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K D Beaman

Publications and source records attributed to K D Beaman.

At least 55 records · Page 3Linked to original sources
PubMed1990

Inhibition of binding of anti-CD3 antibodies to paternal lymphocytes correlates with failure of immunotherapy for treatment of recurrent spontaneous abortions.

A two color flow cytometry crossmatch (FCXM) was used to evaluate the induction of anti-lymphocyte antibodies in 34 women undergoing immunotherapy for recurrent spontaneous abortions. All women had anti-lymphocyte antibodies that reacted with T-cells when analyzed by FCXM. However, inhibition of the binding of anti-CD3 to paternal CD3 lymphocytes in the presence of maternal antipaternal lymphocyte antiserum was found for some couples following lymphocyte immunotherapy for spontaneous recurrent abortions. Ten couples who had another spontaneous abortion following immunotherapy showed inhibition. In contrast, eight couples who did not show inhibition of the binding of anti-CD3 T lymphocytes to paternal lymphocytes by maternal anti-lymphocyte antiserum had live births. Women of the remaining 16 couples were either pregnant and awaiting birth or not pregnant. Thus, by FCXM it may be possible to predict those couples who will have successful pregnancies following this treatment.

Abortion, Habitual↗
PubMed1990

Embryo implantation associated with increase in T-cell suppressor factor in the uterus and spleen of mice.

The concentrations of T-cell suppressor factor (TsF) were examined by competitive binding assays in the uterus, spleen, and regional lymph nodes draining the uterus in Day-5 pregnant mice or in ovariectomized mice given hormone treatments to induce conditions of delayed implantation or implantation. The amounts of immunoreactive TsF on Day 5 of pregnancy were 2.055 +/- 0.302, 0.803 +/- 0.088, 0.426 +/- 0.136 ng TsF/mg extractable protein for the regional lymph nodes, spleen and uterus, respectively, during Day 5 of pregnancy. When implantation was prevented by ovariectomy on Day 4 followed by treatment with only progesterone, amounts of TsF (as a % of Day 5 value) were decreased to 57% in the uterus and increased to 141% in the spleen and 180% in the regional lymph nodes. When implantation was then initiated with the addition of oestradiol-17 beta to the progesterone treatment, amounts of TsF were increased to 206% in the uterus, 318% in the spleen, and remained unchanged at 180% in the regional lymph nodes. These experiments suggest that the amounts of TsF in the uterus and spleen are dependent upon the implantation process, whereas amounts of TsF in the regional lymph nodes are independent of this event.

Animals↗
PubMed1989

An approach to the unification of suppressor T cell circuits: a simplified assay for the induction of suppression by T cell-derived, antigen-binding molecules (T-ABM).

A system is presented in which the in vitro response to sheep red blood cells (SRBC) can be regulated using antigenic determinants coupled to SRBC and T cell-derived antigen-binding molecules (T-ABM) directed against the coupled determinants. T suppressor-inducer factors (TsiF's) are composed of two molecules, one of which is a T-ABM and one which bears I-J determinants (I-J+ molecule). Using two purified T-ABM which have not previously been shown to have in vitro activity, we produced antigen-specific TsiF's which were capable of inducing the suppression of the anti-SRBC response. Suppression was found to require both the T-ABM and the I-J+ molecule, SRBC conjugated with the antigen for which the T-ABM was specific, and a population of Ly-2+ T cells in the culture. Two monoclonal TsiF (or TsF1) were demonstrated to induce suppression of the anti-SRBC response in this system, provided the relevant antigen was coupled to the SRBC in culture. The results are discussed in terms of the general functions of T-ABM in the immune system. This model will be useful in direct, experimental comparisons of the function of T-ABM and suppressor T cell factors under study in different systems and laboratories.

Animals↗
PubMed1989

Analysis of anti-lymphocyte antibodies by flow cytometry or microlymphocytotoxicity in women with recurrent spontaneous abortions immunized with paternal leukocytes.

