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J L Butler

Publications and source records attributed to J L Butler.

At least 37 records · Page 2Linked to original sources
PubMed1985

Synergy of helper factors in the differentiation of in vivo-preactivated antigen-specific human B cells.

After in vivo immunization with antigen, B cells appear in the peripheral blood which can be induced in vitro by nonspecific factors found in mixed lymphocyte culture supernatants (MLC-SN) to differentiate and secrete antibody specific for the immunizing antigen. In order to further delineate the nature of the factors involved in the differentiation of these in vivo-activated B cells, various helper factors, including interleukin 1 and interleukin 2 (IL-1 and IL-2), B-cell growth factor (BCGF), and B-cell differentiation factor (BCDF) were added separately and in combination to cultures of these preactivated B cells. T-cell-depleted fractions of peripheral blood mononuclear cells were obtained from normal individuals immunized in vivo with keyhole limpet hemocyanin. MLC-SN alone, without the addition of antigen, selectively triggered an antibody response specific for the antigen used to immunize in vivo in the absence of a polyclonal B-cell response. In order to obtain responses equal to those seen with MLC-SN, a combination of BCGF, IL-2, and BCDF was required, although any two factors partially reconstituted the response. Exogenous IL-1 had the least effect but was suppressive in the presence of optimal concentrations of monocytes. Thus, for maximal in vitro differentiation of in vivo-preactivated B cells, a combination of at least three helper factors is required and acts in a synergistic manner to induce antigen-specific antibody responses.

B-Lymphocytes↗
PubMed1985

Human B cell responsiveness to B cell growth factor after activation by phorbol ester and monoclonal anti-mu antibody.

The effect of phorbol ester on human B cell activation was examined. Picomolar to nanomolar concentrations of phorbol ester induced a high level of proliferation in small IgM-positive B cells isolated from peripheral blood by fluorescence-activated cell sorting. The addition of optimal doses of anti-mu antibody resulted in enhanced proliferation of phorbol ester-activated B cells. The addition of B cell growth factor (BCGF) to phorbol ester-activated B cells also resulted in a dose-dependent synergistic effect and maximal enhancement on day 3. BCGF activity could be absorbed with either phorbol ester- or anti-mu-activated B cells, but not with resting B cells, thus confirming the induction of functional BCGF receptor expression. Cell proliferation was not necessary for the induction of functional BCGF receptors. Phorbol ester was a more efficient inducer of BCGF receptor expression than was anti-mu antibody; gamma-interferon treatment had no effect. BCGF enhanced transferrin receptor expression by phorbol ester-activated B cells. The results suggest that phorbol ester-activated small B cells can be used to monitor BCGF activity, and this synergistic combination may be useful in establishing BCGF-dependent B cell clones in culture.

Absorption↗
PubMed1984

Regulation of human B-cell activation, proliferation, and differentiation by soluble factors.

This review describes a series of studies performed in our laboratory which have focused on the activation and subsequent proliferation and differentiation of human B lymphocytes. Utilizing polyclonal signals which activate B cells by interacting with their surface membrane Ig, we have examined the events in the transition of a resting B lymphocyte to an Ig-secreting cell. A major theme in these studies is the role of soluble factors in B cell proliferation and B cell differentiation. Specific B cell growth and differentiation factors are described. Data on their sources, biochemical characterization, and methods of assay are included. Additionally, the potential role of interleukin 2 in human B cell function is discussed. The recognition that B cells exist in a variety of activation states and that transition between different states is dependent upon different signals was the impetus for a series of studies which more precisely delineated these states and the signals involved. These findings and the observations from other investigators led to a proposed model of the sequential steps in a factor-dependent B cell differentiation pathway. This model is discussed and related to the mechanisms of T cell activation and growth. Finally, the effects of two pharmacologic agents, glucocorticoids and cyclosporin A, on human B cell function are described and discussed in the context of this model.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1984

Development of a human T-cell hybridoma secreting separate B-cell growth and differentiation factors.

