migrate on all three matrix components. This defective adhesion could be partially overcome by increasing concentrations of fibronectin; in contrast, no abrogation of deficient binding occurs with increased levels of laminin or collagen type IV. This suggests that endothelial cells may use different surface constituents for binding to the three proteins and use multiple "receptors" for adhesion to the fibronectin molecule--"receptors" that are variably affected by HSV infection. The authors investigated this supposition by assaying adhesion of normal and infected endothelial cells to two non-overlapping cell-adhesion promoting fragments of fibronectin: 1) a 75 kd motility-promoting fragment which contains the arginyl-glycyl-aspartylserine (RGDS) adhesion sequence, and 2) a 33 kd carboxyl-terminal heparin binding fragment, which promotes cell adhesion by an RGDS-independent mechanism. Normal endothelial cells adhered and spread on both purified fragments. In contrast, while infected endothelial cells could adhere, albeit rather poorly, to high coating concentrations of the 75 kd fragment, these cells did not bind to the 33 kd heparin binding fragment of fibronectin at all. These results support the concept that endothelial cells adhere to multiple domains of fibronectin, and that HSV infection preferentially abrogates binding to the heparin-binding domain, while leaving relatively intact receptors for the RGDS-containing domain. In support, soluble RGDS significantly blocked fibronectin adhesion of infected, but not control, endothelial cells. It is concluded that HSV infection inhibits the interaction of endothelial cells with basement membrane proteins and weakens their tethering to substratum. This tethering is inadequate for proper cell spreading or movement to occur and may result in both excessive endothelial lift-off and impaired vascular repair in HSV infections.

Cell Adhesion↗

PubMed1989

Granulocyte-mediated injury to herpes simplex virus-infected human endothelium.

Some endothelial-injury syndromes, including atherosclerosis, may involve herpes simplex virus (HSV) infection. Examining the mechanism of injury, we found adherence of unstimulated granulocytes to HSV infected endothelium to be twice that to uninfected endothelium (34.8 +/- 1.1 versus 18.8 +/- 0.5%; mean +/- SEM; p less than 0.001) which further increased in the presence of anti-HSV antibodies. Enhanced adhesion was accompanied by excessive granulocyte-mediated lysis of 51Cr-labeled, HSV-infected endothelium (16.4 +/- 0.9%, HSV-infected versus 0.9 +/- 4.5% for uninfected endothelium; p less than 0.01). HSV infection also increased granulocyte-mediated endothelial cell detachment from its substratum (14.7 +/- 1.7% versus 3.3 +/- 0.3% for uninfected endothelium; p less than 0.001), which further increased (p less than 0.01) in the presence of immune complexes (IgG-sensitized erythrocytes). This suggests that neo-Fc receptors of infected endothelium bind IgG-coated particles, which, in turn, attract and stimulate granulocytes. In support, granulocyte-mediated detachment was not enhanced by immune complexes if endothelium was infected with a mutant HSV strain (E3/3) that does not produce glycoprotein E, the viral glycoprotein having Fc-receptor activity. Exaggerated endothelial detachment correlated with poor binding of infected endothelial cells to the substratum matrix protein, fibronectin. Resuspended, virus-infected endothelial cells bound significantly less well to tissue-culture wells coated with both low (p less than 0.001) and high (p less than 0.05) concentrations of fibronectin as compared with uninfected endothelial cells, a dichotomy further worsened in the presence of granulocyte-released elastase. We conclude that HSV-infected human endothelium is vulnerable to granulocyte-mediated injury by opposing alterations in its adhesive properties: its increased binding of granulocytes and its weakened tethering to matrix fibronectin, particularly when exposed to secreted granulocyte proteases, such as elastase.

Cell Adhesion↗

PubMed1989

Role of platelet activating factor in endotoxemic acute renal failure in the male rat.

