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H S Warren

Publications and source records attributed to H S Warren.

At least 73 records · Page 4Linked to original sources
PubMed1988

Control of endotoxin activity and interleukin-1 production through regulation of lipopolysaccharide-lipoprotein binding by a macrophage factor.

Lipopolysaccharides (LPSs) extracted from gram-negative bacteria are much less active when bound to serum lipoproteins. We present evidence here that the binding of radiolabeled LPS extracted from Escherichia coli O113 and Salmonella typhimurium to lipoproteins in rabbit serum is increased 8 to 24 h after a single intravenous injection of homologous or heterologous LPS. Supernatants of activated macrophages containing interleukin-1 also stimulate increased binding. The isolated product of this binding does not induce the production of interleukin-1 by macrophages in vivo or in vitro and is unable itself to stimulate increased binding of LPS to lipoprotein. Normal rabbit sera spiked with lipoprotein fractions prepared from tolerant but not normal rabbit sera bind increased amounts of LPS. These data suggest that there may exist a self-regulated mechanism for decreasing the toxicity of LPS and the production of LPS-induced interleukin-1; this mechanism is controlled by a macrophage factor and functions through altering the binding of LPS to certain serum lipoproteins.

Animals↗
PubMed1988

The T11(3) epitope of the CD2 molecule, sheep erythrocytes, and the alternative T-cell activation pathway.

In this study, results are presented showing that the T11(3) epitope of the CD2 molecule is expressed on unfractionated peripheral blood mononuclear cells, resting T cells and activated T cells. T11(3) is not therefore, an activation-specific CD2 epitope. Sheep erythrocytes (SRC) which present a cell-surface ligand for CD2 could not effectively replace anti-T11(2) in initiating proliferation of resting T cells, stimulated by anti-T11(3). SRC with either of these anti-CD2 monoclonal antibodies did activate resting T cells, but proliferation required the presence of added IL-2.

Animals↗
PubMed1988

Future prospects for vaccine adjuvants.

Since the landmark experiments of Ramon 60 years ago, attempts have been made to augment the humoral and cellular responses to administered antigens in order to develop more potent and less toxic vaccines. The need for an acceptable adjuvant suitable for clinical use has been underscored by recent advances in recombinant biotechnology and synthetic chemistry which have made it possible to create antigens that are smaller and better characterized, yet less immunogenic, than before. It is likely that these antigens will require an adjuvant to achieve protective immunity. Some of these same technological advances, together with a better understanding of the immune system in general, have permitted the study of adjuvants to evolve from an empirical field to a developmental one. This article discusses the currently known agents capable of immunopotentiation and possible strategies for their use in future vaccines.

Adjuvants, Immunologic↗
PubMed1987

Endotoxin neutralization with rabbit antisera to Escherichia coli J5 and other gram-negative bacteria.

To study the mechanisms of protection against endotoxin challenge offered by antisera to smooth and rough gram-negative organisms, we have developed an assay to quantitate endotoxin neutralization based on inhibition of the Limulus amoebocyte lysate test. Dilutions of different bacterial lipopolysaccharides (LPSs) were incubated with hyperimmune rabbit sera against Escherichia coli O113, E. coli O18, and rough mutants E. coli J5 and Salmonella minnesota Re595 and were then combined with limulus lysate. The gelation reaction induced by LPS in the lysate was monitored spectrophotometrically, and the concentration of LPS resulting in a 50% lysate response was determined and correlated with antibody titers measured by enzyme-linked immunosorbent assay. Antisera to smooth organisms neutralized homologous LPS markedly and heterologous LPSs only minimally relative to neutralization by preimmune serum. Neutralization of homologous LPS occurred immediately without preincubation of serum and LPS. Antisera to rough mutants neutralized more heterologous LPS than did antisera to smooth organisms. However, this heterologous neutralization required preincubation of serum and LPS and did not appear to be correlated with antibody concentrations. We conclude that antisera to LPS rapidly neutralize the biological activity of the homologous LPS, as detected by limulus lysate, and that neutralization is at least in part antibody mediated. Antisera to rough-mutant organisms slowly neutralized the activity of heterologous LPSs, but this effect appeared not to be correlated with concentrations of antibody to the LPS of the rough mutant, as measured by enzyme-linked immunosorbent assay.

Animals↗
PubMed1987

Role of interleukin-1 in augmenting serum neutralization of bacterial lipopolysaccharide.