A cloned human T-cell hybridoma (7D5) secreting B-cell growth factor (BCGF) and B-cell differentiation factor (BCDF) was established. Supernatant from this hybrid was capable of maintaining proliferation in anti-IgM-activated normal human B cells. In addition, the hybridoma supernatant induced differentiation and antibody secretion in Staphylococcus aureus Cowan I-stimulated B cells. No interleukin 2 was present in supernatant from this hybridoma. Molecular size of the hybridoma-derived BCGF and BCDF was determined by gel filtration chromatography. BCGF activity was present in the 20-kDa fractions, and BCDF activity eluted in the 30- to 35-kDa fractions. The isoelectric points of the factors, determined by chromatofocusing, were 6.6 for BCGF and 5.9 for BCDF. Finally, absorption experiments were performed using specific target cells. Phytohemagglutinin-stimulated T-cell blasts did not remove either BCGF or BCDF activity. Anti-IgM-activated B cells absorbed BCGF but not BCDF. In contrast, CESS cells removed BCDF but not BCGF. Thus, a human T-cell hybridoma secreting two distinct B-cell lymphokines was developed. Further immunochemical and functional studies of these immunoregulatory molecules should greatly enhance our understanding of the regulation of human B-cell function in normal and disease states.

B-Lymphocytes↗
PubMed1984

Sequential requirements for cell cycle progression of resting human B cells after activation by anti-Ig.

We have previously demonstrated that in vivo activated normal human B cells reflected differential sensitivity on the basis of cell size to either an activation signal delivered by anti-mu or a proliferative signal delivered by a monoclonal B cell growth factor (BCGF) produced by a human T-T hybridoma. In this manuscript, we have shown that by using an in vitro co-culture system of stimulation with anti-mu and BCGF, purified small (resting) B cells could be induced by anti-mu stimulation to express functionally active BCGF acceptor sites concomitant with RNA synthesis and cell enlargement. We have demonstrated that purified small B cells could be activated to increase both cell size and RNA synthesis within 8 hr of anti-mu stimulation. DNA synthesis by anti-mu-stimulated B cells began at 36 to 44 hr from initial stimulation only when BCGF was added to the culture. In addition, large B cells that had been incubated with anti-mu for 24 to 48 hr manifested significant incorporation of [3H]thymidine if BCGF was added to cultures. These data strongly suggest that anti-mu may induce the G0 phase B cells into the G1 phase and that BCGF may then push at least a subset of these G1 phase-B cells into the S phase. This experimental system may provide a useful model of normal human B cell activation and proliferation and may allow a more precise delineation of each phase of this cascade in the B cell repertoire.

Adolescent↗
PubMed1984

Characterization of monoclonal B cell growth factor (BCGF) produced by a human T-T hybridoma.

We previously demonstrated the development of a cloned human T cell hybridoma that secretes B cell growth factor (BCGF) in the absence of demonstrable interleukin 2 or B cell differentiation factor. Sephadex gel filtration chromatography demonstrated the m.w. of this factor to be 18 to 20K. The present studies were performed to further characterize the biochemical properties of the molecule and to determine its target cell specificity. Temperature stability studies showed the monoclonal BCGF to be stable at 37 degrees C for 12 hr and at 70 degrees C for 15 min; however, most (93%) of the activity was lost after incubation at 70 degrees C for 30 min. Aliquots of hybridoma supernatant were exposed to buffer solutions with variable pH with no diminution in activity over a pH range of 4.0 to 10.0 BCGF activity was not affected by 2-mercaptoethanol, neuraminidase, or nucleic acid denaturing enzymes. In contrast, all activity was destroyed by 10 M urea, trypsin, and chymotrypsin. Chromatofocusing demonstrated the isoelectric point of BCGF to be 6.3 to 6.6. Finally, absorption experiments demonstrated that BCGF activity was absorbed by large, activated B cells. Mitogen-stimulated T cell blasts, small resting B cells, and CESS cells failed to absorb BCGF activity from the hybridoma supernatant. These and future studies with purified monoclonal human BCGF should enhance our understanding of its immunochemical properties and of its role in the immunoregulation of human B cell responses.

Absorption↗
PubMed1984

Direct effects of a monoclonal B cell differentiation factor and of purified interleukin 1 on B cell differentiation.