We have developed a model of endotoxemic acute renal failure in the anesthetized male rat in which acute endotoxin infusion induces renal vasoconstriction and decreased glomerular filtration rate (GFR) in the absence of systemic hypotension. Because increased levels of platelet activating factor (PAF) have been observed in experimental models of endotoxemia, we pretreated rats with PAF receptor antagonist BN 52021 or SRI 63-675 before administering endotoxin. Compared with treatment with vehicle, treatment with BN 52021 led to significant preservation of RBF, GFR, and urine flow rate. Pretreatment with SRI 63-675 resulted in significant improvement in RBF while completely preventing the fall in GFR and urine flow rate. Intrarenal artery infusion of exogenous PAF (30 ng/kg/min) resulted in renal vasoconstriction, decreased GFR, and oliguria. These effects were also prevented by pretreatment with SRI 63-675. Thus, the adverse renal hemodynamic effects of endotoxemia were blunted or prevented by pretreatment with PAF receptor antagonists. We conclude that endogenously produced PAF is an important mediator of endotoxemic acute renal failure.

Acute Kidney Injury↗

PubMed1988

Mechanism of cultured endothelial injury induced by lymphokine-activated killer cells.

A new form of therapy of experimental tumors, utilizing lymphokine-activated killer (LAK) cells and high doses of interleukin 2, has recently been applied in the treatment of human neoplasms. Severe side effects, suggestive of a diffuse vascular injury of unknown etiology, have prevented a more widespread application of this form of therapy. We have investigated the etiology of this clinical capillary leak syndrome, using an in vitro model of endothelial injury. LAK cells, but not interleukin 2 itself, are cytotoxic to cultured human endothelial cells, and this cytotoxicity is time and dose dependent. This human endothelial cell cytotoxicity can be inhibited by depletion of extracellular Ca2+, inhibition of the effector cell microtubular system, and inhibitors of serine proteases, but is not inhibited in the presence of toxic oxygen radical scavengers. LAK cell-mediated endothelial cytotoxicity is far more potent than that exhibited by maximally stimulated polymorphonucleocytes. LAK cell-mediated injury of human endothelium may possibly be responsible for the capillary leak syndrome observed in patients treated with high doses of interleukin 2 and LAK cells.

Calcium↗

PubMed1988

Enhanced thrombin generation and platelet binding on herpes simplex virus-infected endothelium.

Atherosclerotic lesions have been reported to contain herpes simplex virus 1 (HSV-1) genomic material. This, and other previous evidence, suggests that latent viral infection may be an atherogenic trigger. Moreover, active HSV-1 lesions manifest marked fibrin deposition in microvessels. In this report we show that very early infection of human endothelial cells with HSV-1 appears to alter surface conformation as detected by merocyanine 540 staining. Concomitantly, the efficiency of prothrombinase complex assembly increases, resulting in a 2- to 3-fold accelerated rate of thrombin generation on the cell surface. Increased thrombin generation is probably doubly procoagulant, since we also demonstrate that thrombin-induced platelet accumulation on HSV-infected endothelium (50.7 +/- 9.3%) is increased compared to uninfected endothelium (9.5 +/- 2.1%; P less than 0.002). Associated with HSV infection, prostacyclin secretion in response to thrombin is diminished by a factor of 20, probably explaining the enhanced platelet attachment. We conclude that HSV infection shifts endothelial cell properties from anticoagulant to procoagulant, both by promoting prothrombinase complex formation and function and by increasing platelet binding, well before cell disruption takes place. Virus-induced changes in the endothelial plasma membrane and diminished prostacyclin secretion are suggested as the pathways for this pathophysiologic mechanism, which may be germane to atherosclerotic thrombosis as well as HSV-mediated tissue necrosis.

Arteriosclerosis↗

PubMed1988

Evidence for a role of iron-catalyzed oxidants in functional and metabolic stunning in the canine heart.