The identification of anti-lymphocyte antibodies was investigated in women with a history of recurrent spontaneous abortions who received leukocyte immunization treatment. The antibodies were detected by two-color flow cytometric analysis (FCMX) and by microlymphocytotoxicity (MCX). Twice the number of positive patients (women who had been immunized with paternal leukocytes and produced antilymphocyte antibodies) could be identified by flow cytometry versus a standard microcytotoxicity assay (66 versus 33%). In addition, when mixed lymphocyte culture assays were performed to determine if serum blocking factors had been induced, those couples who were positive by FCMX showed inhibition of the mixed lymphocyte culture responses in contrast to most FCMX negative patients who did not. Thus, the sensitivity of the FCMX and its rapidity makes it an alternative to the mixed lymphocyte culture assay for assessing immunotherapy in women with recurrent spontaneous abortions.

Abortion, Habitual↗
PubMed1988

T-cell suppressor factors play an integral role in preventing fetal rejection.

In previous studies we showed that the blocking of T-cell suppressor factors (TsF) with monoclonal antibody could completely ablate pregnancy, and demonstrated the presence of TsF in fetal and maternal tissues. In our current study we used a monoclonal antibody specific for TsF to determine the time during gestation when TsF is most integral in the maintenance of pregnancy. Significant decreases in the number of viable pregnancies when monoclonal antibody was administered on days 3, 4 and 5 were demonstrated. In addition, ELISAs were used to measure the levels of TsF in tissues from pregnant and non-pregnant mice. Increased levels of TsF in the uterus and the lymph nodes draining the uterus were observed when compared to the same tissues of non-pregnant animals. These data strengthen the hypothesis that TsF is in part responsible for the fetal specific immune supression during pregnancy in allogeneic mice and more clearly define the importance of TsF in the implantation of the embryo.

Animals↗
PubMed1988

Induction of abortion in mice with a monoclonal antibody specific for suppressor T-lymphocyte molecules.

A monoclonal antibody, mAb 14-30, which binds T-cell produced suppressor factors (TsF) was used to study the possibility that molecules produced by suppressor T-cells play a role in maintaining pregnancy, presumably by protecting the fetus from the maternal immune system. Female mice were injected with mAb 14-30 at various times after mating. Overall, only 14% of the expected 68% of the mated and treated females were pregnant at term. In addition, Western blots were used to demonstrate the presence of TsF in fetuses, placentae, uteri and spleen of pregnant animals and its presence only in the spleen of non-pregnant animals. These experiments help to confirm results that indicate the importance of immune suppressor factors in maintaining pregnancy and extend these previous observations to include suppressor T-cell molecules.

Abortion, Induced↗
PubMed1987

A helper T cell clone produces an antigen-specific molecule (T-ABM) which functions in the induction of suppression.

Among Ly-1+,2-T cells there appears to be two independent modes of antigen recognition. Helper and cytotoxic Ly-1 T cells recognize antigen only in the context of I region products whereas regulatory T cells, such as T suppressor inducer cells, produce antigen-specific, antigen-binding molecules (T-ABM). These T-ABM often have been found to form a part of biologically active, antigen-specific regulatory factors. A number of environmental conditions effect whether a foreign antigen will produce a positive response leading to immunity or a negative one leading to tolerance. Many of the conditions which favor the induction of suppressor T cells simultaneously preclude the proper interaction of antigen presenting cells with helper T cells. This parallel led us to ask whether helper T cells perform at least two, apparently opposite functions: a) under conditions favoring immunity helper T cells produce lymphokines to activate immune effector cells, and b) under conditions favoring suppression they produce molecules which function in suppressor cell induction. Therefore, this question relates to the mechanisms by which an immune response is switched into either a positive (help) or negative (suppressive) track. In addition, it begins to address the relationship between the different modes of antigen recognition exhibited by helper T cells vs. T suppressor inducer cells (see above). To explore this problem we employed an antigen-specific, I-Ak restricted helper T cell clone as the purest available source of helper T cells. We presented antigen to the cloned T cells under conditions which favor suppression rather than help (for example, by ultraviolet irradiation of the antigen-presenting cells) and collected supernatants 48 hrs later. The supernatants were then examined for activity in a functional assay for antigen-specific suppressor factors. Our results indicate that under conditions favoring suppression, a T-ABM was produced which functioned in the antigen-specific induction of suppression in vitro. The T-ABM had the same antigen specificity as that exhibited by the helper T cell and was therefore probably derived from the clone. This observation introduces the possibility that the interaction between antigen-presenting cells and helper T cells is a crucial decision point in the immune response which can lead to either immunity or suppression. The latter would be achieved through the production, by helper T cells, of an antigen-specific component of T suppressor inducer factor (i.e., the T-ABM). The possible relationship between T-ABMs and the T cell receptor is discussed.