We have previously described the presence of factors in mixed lymphocyte culture supernatants that induce activated but not resting human B cells to secrete Ig. In the present study, we describe the effects of a B cell differentiation factor in the supernatant (SN) of a T-T hybridoma (clone 7D5). We find that it induces Ig secretion by human B cells in the absence of T cells or monocytes. It acts only on activated B cells, because small (resting) B cells isolated by centrifugal counterflow elutriation do not respond to it, whereas the same cells do develop into Ig-secreting cells if activated in culture with Staphylococcus aureus Cowan I before exposure to SN 7D5. By using class-specific reagents in enzyme-linked immunosorbent assays, we found SN 7D5 to result in the secretion of significant amounts of IgM, IgG, and IgA. We also studied the effects of highly purified interleukin 1 on this differentiation process. Interleukin 1 by itself failed to induce Ig secretion by activated B cells, and its presence was not required for the induction of Ig secretion by SN 7D5. However, interleukin 1 consistently synergized with SN 7D5 in inducing Ig secretion by purified B cells.

B-Lymphocytes↗
PubMed1983

Selective suppression of an early step in human B cell activation by cyclosporin A.

The effect of cyclosporin A (CsA), a fungal metabolite with immunosuppressive properties, on the induction of human B cell proliferation and differentiation, has been described. CsA had a selective inhibitory effect on the activation phase of the cell cycle vs. the proliferation phase following preactivation of the cells. Cell enlargement and RNA synthesis of small resting B cells triggered by anti-mu were inhibited by addition of CsA (5-500 ng/ml). The inhibitory effect of CsA was found only when the drug was added within 24 h of initiation of culture. In marked contrast, once small B cells were activated by anti-mu, the resulting large, activated B cells could be induced to initiate DNA synthesis by incubation with B cell growth factor (BCGF), and addition of CsA (1-1,000 ng/ml) to the culture did not suppress this BCGF-induced B cell proliferation. Addition of CsA to cultures of B cells which had been preactivated with Staphylococcus aureus Cowan strain I (SAC) and were already proliferating did not suppress B cell differentiation factor (BCDF)-induced differentiation of these cells. Thus, these data indicate that CsA can be used as a pharmacologic tool to dissect out human B cell responses into two distinct steps: (a) the initial activation step induced by anti-Ig, which is characterized by cell enlargement, RNA synthesis, and expression of receptors for BCGF; and (b) the proliferative step induced by BCGF in these preactivated B cells that undergo DNA synthesis and can then go on to differentiate in the presence of BCDF. In this regard, CsA selectively suppresses an early step of human B cell activation and has little inhibitory effect on the subsequent factor-dependent proliferation and differentiation.

Adolescent↗
PubMed1983

Differential sensitivity of human B cell subsets to activation signals delivered by anti-mu antibody and proliferative signals delivered by a monoclonal B cell growth factor.

The present study demonstrates the minimal, optimal, and synergistic signals involved in the activation of normal human peripheral blood and tonsillar B cells to proliferation. Initial activation signals were delivered to B cells by low concentrations of anti-mu antibody which did not induce proliferation by themselves. However, marked synergy was seen when anti-mu antibody was added to cultures in the presence of monoclonal B cell growth factor (BCGF) obtained from a human T-T cell hybrid such that the B cells underwent substantial proliferation. This latter proliferation was seen without maturation into Ig-secreting cells, which indicates that the BCGF is not a differentiation signal but a signal that drives the cell up to but not beyond the proliferative phase. Of note was the fact that B cells reflected differential sensitivity on the basis of size to either the activation signal delivered by anti-mu antibody or the proliferative signal delivered by BCGF. BCGF directly stimulated the larger B cells in the normal tonsillar B cell repertoire to proliferate without the requirement for an in vitro activation signal, which indicates that the cells had already received some form of activation signal in vivo. Indeed, these cells expressed the 4F2 antigen found on activated but not resting lymphocytes. In contrast, the smaller tonsillar B lymphocytes did not express the 4F2 activation antigen and required activation by anti-mu antibody, which did not of itself induce proliferation, but which acted in synergy with BCGF for substantial proliferation of the B cells. These studies thus provide a useful model of human B cell activation, proliferation, and differentiation and allow a more precise delineation of each phase in this cascade.