Brief (15-minute) coronary occlusion and subsequent reperfusion lead to prolonged functional and metabolic abnormalities (stunned myocardium). Previous work suggests that one factor responsible for this phenomenon is oxygen-derived free radicals. The formation of the highly reactive hydroxyl radical requires the presence of metal ions, most importantly iron. In the present study, the effect of the iron-chelator deferoxamine on the recovery of segment shortening (%SS) in the stunned myocardium was compared with a control group in barbital anesthetized dogs. Deferoxamine (500 mg intra-atrially) was administered 15 minutes prior to and throughout 15 minutes of coronary occlusion. %SS, regional myocardial blood flow, hemodynamics, and myocardial high-energy phosphates were measured. Areas at risk, collateral blood flow, and all hemodynamic parameters were similar between control and deferoxamine-treated animals. While deferoxamine did not prevent the loss of systolic wall function that occurred during ischemia, deferoxamine significantly improved the recovery of %SS at all times throughout reperfusion (3-hour %SS of pretreatment: control, 12 +/- 11; deferoxamine, 65 +/- 12), normalized endocardial ATP (percent of nonischemic area: control, 79 +/- 3%, deferoxamine, 93 +/- 6%), attenuated the reperfusion-induced rebound increase in phosphocreatine and prevented the increase in tissue edema at 3 hours after reperfusion. Thus, deferoxamine exhibited a cardioprotective action both metabolically and functionally in the stunned myocardium presumably by decreasing the redox cycling, and hence, the availability of catalytic iron for use in hydroxyl radical formation and for the initiation of lipid peroxidation. These data suggest a possible role for the hydroxyl radical as a mediator of postischemic abnormalities in reversibly injured tissue.

Animals↗

PubMed1988

Therapy with red blood cells decreases hyperoxic pulmonary injury.

Results of attempts to ameliorate hyperoxic pulmonary injury using novel systems for delivery of antioxidant enzymes are reviewed. Intratracheal insufflation of either liposome encapsulated superoxide dismutase or encapsulated catalase increased levels of enzyme activities in rat lung homogenates and prevented lethal effects of an atmosphere of oxygen. Intact erythrocytes placed in the tracheobronchial tree of rats also dramatically improved survival in hyperoxia. Recyclable glutathione appeared to be the constituent of erythrocytes, which was responsible for the protection. In rabbits, erythrocytes also protected from oxidant-mediated ischemic-reoxygenation lung injury. These studies suggest a possible role for erythrocytes as biologic packets of antioxidant enzymes.

Animals↗

PubMed1988

Platelet-activating factor primes neutrophil responses to agonists: role in promoting neutrophil-mediated endothelial damage.

During inflammation polymorphonuclear cells (PMNs) are exposed to agonistic stimuli including activated complement, kallikrein, arachidonic acid metabolites, monokines, and platelet-activating factor (PAF). We report that PAF not only directly activates PMNs but in miniscule quantities (10(-12) mol/L) "primes" them as well, that is, permits PMNs to respond to subsequent stimuli that would be otherwise ineffectual. PAF priming of responses including superoxide generation, elastase release, and aggregation is time dependent and is maximal within five minutes. PAF need not be present during the subsequent exhibition of PMN agonists, but priming is inhibited by cold and is also inhibited by the PAF receptor antagonists BN 52021, L-652, and kadsurenone. An intact PAF molecule is required because lyso-PAF and methoxy-PAF do not prime PMN responses. PAF priming is associated with both enhanced expression of the adhesive glycoprotein identified by OKM-1 antibody and an enhanced rise in intracellular calcium levels in response to the subsequent addition of agonists such as FMLP. PMNs primed with PAF and stimulated with either F-Met-Leu-Phe or phorbol esters are more effective in lysing and detaching cultured human endothelial cells--damage that can also be inhibited by the PAF antagonists. Because PAF is synthesized and exhibited on surfaces of endothelial cells perturbed by coagulation, we suggest that this lipid may potentiate otherwise trivial activators of marginated PMNs so that they become damaging to the PAF-synthesizing endothelium itself. If so, our studies suggest a possible therapeutic role for PAF inhibitors in excessive inflammatory states.

Benzofurans↗

PubMed1988

Measurement of intracellular calcium concentration in intact monolayers of human endothelial cells.

