Edward J. Goetzl

Inhibition by somatostatin of the proliferation of T-lymphocytes and Molt-4 lymphoblasts

The proliferation of Molt-4 lymphoblasts and phytohemagglutinin-stimulated human T lymphocytes in vitro was inhibited significantly by 10(-12) to 10(-10) M to 10(-13) to 10(-9) M somatostatin, as assessed by the uptake of [3H]thymidine and [3H]leucine, respectively. The inhibitory effect of somatostatin was not attributable to cytotoxicity and was associated with a mean degradation of 52 and over 95% of immunoreactive somatostatin, respectively, after 3 and 24 hr of incubation at 37 degrees C. The specific suppression of Molt-4 lymphoblasts and T lymphocytes by somatostatin represents a distinct mechanism for the specific regulation of immunological responses by neuropeptides of the peripheral nervous system and gastrointestinal tract.

Alterations in human leukocyte function induced by ingestion of eicosapentaenoic acid

Two groups of six adults with persistent asthma, who were identical clinically, received 0.1 or 4 g of purified eicosapentaenoic acid ethyl ester (EPA) daily for 8 weeks. Both doses increased significantly the generation of leukotriene B5 (LTB5) from EPA by polymorphonuclear (PMN) and mononuclear leukocytes, while only the high dose decreased leukocyte arachidonic acid (AA) and the generation of LTB4 and prostaglandin E2 from AA. Only the high dose led to inhibition of PMN leukocyte chemotaxis to multiple stimuli by a mean of 57–70% (P<0.01), without altering monocyte chemotaxis, the production of plateletactivating factor by mononuclear leukocytes, or the IgE-dependent release of histamine from basophils. Both doses of EPA increased the responses of T lymphocytes to phytohemagglutinin by a mean of 73% or more (P<0.01) without modifying the numbers of helper and suppressor T lymphocytes. EPA affects the functions of several types of leukocytes critical to inflammation and immunity.

Elevated concentrations of leukotriene D4 in pulmonary edema fluid of patients with the adult respiratory distress syndrome.

The possible contribution of metabolites of arachidonic acid to the increased permeability of the alveolar-capillary barrier in the adult respiratory distress syndrome was examined by quantifying the pulmonary edema fluid concentrations of lipoxygenase and cyclooxygenase products. The concentration of leukotriene D4 in pulmonary edema fluid of 10 patients with the adult respiratory distress syndrome (18.5±6.8 pmol/ml; mean±SD), assessed by specific radioimmunoassay after isolation of the mediator, was significantly higher (P<0.001) than that of five patients with cardiogenic pulmonary edema (4.4±1.1 pmol/ml). The concentrations of leukotrienes B4 and C4, prostaglandin E2, and thromboxane B2 in edema fluid were not significantly different in the adult respiratory distress syndrome patients than in the other subjects with pulmonary edema. The edema fluid concentration of leukotriene D4 correlated with the ratio of edema fluid to plasma concentrations of albumin (r=0.64). Leukotriene D4 thus may contribute to the permeability defect which allows an accumulation of proteinrich alveolar fluid in the adult respiratory distress syndrome.

Selective localization of vasoactive intestinal peptide and substance P in human eosinophils.

Extracts of purified human eosinophils had a mean concentration of 72 fmol of immunoreactive vasoactive intestinal peptide and 21 fmol of substance P per 10(7) eosinophils, that were significantly higher than the content of immunoreactivity of the same neuropeptides in neutrophils, mononuclear leukocytes, and platelets. In contrast, the lower concentrations of calcitonin gene-related peptide and somatostatin were similar in extracts of all leukocytes. Chromatography of the peptides from eosinophils confirmed their identity with vasoactive intestinal peptide and substance P from neuroendocrine sources. Stores of some neuropeptides may endow eosinophils with unique roles in host defense and hypersensitivity reactions.

Neuropeptide Modulation of Leukocyte Function

Neuropeptides released from peripheral nerve endings in mammals, including substance P (SP), somatostatin (SOM), vasoactive intestinal peptide (VIP), and calcitonin gene-related peptide (CGRP), are potent mediators of smooth muscle contraction and relaxation, vasodilatation, secretion by exocrine glands, and leukocyte function. The potent effects of these peptides on mast cells, lymphocytes, and other types of leukocytes and the generation by leukocytes of neuropeptide-like factors suggest the possibility of important bidirectional modulatory influences between the nervous system and leukocytes in immunologic and inflammatory responses.

Alveolar macrophage lipoxygenase products of arachidonic acid: Isolation and recognition as the predominant constituents of the neutrophil chemotactic activity elaborated by alveolar macrophages

Abstract This study examines the contribution of the lipoxygenase products of arachidonic acid, termed hydroxy-eicosatetraenoic acids or HETEs, to the neutrophil chemotactic activity elaborated by rabbit alveolar macrophages. The predominant neutrophil chemotactic activity released by phagocytosing alveolar macrophages exhibits a molecular weight of 300–800, as assessed by Sephadex G25 filtration, and cochromatographs with defined HETE standards on silica gel H thin-layer plates. The chemotactic factors generated by the alveolar macrophages were identified by gas chromatography and mass spectroscopy as 5-HETE and 11-HETE. The quantities of 5-HETE and 11-HETE released from alveolar macrophages at 1 and 4 hr were increased up to five-fold by phagocytosis. Incubation of the alveolar macrophages with the lipoxygenase inhibitor 5,8,11,14-eicosatetraynoic acid prior to phagocytosis eliminated completely the stimulation of the generation of both the HETEs and the neutrophil chemotactic activity. The neutrophil chemotactic activity produced by phagocytosing alveolar macrophages thus is attributable largely to 5-HETE and 11-HETE.

