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L B Lachman

Publications and source records attributed to L B Lachman.

72 records · Page 4Linked to original sources
PubMed1982

Prevention of the in vitro myelosuppressive effects of glucocorticosteroids by interleukin 1 (IL 1).

We investigated the effects of dexamethasone on the formation of granulocyte/macrophage colonies by murine bone marrow cells cultured with colony-stimulatory factors (CSF) in semisolid agar. Dexamethasone (10(-7) M) completely inhibited the formation of colonies in response to L929 CSF but had no effect on the response to CSF in the culture supernatants of the murine macrophage cell line, PU5-1.8. We postulated that a cofactor, interleukin 1, present in the PU5-1.8 supernatants was responsible for protecting colony formation against steroid suppression. Interleukin 1, isolated from culture supernatants of PU5-1.8 and from culture supernatants of human acute monocytic leukemia cells, blocked the inhabitory effects of dexamethasone on colony formation in response to L929 CSF. Moreover, dexamethasone inhibited colony formation in response to PU5-1.8 culture supernatants when interleukin 1 was absent. We also examined interleukin 2 for possible protective effects. Although crude interleukin 2 preparations (supernatants of spleen cells cultured with concanavalin A) blocked dexamethasone inhibition, purified interleukin 2 had no protective effects. These data indicate that interleukin 1 protects colony formation by a pathway that is independent of interleukin 2 and that supernatants of spleen cells activated with concanavalin A probably contain significant amount of interleukin 1.

Animals↗
PubMed1982

Heterogeneity of human monocyte subsets in the promotion of B cell colonies and the role of interleukin 1.

The abilities of human peripheral blood mononuclear-phagocyte (M phi) subpopulations and of interleukin 1 (IL 1) to support human B cell colony formation in semisolid cultures stimulated by staph protein A were analyzed. Human M phi subsets enriched for complement receptors (CR) effectively functioned as accessory cells supporting colony growth, whereas the responses obtained with CR-depleted M phi were 4.6-fold less. In experiments analyzing IL 1 production, CR-enriched M phi secreted four to 12 fold greater amounts of basal and stimulated IL 1 than CR-depleted M phi. Also, the addition of IL 1 to CR-depleted M phi resulted in a fourfold increase of colony numbers. The responses of cultures containing CR-depleted M phi plus IL 1, however, remained 30% less than those observed for cultures supplemented with CR-enriched M phi. Other studies showed that IL 1 was unable to substitute for M phi; the responses of cultures containing IL 1 and B cells were reduced 10-fold compared to cultures supplemented with autologous M phi. These findings indicate that human M phi subsets exist that differ in their ability to function as accessory cells. Although IL 1 can collaborate with certain M phi subsets to restore their accessory cell function, it cannot replace intact M phi. Thus, it is possible that other monokines or lymphokines play a role in M phi accessory cell function.

B-Lymphocytes↗
PubMed1981

Effect of interleukin 1 on human thymocytes and purified human T cells.

Human Interleukin 1 (IL-1) purified by molecular weight fractionation, isoelectric focusing, and gel electrophoresis has been tested on human thymocytes and highly purified human T cells. IL-1 prepared in this manner could not support the long-term growth of T cells yet would augment lectin-stimulated mitogenesis. The IL-1 preparations were shown to possess the lectin-augmenting activity at dilutions containing less than 1 ng of the measurable protein. These data are in agreement with the model that IL-1 stimulates production of IL-2 from lectin-stimulated lymphocytes.

Cell Separation↗
PubMed1981

Effects of levamisole on the proliferation of thymic lymphocyte subpopulations.

The ability of levamisole to enhance proliferation of murine lymphocyte preparations stimulated by concanavalin A was examined. Levamisole substantially augmented the proliferation of C57Bl/6 thymic lymphocytes, but had only marginal effects on the proliferation of splenic lymphocytes. The possibility that this difference was related to the degree of cell maturation was examined by peanut agglutinin fractionation of the thymic lymphocytes. Levamisole was found to stimulate proliferation most effectively in the mature fraction. However, since the focus of levamisole activity might be on macrophages, also shown to be present in preparations of splenic and thymic lymphocytes and in both PNA separated fractions, the drug's activity was compared to several macrophage replacements: LAF-IL 1, 2-mercaptoethanol, and added splenic adherent cells. Added plastic adherent cells and 2-mercaptoethanol were effective in augmentation of proliferation of both mature and immature populations whereas LAF-IL 1 like levamisole was most effective on the mature population.

Animals↗
PubMed1981

Human T lymphocyte/monocyte interaction in response to lectin: kinetics of entry into the S-phase.