Animals↗
PubMed1986

Isolation of antigen-binding membrane molecules from an antigen-specific T-cell hybrid.

Cell surface-radioiodinated proteins of a murine T-cell hybrid specific for and able to bind azobenzenearsonate were isolated by adsorption to Sepharose beads conjugated with a rabbit antiserum to murine T-cell antigen-binding molecules. These isolated proteins, Mr 72,000, were found to bind specifically azobenzenearsonate while proteins isolated in this manner from the tumor parent BW5147 did not bind azobenzenearsonate. Similar cell surface proteins were isolated by affinity for antigen and immunoprecipitated with an antiserum to T-cell antigen-binding molecules. The results suggest that antigen-binding T cells express T-cell antigen-binding molecules as membrane receptors for antigen.

Animals↗
PubMed1986

Phenotypic similarity between T-cell antigen binding molecules.

T-cell antigen binding molecules (TABM) specific for trinitrophenol (TNP), oxazalone, azobenzenearsonate or sheep erythrocytes were purified by affinity to antigen, adsorption to monoclonal antibodies to antigen binding molecules or were synthesized by translation of immunopurified mRNA for TABM in vitro. These molecules and a T-cell line, BW5147, membrane protein bound by rabbit antibodies to TABM were radiolabeled by 125I, digested with Staphylococcus V8 protease, and peptides of the proteolytic digest were resolved by 2D-gel peptide mapping. Comparison of the peptide maps of these proteins and amino acid analysis of T-cell antigen binding molecules specific for TNP or sheep erythrocytes indicate similarities and distinctions suggesting variable and constant domains in these molecules.

Amino Acids↗
PubMed1985

Antigen-binding molecules of T-cells charge heterogeneity and structural lability.

T-cell products released by immune cells during culture and which bind specifically the nominal antigens, trinitrophenol (TNP) or oxazalone, were isolated from culture media by hapten-affinity chromatography and compared by isoelectric focusing and 2D-gel analysis. These proteins and an azobenzenearsonate-specific T-cell product synthesized in vitro by translation of mRNA from an azobenzenearsonate-specific T-cell hybrid were also compared for structural lability of the polypeptides. Polyclonal T-cell antigen-binding molecules (TABM) specific for TNP or oxazalone showed marked charge heterogeneity and distinctions in isoelectric focusing in an acidic pH gradient, while the azobenzenearsonate-specific, clonal T-cell product displayed restricted focusing. All TABM studied showed dissociation of Mr 70,000 polypeptides to Mr 45,000 and 25,000 polypeptides after treatment with guanidine. The results provide further evidence for distinctions and similarities between TABM.

Animals↗
PubMed1985

Isolation and characterization of a T suppressor factor by using a monoclonal antibody.