Preferential human eosinophil chemotactic activity of the platelet-activating factor (PAF) 1-0-hexadecyl-2-acetyl-sn-glyceryl-3-phosphocholine (AGEPC)

The chemotactic responses of human blood neutrophils and of eosinophils of two different densities, which were resolved by centrifugation on gradients of polyvinylpyrrolidone-coated silica gel (Percoll), were quantified in modified Boyden micropore filter chambers using highly purified synthetic 1-0-hexadecyl-2-acetyl-sn-glyceryl-3-phosphocholine (AGEPC or PAFacether) and leukotriene B4 (LTB4) as stimuli. Maximal chemotactic responses of the densest eosinophils, less dense eosinophils, and neutrophils were evoked by 1 nM, 100 nM, and 1 µM PAFacether, respectively, and by 30–100, 30–100, and 10 nM LTB4. The magnitude of the maximal chemotactic response to PAFacether of the densest eosinophils was significantly greater than that of neutrophils. The eosinophil responses to PAFacether were chemotactic, as distinguished from chemokinetic, and were not influenced by the percentage of contaminating neutrophils. PAFacether is a more potent chemotactic factor for eosinophils than neutrophils and selectively attracts the densest population of human blood eosinophils.

A sensitive and specific radioimmunoassay for leukotriene C4.

A sensitive and specific radioimmunoassay suitable for direct measurement of leukotrine C4 was developed. Acetylated leukotriene C4 was coupled to polyamino bovine serum albumin using 1‐ethyl‐3‐(3‐dimethylamino‐propyl) carbodiimide hydrochloride as coupling agent. The conjugate in complete or incomplete Freunds adjutant was injected into New Zealand white rabbits. At a final antiplasma dilution of 1 : 1050 the lowest detection limit of leukotriene C4 was 0.046 pmol. The antiplasma cross‐reacted <1% with leukotrienes D4, E4 and F4, while high relative cross‐reaction (86–100%) was obtained with leukotrienes C3, C5 and 11‐trans leukotriene C4. In experiments where known amounts of leukotriene C4 were added to leukocytes suspensions, 67–100% of the added amount was recovered by the method. The radioimmunoassay was used to study leukotriene C4 formation after stimulation of leukocyte suspensions with the ionophore A23187.

Sulfidopeptide-leukotriene peptidases in pulmonary edema fluid from patients with the adult respiratory distress syndrome

The human pulmonary edema fluid concentrations of LTC4 and of LTD4 and LTE4, derived peptidolytically from LTC4, were assessed by radioimmunoassays of the mediators resolved by reverse-phase high-performance liquid chromatography. The mean pulmonary edema fluid concentration (± SD) of LTD4 of 19.2±25.6 nM for 12 patients with the adult respiratory distress syndrome and of LTE4 of 192±309 nM for 10 of the patients were significantly higher (P<0.005 andP<0.05) than those of 2.2±2.4 and 11.0±18.2 nM, respectively, for 10 patients with cardiogenic pulmonary edema, whereas the lower mean concentrations of LTC4 were not significantly different for the two groups. Pulmonary edema fluid from five patients with adult respiratory distress syndrome, one with cardiogenic pulmonary edema, and one with an indeterminate syndrome contained similar concentrations of peptidoleukotriene peptidases. The LTC4 and LTD4 peptidolytic activities in ARDS fluids were 81 and 142 kD, respectively, by gel filtration. The extents of peptidolysis of [3]LTC4 and [3]LTD4 by 100 µl of pulmonary edema fluid attained respective mean maximum levels of 74.5±2.9% (N=5) and 37.7±10.2% (N=4) after 30 min at 37°C and were inhibited by serine-borate and by cysteine, respectively. The predominance of LTD4 and LTE4 over LTC4 in states of altered pulmonary vascular pressure and permeability thus is attributable to two distinct peptidases.

Selective transduction of human polymorphonuclear leukocyte functions by subsets of receptors for leukotriene B4

Human polymorphonuclear leukocytes express two classes of receptors specific for leukotriene B4 (LTB4). The binding of LTB4 to the high-affinity, low-capacity receptors is critical in eliciting a chemotactic response, as assessed by the stereospecificity of binding and the loss of expression of high-affinity receptors after chemotactic deactivation. The stereospecificity and concentration dependence of LTB4 stimulation of granular enzyme release suggest that the low-affinity, high-capacity receptors mediate this response. Although the LTB4 receptors exhibit properties similar to those of the receptors for peptide chemotactic stimuli, the expression of both classes of receptors on intact polymorphonuclear leukocytes will permit a more complete assessment of the coupling of receptor occupancy to functional activation and the delineation of LTB4 receptor-level defects in human disease states.