PHA-mediated mitogenesis of human peripheral blood T lymphocytes was studied by using highly purified cell populations. The kinetics of human, mature T cell [3H]-Tdr incorporation were examined with respect to those elements necessary and sufficient for the progression of the activated T cell into the S-phase of the cell cycle. These experiments indicated that although a lectin may independently initiate morphologic T cell blastogenesis, this event is not associated with significant progression through the G1 phase of the cell cycle. This blastogenic response is associated with the subsequent T cell receptivity to monocyte-initiated cell cycle progression, and the effect of monocytes can be substituted by partially purified Interleukin 1 (IL-1). Progression of a lectin exposed T cell into the S-phase of the cell cycle could also be achieved by exposing the activated T cell to partially purified Interleukin 2 (IL-2). Given the prior demonstrations that IL-1 functions to induce the T cell-dependent production of the IL-2, it appears that IL-2 is the requisite signal necessary for the activated human lymphocyte to actually progress through the prereplicative phase of the cycle into the S-phase.

Cell Communication↗
PubMed1981

Classification of human leukemia by membrane antigen analysis with xenoantisera.

Rabbit and monkey antisera after appropriate absorption were rendered specific for normal or leukemic lymphoid- and myeloid-associated antigens. Antisera defining a common peripheral blood T-cell antigen, a thymus leukemia antigen, HLA-DR or Ia-like antigen, common acute lymphoblastic leukemia antigen (CALLA), and a myeloid-monocyte (M) antigen were used in a microcytotoxicity assay to classify leukemic cells from 30 patients in a double blind study. The antisera to the M antigen reacted with adherent peripheral blood cells and polymorphonuclear leukocytes and failed to react with nonadherent mononuclear cells and enriched T-cells and chronic lymphocytic leukemia cells. The M antisera also reacted with U937, a monocytic-type cell line, and with HL60, a promyelocytic-type cell line, but failed to react with T and B lymphoblastoid cell lines. The specificities of the other antisera have been described in previous reports. Cells from three of the patients could not be phenotyped by microcytotoxicity testing. Cells from 25 patients had a consensus morphological or histochemical diagnosis of either acute lymphoblastic leukemia or acute nonlymphocytic leukemia. The serological classification of these patients using the five types of antisera listed above were consistent with the consensus diagnosis. In addition, the lymphoid cancers were further subclassified as to T-, B-, or thymus antigen types. There was no consensus lymphoid versus myeloid diagnosis on cells from two patient. The serological classification in both cases favored a diagnosis of myeloid rather than lymphoid leukemia.

Acute Disease↗
PubMed1980

The functional relationship of the interleukins.

The mechanism of the lymphoproliferative effect of the macrophage product lymphocyte-activating factor [LAF(IL1] appears to be mediated by the stimulation of the release of T cell growth factor [TCGF(IL2)] by T cells. The magnitude of the resultant T cell proliferative clonal expansion is thus dependent upon the quantity of both LAF(IL1) and TCGF(IL2) induced by antigen or lectin stimulation. These observations, coupled with the ability to measure the production and actions of these hormone-like lymphokines, should allow for increased insight into the mode of action of immunoenhancing and immunosuppressive agents, as well as for new therapeutic approaches to disease states involving T lymphocytes.

Animals↗
PubMed1980

Purification of human interleukin 1.

Interleukin I (IL-1) is a lymphocyte stimulant released by human monocytes cultured for 18-24 hours in tissue culture medium containing 5% serum and the non-specific immunostimulant lipopolysaccharide (LPS). Human IL-1 is found in the conditioned medium in a low molecular weight (approximately 13,000) and a high molecular weight (approximately 85,000) form. The high MW activity may result from the formation of a complex between IL-1 and serum constituents. During the course of purification, the low MW IL-1 activity is often recovered in a high MW form. Hollow fiber diafiltration and membrane ultrafiltration has been found to rapidly separate low MW IL-1 from all measurable protein with a yield of 4% of the original activity. The IL-1 which converts to the high MW form during the purification is recoverable, 21% of the original activity, but contains small amounts of serum proteins. Isoelectric focusing (IEF) of the low MW IL-1 resulted in a very highly purified sample which was analyzed by polyacrylamide gel electrophoresis (PAGE). Utilizing a new staining procedure which detects less than 1 ng of protein per band, the IEF-purified IL-1 revealed trace quantities (less than 1 ng) of a slowly migrating protein similar to immunoglobulin and no other bands. There were no bands which corresponded with the known electrophoretic mobility of IL-1. Since the samples applied to the gel contained significant biological activity, this result implies that human IL-1 is biologically active in picogram quantities.

Animals↗
PubMed1980

Partial purification of human lymphocyte activating factor.