We have developed a monoclonal antibody to a T cell-derived suppressor factor (TsF) found in the serum of C57BL/6 mice hyperimmune to sheep red blood cells (SRBC). The antibody binds to the SRBC-specific TsF as well as to a TsF (TNP-TsF) from another system differing in both antigen specificity and MHC. It does not bind to unrelated proteins. The antibody inhibits the activity of the SRBC-specific TsF in vitro. By using the monoclonal anti-TsF, we can isolate sufficient quantities of TsF to demonstrate that it fulfills several properties that have been attributed to TsF, namely, MHC restriction, antigen specificity, and the requirement for a second chain. Also, the purified TsF gives a single 68,000 dalton band upon SDS-PAGE gel analysis under reducing conditions. We conclude, therefore, that we have a method of the isolation of pure TsF, as well as a probe for the genetic, biochemical, and biologic analysis of TsF.

Animals↗
PubMed1984

Production and purification of monoclonal T lymphocyte antigen binding molecules (TABM).

T lymphocyte antigen binding molecules are distinct from B cell immunoglobulins. These proteins were produced by an antigen-specific T cell hybrid as monoclonal products and these cells were successfully grown as an ascites. The T cell antigen binding proteins in ascites were harvested and purified in milligram amounts. The procedure we describe should provide a valuable source of large quantities of pure T lymphocyte antigen binding molecules. This method will allow for studies into their mechanisms of function in regulation of the immune response, biochemistry and molecular biology as B cell myelomas and monoclones provided for the study of immunoglobulins.

Animals↗
PubMed1984

Messenger RNA for an antigen-specific binding molecule from an antigen-specific T-cell hybrid.

The T-cell hybridoma 51H7D specifically binds the hapten azobenzenearsonate (ABA). An antiserum (anti-PCIF) specific for antigenic determinants shared by antigen-binding molecules of T cells (TABM) was used to precipitate polyribosomes containing mRNA for TABM from this T-cell hybridoma. The resultant mRNA was translated in vitro. The translated product (TrP51H7D) bound specifically ABA and was bound by both anti-PCIF and anti-T-cell suppressor factor. The parent lymphoma BW5147 yielded a similar translated product with the same antiserum used to isolate specific mRNA containing polysomes. This product (TrPBW) was bound by the antiserum used but did not bind ABA. The specific translated protein from both cells had a pI of approximately equal to 5.0, and apparent molecular weight of 71,000 (reduced) or 145,000 (nonreduced). Both protein products, when treated with guanidine to break down all noncovalent bonds, revealed an elemental peptide of Mr 23,500. The cDNA made from the isolated mRNA had 600-900 bases. mRNA of this size is expected for a protein of Mr 25,000. Our data indicate that a TABM specific for ABA is composed of peptides of Mr 23,500.

Animals↗
PubMed1983

Synthesis of adenylate nucleotides by Mollicutes (mycoplasmas).

Cultures of the Mollicutes (mycoplasma) Acholeplasma laidlawii B, Acholeplasma morum, Mycoplasma bovis, Mycoplasma arginini, Mycoplasma fermentans and Mycoplasma gallisepticum, representing four metabolic groups, were sampled at intervals over a 40 to 50 h period and assayed for the numbers of c.f.u., changes in pH and glucose concentration, and concentrations of ATP, ADP, AMP, lactate and pyruvate. The adenylate energy charge (ECA), the mean generation time, and the number of nmol of ATP (mg dry weight)-1 were calculated for cultures in the mid-exponential growth phase. The maximum cell concentrations ranged from 0.2 X 10(10) to 5.0 X 10(10) c.f.u. ml-1. Doubling times ranged from 0.34 to 3.29 h. The fermentative, nonarginine-requiring A. laidlawii B, A. morum, and M. gallisepticum, as well as the fermentative, arginine-requiring M. fermentans, utilized glucose and produced lactate and pyruvate. The non-fermentative, non-arginine-requiring M. bovis neither utilized glucose nor produced lactate or pyruvate. The non-fermentative, arginine-requiring M. arginini utilized glucose, but did not produce lactate or pyruvate. At mid-exponential growth phase, the average ECA of A. laidlawii B was 0.90, a value similar to that reported for Spiroplasma citri and other bacteria. In contrast, the average ECA of A. morum and the four Mycoplasma species was 0.70. In A. laidlawii B at mid-exponential growth phase, ATP accounted for 97% of the total adenylate nucleotide pool.(ABSTRACT TRUNCATED AT 250 WORDS)

Acholeplasma↗
PubMed1981

Adenylate energy charge in Acholeplasma laidlawii.