Intracellular calcium ([Ca++]i) plays an important role in signal transduction and cell activation. The measurement of [Ca++]i in intact monolayers of human umbilical vein endothelial cells with the fluorescent calcium-sensitive probe fura 2 has been evaluated. Monolayers provide a more physiologic cell preparation than suspensions and allow a greater variety of experimental manipulation. Basal [Ca++]i was 117 +/- 5 nmol/L, with a range from 40 to 280 nmol/L that was not affected by cell age (days of primary culture) or degree of confluence. Thrombin in concentrations of 0.005 to 5 NIH units/ml produced a dose-dependent increase in [Ca++]i up to a maximum of 1500 +/- 147 nmol/L; this increase was shown to depend in part on the concentration of extracellular calcium. The presence of antithrombin III at physiologic concentrations abolished responses to 0.5 NIH units/ml thrombin but had no effect on 5 NIH units/ml. The potential of this technique was demonstrated further by our ability to examine [Ca++]i responses in endothelial cells following infection with herpes simplex virus type 1, a virus implicated in vascular injury. After 18 hours' infection, the response to both thrombin and histamine was dramatically reduced despite a normal resting [Ca++]i. It is concluded that this method may be useful for detecting early and subtle changes in endothelial cell function under a variety of physiologic and pathologic conditions.

Antithrombins↗

PubMed1988

Excessive vulnerability of herpes-infected endothelium to lymphokine-activated lymphocytes: a possible role in lethal viral pneumonitis following bone marrow transplantation.

1. Lymphokine-activated killer cells are cytotoxic to human umbilical vein endothelial cells in vitro. 2. Cytotoxic efficiency of LAK cells correlates with serine esterase activity. 3. LAK cells generated from bone marrow transplant patients, as compared to normal volunteers, are significantly more cytotoxic for cultured endothelium, which correlates with their elevated serine esterase content and phenotypic NK-cell proportion. 4. Endothelium infected with herpes simplex virus for very brief periods (4 hr) becomes even more vulnerable to LAK cell-mediated injury. 5. Thus, bone marrow transplant patients harbor "primed" lymphocytes, highly liable to become lymphokine-activated killer cells. These cells have an NK phenotype, readily generate cytotoxic serine esterase activity, and manifest a proclivity to damage vascular endothelium--especially virally infected endothelium. We suggest this proclivity may underlie the severe endotheliitis and lethal pulmonary hemorrhage suffered by bone marrow transplant patients infected with herpesviruses.

Bone Marrow Transplantation↗

PubMed1988

Lymphocyte aggregation in response to adrenergic stimulation.

A nonanemic chronic lymphocytic leukemia patient with nearly 500,000 lymphocytes/microL underwent leukapheresis when she presented with CNS symptoms and retinal vascular engorgement. Respiratory distress developed during the cell separator run, which led us to ask whether the procedure could have changed the adhesive properties of her cells. C5a desarginine, N-f-Met-Leu-Phe, adenosine diphosphate, and collagen all failed to aggregate her lymphocytes in vitro, but arachidonic acid, excess free calcium, and 4 mumol/L epinephrine did aggregate the cells. Arachidonate-induced aggregation appeared to be a toxic phenomenon: the ED50 for aggregation was statistically indistinguishable from that for cytotoxicity, and aspirin only mildly blunted the response. In contrast, epinephrine-induced aggregation was not associated with lactic dehydrogenase release or the loss of trypan blue exclusion and was blunted by propranolol; radiopindolol-binding studies confirmed the presence of a beta-adrenergic receptor. There were approximately 3,000 receptors/cell, with no statistically significant difference between normal and chronic lymphocytic leukemia B cells or between B cells and T cells (separated by rosetting techniques). The Kd for the B cells' receptor, however, was less than that for T cells by a factor of ten (P less than .01). We conclude that B cells may aggregate when stimulated and that they--like T cells--have beta-adrenergic receptors. Adrenergically mediated changes in B cell adhesiveness may play a role in regulating lymphocyte traffic; in the rare patient with truly enormous B cell counts, we postulate that they may be an occasional cause of morbidity.

Adenosine Diphosphate↗

PubMed1988

Pulmonary hypertension and edema induced by platelet-activating factor in isolated, perfused rat lungs are blocked by BN52021.