We have previously described an assay to quantify the serum neutralization of bacterial lipopolysaccharide which is based on a spectrophotometric Limulus amoebocyte lysate test (T.J. Novitsky, P.F. Roslansky, G.R. Siber, and H.S. Warren, J. Clin. Microbiol. 21:211-216, 1985). Studies since have shown that serum samples drawn from patients with leukemia and fever, gram-negative or gram-positive bacterial infections, or shock caused by gram-negative bacteria neutralize approximately 10-fold more lipopolysaccharide than do samples from normal controls. These findings suggested that the increased neutralization might reflect an acute-phase response and raised the question of whether it might be under the control of interleukin-1. To answer this question, we studied the neutralization of lipopolysaccharide in serum samples drawn from rabbits before and after the administration of crude interleukin-1, prepared from activated macrophage supernatants, and recombinant human interleukin-1. Crude interleukin-1 induced a 5.7-fold increase in serum neutralization 24 h after intravenous injection, and cloned interleukin-1 induced a 3.0-fold increase (P less than or equal to 0.01 and 0.05, respectively). In individual rabbits given identical doses of crude interleukin-1 on a weight basis, the serum-neutralizing ability correlated significantly with three activities of interleukin-1: rise in temperature (r2 = 0.558; P less than or equal to 0.01), decrease in serum iron (r2 = 0.534; P less than or equal to 0.01), and increase in serum copper (r2 = 0.323; P less than or equal to 0.05). We conclude that the increase in neutralization of bacterial lipopolysaccharide by serum samples drawn from patients with inflammatory states is mediated, at least in part, by interleukin-1, presumably through the induction of acute-phase serum proteins.

Animals↗
PubMed1987

Heterogeneity in the activation requirements of T cells stimulated by phytohaemagglutinin.

Data are presented showing that resting T cells proliferated in response to phytohaemagglutinin (PHA) provided that either sheep erythrocytes (SRC) or interleukin-2(IL-2) was added. Proliferation requiring PHA and SRC was inhibited by anti-CD2 monoclonal antibody (OKT11) and anti-CD3 monoclonal antibody (OKT3). These monoclonal antibodies only partially inhibited IL-2 production stimulated by PHA and SRC, and added IL-2 did not restore proliferation in these cultures. Low concentrations of cyclosporine inhibited both proliferation and IL-2 production (ED50 = 12 and 9 ng/ml, respectively) and this inhibition was partially relieved in the presence of added IL-2 (ED50 = 110 ng/ml). In contrast, proliferation stimulated by PHA with exogenous IL-2 was not inhibited in the presence of OKT11, and moderate concentrations of cyclosporine were required to inhibit proliferation (ED50 = 49 ng/ml). Evidence was obtained, from analysis of cultures at limiting dilution, to suggest that the different requirements for stimulation of PHA-responsive T cells reflected different T-cell subpopulations. The majority of PHA-responsive cells proliferated in the presence of PHA and SRC, whereas only a minority proliferated in the presence of PHA and exogenous IL-2.

Antibodies, Monoclonal↗
PubMed1986

Cyclosporin inhibits a two-signal mechanism for the generation of cytotoxic NK-like cells, from small lymphocyte precursors.

Cytotoxic cells resembling NK cells are generated from CD 3- small, lymphokine (LK) nonresponsive precursor cells during an 8 day culture period with mitomycin C-treated autologous T cell blasts and LK. Recombinant interleukin 2 (rIL2) can replace LK in this coculture system. Both stimuli are required for the generation of the cytotoxic cells, which can then be maintained in short term cultures by LK alone. The generation of the cytotoxic cells was inhibited in cultures containing 0.1 micrograms/ml cyclosporin (Cys). Cys did not inhibit the LK dependent growth of the cytotoxic cells. Cys also inhibited the mitogen and LK dependent stimulation of purified T cells, but did not inhibit the LK dependent proliferation of T cell blasts. In contrast to the results for the generation of the cytotoxic cells, Cys did not inhibit the activation/growth of peripheral blood NK cells by LK or rIL2. These studies support the notion that the precursors of the NK-like cytotoxic cells are at an earlier stage of differentiation than peripheral blood NK cells responsive to LK alone, and that the precursor cells are triggered into a differentiation pathway leading to the NK-like cytotoxic cells by a two-signal mechanism.

Cell Differentiation↗
PubMed1986

Neutralization and lipoprotein binding of lipopolysaccharides in tolerant rabbit serum.

We examined the ability of sera drawn from rabbits made tolerant to lipopolysaccharide (LPS) from Escherichia coli O18 to inhibit heterologous LPS-induced gelation of Limulus lysate. Compared with a pool of pretolerant sera, a pool of tolerant sera from these rabbits neutralized 5.5-fold more LPS from Salmonella typhimurium, 4.9-fold more LPS from Pseudomonas aeruginosa, and 10.0-fold more LPS from Klebsiella pneumoniae. Because previous studies have found that LPS bound to lipoprotein is less toxic than unbound LPS, we also studied the binding of LPS lipoprotein fractions in the serum pools by using fractionation with a cesium chloride-equilibrium density gradient. Radiolabeled LPS from E. coli O113 bound much more rapidly to lipoprotein fractions in tolerant serum than in pretolerant serum (after 11 min of incubation, 66.1% vs. 16.5% binding, respectively).