Adenosine 5'-triphosphate, adenosine 5'-diphosphate, and adenosine 5'-monophosphate were produced by Acholeplasma laidlawii B-PG9 growing in modified Edward medium. The adenylate energy charge was calculated to be 0.84 +/- 0.07 and ranged from 0.91 to 0.78 during exponential growth (12 to 24 h). During exponential growth, A. laidlawii contained, at 17.5 h, 2.3 X 10(-17) mol of adenosine 5'-triphosphate per colony-forming unit and, at 16 h, 27.3 nmol of adenosine 5'-triphosphate per mg (dry weight). The medium supported a doubling time of 0.95 h. The molar growth yields (Yglucose = grams [dry weight] per mole of glucose used) were 40.2 +/- 3.4 (16 h) and 57.1 +/- 9.7 (20 h) during midexponential growth. A maximum yield of 8.3 X 10(9) colony-forming units was reached at 24 h, when 56% of the initial concentration of glucose had been used. At 40 h, during the stationary phase, 14.95 +/- 3.75 mumol of glucose per ml of medium had been used. At this time, the culture fluids contained 21.86 +/0 mumol of lactate per ml and 3.14 +/- 0.13 mumol of pyruvate per ml.

Acholeplasma laidlawii↗
PubMed1979

Antioxidants reduce the mutagenic effect of malonaldehyde and beta-propiolactone. Part IX. Antioxidants and cancer.

Increasing concentrations of malonaldehyde and beta-propiolactone were increasingly mutagenic with 7 mutants of Salmonella typhimurium, 5 of which mutated bya frameshift mechanism and 2 of which mutated through base-pair substitution. The antioxidants vitamin C, vitamin E, selenium and butylated hydroxytoluene (BHT) at 3 logarithmic concentrations markedly reduced mutagenesis in those strains which mutated by frameshift mechanism.

Ascorbic Acid↗
PubMed1979

Effects of blood on blood culture medium.

The morphological and biochemical changes that occur after inoculation of sterile blood into a blood culture medium (tryptic soy broth) with sodium polyanetholesulfonate and CO(2) were investigated. Cellular changes, pH, PCO(2), and PO(2) were monitored and evaluated. Erythrocytes became crenated and developed precipitated hemoglobin inclusions within 4 h. The lymphocytes appeared morphologically intact at 24 h, and by 48 h a few cells had undergone transformation. Many neutrophils were vacuolated at 24 h. Neutrophils capable of phagocytizing Staphylococcus aureus were observed after 18 h of incubation. Identifiable eosinophiles were present on day 6 of the study. A decrease in PO(2) in the unvented bottles from 44.4 to 8 mm of Hg occurred by 24 h. PO(2) remained low for 6 days, after which a slight increase occurred. An increase in PO(2) in the vented bottle from 51 to 58 mm of Hg occurred by 24 h of incubation. In both the vented and unvented bottles the PCO(2) increased. This increase was markedly more rapid in the unvented bottle. From a pH of 7.06 a decrease occurred for the first 24 h after inoculation, with the pH stabilizing at 6.8 in the vented bottles and at 6.6 in the unvented bottles. The biochemical changes that occurred in the vented culture bottles stabilized more rapidly than those of the unvented bottles. Changes caused by the addition of sterile blood to a blood culture medium resulted in conditions which departed considerably from accepted optima for the isolation of clinically important microorganisms. The phagocytosis of organisms that occurred may also have reduced the yield.

Bacteria↗