The experimental intravenous administration of platelet activating factor (PAF) induces pulmonary hypertension and directly or indirectly increases capillary permeability. Selective PAF antagonists BN52021 and L652-731 have been shown to inhibit the action of PAF in vitro and in vivo. Using a unique isolated perfused rat lung model, we measured the effect of these PAF antagonists on PAF-induced pulmonary hypertension and edema. Isolated rat lungs were perfused with Krebs-Henseleit solution. The right and left pulmonary arteries were dissected so that they could be perfused selectively, permitting the use of one lung as an internal control for a specific pharmacologic challenge. Exposure of one lung to PAF induced an increase of perfusion pressure and wet/dry lung weight ratio in a dose-dependent manner compared with the control lung. The PAF antagonists attenuated the increase in perfusion pressure and wet/dry lung weight caused by PAF (0.75 micrograms) in a dose-dependent manner. In addition, prostaglandin F2 alpha induced an equivalent increase in pulmonary pressure without causing a similar increase in lung edema. PAF-induced pulmonary hypertension and the increase in wet/dry lung weight ratio appear to be PAF receptor-mediated processes, and the use of specific antagonists and this technique may be useful probes to determine the role of PAF in pathophysiologic states.

Animals↗

PubMed1987

Potentiated adherence of sickle erythrocytes to endothelium infected by virus.

Systemic viral infection is a known precipitant of vasocclusive crisis in sickle patients, but the mechanism underlying this clinical observation is unknown. In the present studies, human umbilical vein endothelial cells were infected with Herpes simplex virus type 1 (HSV) to model systemic viral disease. The already abnormal adherence of sickle erythrocytes to control endothelium is enhanced 1.8 +/- 0.4-fold to HSV-infected endothelium (P less than 0.001). This component of potentiated adherence is eliminated by maneuvers that block Fc receptors, it is prevented by tunicamycin, and it is not seen using a mutant HSV that is unable to express the Fc receptor glycoprotein. Thus, the incremental adherence seen here occurs due to expression of Fc receptor activity on HSV-infected endothelium and the consequent recognition of abnormal amounts of IgG on sickle erythrocytes. We conclude that systemic viral infection potentially can induce a novel mechanism for enhancement of erythrocyte adherence to endothelium and that this may increase the likelihood of vasocclusion during viral infection.

Anemia, Sickle Cell↗

PubMed1987

Granulocyte oxygen radicals as potential suppressors of hemopoiesis: potentiating roles of lactoferrin and elastase; inhibitory role of oxygen radical scavengers.

In vitro studies suggest intact endothelial cells and their released growth factors are required for optimal growth and differentiation of hematopoietic cells in culture. Conversely, processes that damage endothelium might, therefore, suppress hematopoiesis. We have studied mechanisms by which stimulated inflammatory cells, particularly granulocytes, damage endothelium and suggest these studies may provide new insights into the hematopoietic suppression of inflammatory diseases. We demonstrate that the granulocyte lysosomal constituent, lactoferrin, which has independently been shown to inhibit in-vitro hematopoiesis, may act by amplifying granulocyte-mediated toxic oxidant damage to endothelium. Its deleterious effects are twofold: 1) it releases iron that catalyses the Haber-Weiss reaction, thereby producing highly toxic hydroxyl radicals; and 2) its highly positive charge facilitates its absorption to target membranes that traffics oxygen-radical damage directly to endothelium. In addition, we demonstrate that another granulocyte lysosomal component, elastase, also perturbs endothelium--not so much by direct lytic effect, but by proteolysing matrix proteins that serve to attach endothelium to its substratum. Thus, elastase promotes endothelial lift-off. Plasma alpha-1-antiproteinase, a potent antielastase, should be protective, but is inactivated by the same granulocyte oxidants that directly lyse endothelial cells. However, antielastase activity can be preserved by antioxidants and a novel, innocuous one--methionine--is described. It is oxidized as a surrogate for the critical-site methionine of alpha-1-proteinase inhibitor, preserving in the process antielastase activity. Our results suggest that strategies to reduce production of inflammatory cell toxic oxygen radicals with reagents such as antilactoferrin antibody or iron chelators might be useful adjuncts in maintaining in vitro hematopoiesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidants↗

PubMed1987

Lymphokine activated killer (LAK) cell-mediated endothelial injury: a mechanism for capillary leak syndrome in patients treated with LAK cells and interleukin-2.