Animals↗
PubMed1986

Rejection of cultured thyroid allografts by the transfer of sensitized LYT 2+ T cells.

Cultured BALB/c (H-2d) thyroid allografts, which are accepted permanently in fully immunocompetent allogeneic CBA/H (H-2k) recipients, are rejected following the transfer of immune spleen cells generated by immunization of recipient-strain mice with P815 (H-2d) which, like the cultured thyroid, expresses only class I major histocompatibility (MHC) antigens. Depletion of Lyt 2+ T cells from the transferred population abolished the capacity of immune spleen cells to trigger rejection, whereas depletion of L3T4+ T cells was without effect. Transfer of in-vitro-activated H-2d specific Lyt 2+ T cells also triggered rejection of cultured thyroid allografts. The results are consistent with previous studies showing that sensitized Lyt 2+ T cells are required for rejection of cultured pancreatic islet allografts, which also express only class I MHC antigens. These results are in accord with the notion that Lyt 2+ T cells are activated by and are active against class I MHC antigens.

Animals↗
PubMed1985

Preparation and characterization of human bone marrow-derived macrophages.

Bone marrow-derived macrophages were prepared from human bone marrow mononuclear cells following cultivation in GCT-conditioned medium (GCT-CM) and purification by adherence to fibronectin-coated flasks. The growth of bone marrow mononuclear cells in GCT-CM was dependent on the shape of the culture vessels, being increased in round-bottomed versus flat-bottomed wells. Proliferation was confined to nonadherent cells; like blood monocytes, bone marrow-derived macrophages did not incorporate [3H]thymidine in response to GCT-CM or human serum. Purified macrophages from this source expressed nonspecific esterase and OKM1, OKla, FMC 17, 32, and 34 and 25F9 antigens but lacked Mo2. They expressed high levels of an inactivator of plasminogen activator, minactivin, and gave a substantial metabolic burst in response to phorbol myristate acetate or opsonized (but not unopsonized) zymosan. Bone marrow-derived macrophages acted as accessory cells in the response of T lymphocytes to phytohemagglutinin. The results suggest that liquid bone marrow cultures are useful in the study of the differentiation of human mononuclear phagocytes.

Antibodies, Monoclonal↗
PubMed1985

Cross-reactivity of rabbit antibodies to lipopolysaccharides of Escherichia coli J5 and other gram-negative bacteria.

Antiserum to rough gram-negative mutants such as Escherichia coli J5 and Salmonella minnesota Re595 is thought to neutralize the toxic effects of lipopolysaccharides (LPSs). To verify that such antisera are capable of binding heterologous endotoxins, we examined IgG and IgM class antibodies induced in rabbits to a variety of LPSs. Immunization with rough mutants or lipid A induced high IgG antibody responses to the homologous purified LPS and relatively low but significant responses to heterologous LPSs. Increases in IgM antibodies were also primarily to homologous LPS. Immunization with smooth organisms induced little or no antibody to heterologous LPSs. Soluble LPS, outer membrane vesicles, and whole bacteria produced strong homologous inhibition but little or no heterologous inhibition in enzyme-linked immunosorbent assays. Cross-adsorption of antisera to rough mutants suggested that the IgG and IgM antibodies induced to heterologous LPS were adsorbed by the heterologous LPS and not by the core LPS used to immunize the animals. Rabbit antibody directed to J5 or Re595 LPS fails to bind to any substantial degree to heterologous LPS. Immunization with whole bacterial vaccines, particularly the rough mutants and lipid A, does increase antibody to a wide variety of antigens. The possibilities that the protective effects of antisera to rough mutants are due to a polyclonal antibody response or to the induction of as yet unidentified factor(s) deserve further investigation.

Animals↗
PubMed1985

Binding and neutralization of bacterial lipopolysaccharide by colistin nonapeptide.