Lymphocyte Activating Factor (LAF) is a T lymphocyte stimulant released by human monocytes cultured for 18-24 hours in tissue culture medium containing 5% human serum and the non-specific immunostimulant lipopolysaccharide. The purification of LAF is essentially the separation of low MW LAF (approximately 13,000) from the human serum proteins required for production of the activity. Hollow fiber ultrafiltration has been found to effect a rapid separation of low MW LAF from serum proteins, but with a yield of only 20% of the original activity. Isoelectric focusing (IEF) efficiently separates LAF from all traces of human serum, resulting in a purified sample containing no measurable protein and revealing no bands on polyacrylamide gels. The IEF purified material is about 2% of the low MW activity present in the unfractionated culture medium and is highly active in the biological assay system.

Animals↗
PubMed1979

Synthesis of model compounds relevant to the active-site-directed inactivation of L-asparaginase by 5-diazo-4-oxo-L-norvaline.

Earlier work has shown that 5-diazo-4-oxo-L-norvaline (DONV) irreversibly inactivates the L-asparaginase from E. coli by formation of a covalent bond in the region of the active site. Model compounds have been prepared to study this acid-labile covalent bond tentatively assigned to a serine or possibly a threonine residue in a decapeptide isolated from 14C-DONV-inactivated enzyme. Appropriately blocked DONV was found to alkylate methanol, and the hydroxyl function of blocked serine or threonine in the presence of boron trifluoride. The labile beta-ketoethers thus formed were reduced to the more stable beta-hydroxyethers. Facile lactonization of these 5-substituted-4-hydroxy-L-norvalines was observed. The diastereoisomers of both the lactonized and open forms of 5-methoxy-4-hydroxy-L-norvaline and related 4-hydroxy-L-2-amino acids of similar length were distinguishable on the amino acid analyzer. The beta-hydroxyethers derived from serine and threonine were hydrolyzed with acid and yielded the expected cleavage products. When the beta-ketoether was reduced by sodium borohydride prior to deblocking, in addition to the beta-hydroxyether, N-blocked amino alcohols were also formed, yielding a complex mixture of products.

Alkylation↗
PubMed1977

Partial purification of human lymphocyte-activating factor (LAF) by ultrafiltration and electrophoretic techniques.

Lymphocyte-activating factor (LAF) has been produced by culturing human peripheral blood leukocytes in the presence of lipopolysaccharide and autologous human serum. The major LAF activity, identifiable by Sephadex chromatography (m.w. 13,000) was separated from most serum proteins in the culture medium by ultrafiltration with a hollow fiber device. Sucrose gradient isoelectric focusing of the concentrated ultrafiltrate yielded a single peak of LAF activity with an average isoelectric point of pH 6.8. Semi-preparative polyacrylamide gel electrophoresis of the isoelectric focusing sample resulted in separation of the LAF activity from detectable amounts of serum proteins. The recovered LAF activity was estimated to be purified more than 16,000-fold and is judged to be active in submicrogram amounts.

Animals↗
PubMed1976

The active site of L-asparaginase: dimethylsulfoxide effect of 5-diazo-4-oxo-L-norvaline interactions.

The asparagine analog, 5-diazo-4-oxo-L-norvaline is a substrate and an irreversible inhibitor of L-asparaginase. Covalent attachment occurs at an increased rate at concentrations of dimethylsulfoxide which reduce the catalytic decomposition of diazo-oxo-norvaline. In 55% dimethylsulfoxide asparaginase is inactivated by diazo-oxo-norvaline (0.05 M) with a t 1/2 of twelve seconds. In aqueous buffer the rate of diazo-oxo-norvaline decomposition is increased three-fold in the presence of the nucleophile hydroxylamine; this nucleophile also protects the enzyme against inactivation by diazo-oxo-norvaline in the presence of dimethylsulfoxide.

Aminolevulinic Acid↗
PubMedDate not supplied

Antigen presentation by liposomes bearing class II MHC and membrane IL-1.

Liposomes containing membrane IL-1, Iak, and the antigen conalbumin were evaluated as "synthetic antigen presenting cells." The role of these three molecules in macrophage-T cell interaction was studied by testing their ability to induce the proliferation of a T-cell clone specific to conalbumin (the D10 cell line) or immune spleen cells sensitized three times in vivo with conalbumin. In the latter case, splenic macrophages were eliminated by adherence and a lysomotropic agent. The antigen conalbumin was presented on the surface of the liposomes as native undigested protein. When the liposomes presented native conalbumin, Iak, and membrane IL-1, significant proliferation occurred, but if the liposomes lacked membrane IL-1, the proliferation of the T-cell clone and the spleen cells reached only about 60 percent of the previous signal. Native conalbumin and class II antigen alone were required for T-cell activation, while membrane IL-1 only amplified the response. When the liposomes were made with only Iak and membrane IL-1, lacking conalbumin, there was no proliferation of antigen-specific target cells. These results indicated that in this synthetic system, membrane IL-1 increases the magnitude of the response but is not essential for the proliferative response of antigen-specific T cells.

Animals↗