We have investigated the possible etiology of a severe clinical syndrome seen in cancer patients treated with a new form of cancer-specific therapy, referred to as adoptive immunotherapy. This syndrome, apparently characterized by diffuse capillary injury, results in the leakage of intravascular fluid into interstitial tissues, with consequent organ dysfunction that limits the applicability of this form of therapy. We have demonstrated, using an in vitro model of cultured human endothelial cell injury, that LAK cells--lymphocytes stimulated in vitro by IL-2--appear to be potent mediators of endothelial injury. This LAK cell-mediated endothelial cytotoxicity is both time and dose dependent and is not manifested by freshly isolated human lymphocytes or lymphocytes cultured for up to 7 days in the absence of IL-2. In contrast, significant LAK cell-mediated damage to human endothelial cells is observed in lymphocytes cultured for as little as 24 hr in media containing IL-2 and is still found in 14-day-old LAK cells. LAK cells appear to be far more potent than maximally stimulated PMNs in their cytolytic activity against endothelium. In contrast, no damage to cultured endothelial cells is provoked by very large doses of IL-2 alone. Levels of IL-2 that are 3-5 times greater than peak blood IL-2 levels, transiently present in patients following bolus IL-2 injections, fail completely to produce HEC cytotoxicity even during prolonged incubation. The mechanism by which LAK cells kill their targets appears to be analogous to that previously described for related cytolytic T lymphocytes and NK cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Capillaries↗

PubMed1987

Beta-adrenergic blockade: augmentation of neutrophil-mediated inflammation.

beta-Adrenergic blockade has been clinically associated with vascular occlusion. Because neutrophil activation, either alone or in concert with other blood cells, can induce vaso-occlusion by aggregation, leukoembolization, and inflammatory damage to vascular endothelium, we studied the effect of beta-adrenergic blockade on neutrophil activation in vitro and on microvascular integrity in vivo. beta-Adrenergic antagonists, propranolol and alprenolol, could induce dose-related and stereospecific activation of human neutrophils resulting in granulocyte aggregation and migration. Propranolol produced de novo aggregation and also enhanced responses to chemotaxins, N-formyl-methionyl-leucyl-phenylalanine and C5a. Lysosomal exocytosis was unaffected by beta blockers. In partial explanation of the enhancement of granulocyte activation by beta blockade, we observed that propranolol produced enhanced expression and affinity of granulocyte surface receptors for tritiated N-formyl-methionyl-leucyl-phenylalanine. This enhanced activation of human granulocytes by beta blockers was manifest in vivo as augmented inflammatory dermal edema. Enhanced granulocyte activation by beta blockade may induce microvascular disruption and subsequent tissue inflammation.

Alprenolol↗

PubMed1986

Lymphocyte populations and TAC-antigen in diffuse B-cell lymphomas.

Immune cell populations in 8 diffuse histology B-cell lymphomas were analysed in frozen tissue sections by indirect immunofluorescence to gain insight into their possible modulating influence in these tumors. Use of monoclonal antibodies to identify cellular and extracellular antigens combined with nuclear counterstaining allowed precise quantitation, localization and comparison of T- and B-lymphocyte populations. T lymphocytes clustered in non-random fashion. Areas of high T-lymphocyte density manifested higher T4:T8 ratios than locales with fewer T lymphocytes (p less than 0.05). Few cells had surface antigens (Leu 7, 73.1, OKM1) associated with natural killing. Cells strongly reactive with anti-TAC (Interleukin-2 receptor, associated with T-lymphocyte activation) were also T11 reactive and were usually helper (Leu 3) phenotype. In addition, B-lineage lymphoma cells in some tissues reacted with anti-TAC. The pattern of tumor cell reactivity with anti-TAC correlated with Rappaport histologic classification. These findings suggest that non-malignant T lymphocytes modulate B-lymphoma cell growth in situ, and that in some lymphomas the T-cell product IL-2 may be an important local growth factor.

Antibodies, Monoclonal↗