Polymyxin nonapeptides, proteolytic derivatives of polymyxin antibiotics, are less toxic than their parent compounds but retain some of their antibacterial activities. To confirm and expand observations that polymyxin nonapeptides have anti-endotoxin activity, we studied the ability of colistin nonapeptide to bind to bacterial lipopolysaccharide (LPS) and to inhibit the effects of LPS on Limulus amoebocyte lysate and lymphocyte mitogenicity. Colistin nonapeptide was purified by high-pressure liquid chromatography and was demonstrated to bind to LPS by equilibrium dialysis. The ability of colistin nonapeptide to render E. coli ATCC 25922 cells sensitive to erythromycin was abrogated by 50% after incubation with E. coli O18 LPS in a ratio by weight of LPS to colistin nonapeptide of 3.9:1. The presence of 4 micrograms of colistin nonapeptide or colistin per ml increased by 130- and 800-fold, respectively, the concentration of E. coli O113 LPS required to produce 50% gelation of Limulus amoebocyte lysate as measured by a spectrophotometric assay. Neutralization of LPS by colistin nonapeptide was time and concentration dependent. In contrast to the neutralization seen with LPS derived from a colistin-sensitive organism, colistin nonapeptide neutralized very little LPS extracted from a strain of Serratia marcescens that was resistant to colistin. Colistin nonapeptide also inhibited LPS-induced [3H]thymidine uptake by splenic lymphocytes, but its activity was less than 1/10 that of colistin. We conclude that colistin nonapeptide binds to LPS and possesses antiendotoxin activity. However, the anti-endotoxin activity of the nonapeptide is considerably less than that of its parent compound, colistin.

Chromatography, High Pressure Liquid↗
PubMed1985

Turbidimetric method for quantifying serum inhibition of Limulus amoebocyte lysate.

This study describes a method to quantify the inhibition of lipopolysaccharide (LPS) activity by serum with a turbidimetric Limulus amoebocyte lysate assay. Assays were performed in multiwell microplates, and turbidity was measured as the optical density at 380 nm with a microplate spectrophotometer. LPS potency was measured as the 50% maximal Limulus amoebocyte response (LR50) of LPS diluted with saline. By comparing LR50s in saline, LPSs from various species of bacteria were standardized against the U.S. Reference Standard Endotoxin, lot EC-5. The potency of Escherichia coli O113 and O18 and Serratia marcescens LPSs was found to be equal to that of the reference standard EC-5, whereas LPSs from two salmonella species were half as potent. The least potent LPSs tested, obtained from Klebsiella pneumoniae and E. coli rough mutant J5, were 5- and 10-fold less potent, respectively, than EC-5. As a measure of inhibition, the LR50 of LPS in serum was compared to the LR50 of LPS in saline. Serum inhibited the potency of LPS 103- to 6,400-fold compared with saline. A positive correlation was found between standardized potency in saline and serum inhibition of the various LPSs tested. Thus, LPSs from E. coli O113, O18, and EC-5 and S. marcescens, which exhibited the highest potency in saline, were inhibited the most by serum. Likewise, E. coli J5 and K. pneumoniae LPSs, which were the least potent tested, were the least inhibited. The degree of inhibition of all types of LPS tested increased with increasing serum concentration.

Blood↗
PubMed1985

Neutralization of bacterial lipopolysaccharides by human plasma.

To quantify the neutralization of bacterial lipopolysaccharide (LPS) by human plasma, dilutions of Escherichia coli O113 LPS were incubated with plasma, followed by the addition of Limulus amebocyte lysate (LAL). The reaction between the LPS and LAL was monitored spectrophotometrically, and the concentration of LPS resulting in 50% lysate response (LR50) was determined. Analysis of 145 outdated plasma samples yielded a range of LR50 between 6 and 1,500 ng/ml. Pools of plasma with high and low LR50 were prepared. The pool with high LR50 neutralized 166-fold more E. coli 0113 LPS, 190-fold more E. coli 0111B4 LPS, 42-fold more Klebsiella pneumoniae LPS, and 29-fold more Salmonella typhimurium LPS than did the pool with low LR50. Each pool had similar immunoglobulin G (IgG) and IgM antibody levels to homologous LPS, measured by an enzyme-linked immunosorbent assay. Analysis of 212 fresh-frozen plasma units revealed a range of LR50 between 48 and 6,000 ng/ml. Incubation of LPS in a pool of fresh-frozen plasma with high LR50 elicited significantly less fever in the rabbit pyrogen test than did LPS incubated in plasma with low LR50 (fever index, 2.68 +/- 0.61 degrees C X h and 3.52 +/- 0.66 degrees C X h, respectively; P = 0.003). We conclude that there is a 100-fold range in the endotoxin-neutralizing capacity of human plasma and that this variation is not due to LPS-specific IgG or IgM antibodies. Further investigations are needed to determine whether differing susceptibility of patients to the effects of LPS is due to differences in the endotoxin-neutralizing capacity of their plasma and whether plasma screened for high endotoxin-neutralizing capacity may be therapeutically useful in endotoxemia.

Animals↗