Antibodies, Anti-Idiotypic↗
PubMed1983

Development of a human T-T cell hybridoma secreting B cell growth factor.

The success of long-term culture of normal human and murine B cells has been hampered by the limited availability of soluble factors capable of maintaining proliferation of activated B lymphocytes. Previous experiments using various culture-derived supernatants in a human system were unable to separate the activities of B cell growth factor (BCGF) and interleukin 2 (IL-2) by immunochemical means. Thus, purified factors with BCGF activity in the absence of IL-2 activity have not been available for study. In the present study, normal human peripheral blood T cells were fused with the hypoxanthine/aminopterin/thymidine-sensitive human T-leukemic cell line, CEM-6. Supernatants from the resulting hybrid cells were tested for the ability to maintain proliferation of normal human B cells in a recently described assay system for human BCGF. Hybrids demonstrating BCGF activity were cloned by limiting dilution. One hybrid clone, 2B11, continued to support proliferation of B cells in both long-term cultures and 6-d assays at a level significantly above that seen with conventionally produced growth factors. No IL-2 activity was found in the supernatant from hybrid 2B11. The hybridoma supernatant was fractionated by gel filtration, and maximum proliferation of B cells was supported by the 18-20,000 mol wt protein fraction. Thus, a human T-T cell hybridoma that has BCGF activity in the absence of any demonstrable IL-2 activity has been developed. Human T-T cell hybridomas secreting discrete immunoregulatory factors should prove to be powerful tools in dissecting the mechanisms of immunoregulation of human lymphocyte function.

B-Lymphocytes↗
PubMed1983

Biological effects of pion therapy beams: I. Cultured cells.

The results of cell killing by pion beams of different peak widths, ranges and sizes used in therapy are reported. Cultured hamster cells (V79) suspended in gelatin were used. The results indicate that: 1) there are no significant differences in cell-killing between pion beams of different ranges but of the same peak width; 2) there is a slight decrease in biological effectiveness with increasing peak width; and 3) the range-modulation functions used to produce uniform cell-killing are satisfactory for intermediate-range pion beams, but slight corrections may be required for shorter- and longer-range pion beams.

Animals↗
PubMed1983

The effects of interleukin 1 on human B cell activation and proliferation.

The precise role of B cell surface immunoglobulin (slg) in the activation of B cells is unclear at present. In particular, it is uncertain whether ligands interacting with the B cell slg suffice to induce proliferation, or simply induce a state of activation in which the B cell becomes responsive to growth factors made by accessory cells. We have examined the effects of two ligands, Staphylococcus aureus Cowan strain I (SAC) and antihuman mu chain (anti-mu), which interact with B cell slg on highly purified human peripheral blood and tonsillar B cells cultured at low cell concentrations. The effects on B cell proliferation of these ligands alone or in combination with highly purified interleukin 1 (IL 1) or a supernatant of a human T-T hybridoma containing a B cell growth factor (BCGF) were studied. SAC with its high cell wall content of protein A triggered maximal B cell proliferation which was not increased further by IL 1 or BCGF. High concentrations of soluble F(ab')2 fragments of goat anti-mu chain also induced significant B cell proliferation. Lower concentrations of anti-mu resulted in little or no B cell proliferation but activated the B cell to a state of responsiveness to both IL 1 and BCGF. IL 1 by itself had no effect on the proliferation of unstimulated B cells or on the proliferation of in vivo-activated B cells which responded to BCGF in vitro, but demonstrated clear synergy with low concentrations of anti-mu antibody. BCGF alone augmented the proliferation of unstimulated B cells, presumably by acting on B cells which had undergone some degree of activation in vivo. In addition, it showed marked synergy with anti-mu antibody, which resulted in proliferation similar in magnitude to that induced by SAC. This synergy was far greater than that seen between anti-mu antibody and IL 1, and the resulting proliferative response was only slightly increased by the presence of IL 1. We conclude that the importance of accessory cell factors for the initial rounds of B cell proliferation depends on the strength of the initial slg-mediated activation signal. When this is strong, the response is maximal and independent of accessory cells or accessory cell factors. When it is suboptimal, a moderate synergy is seen with IL 1 and a dramatic synergy with BCGF.

B-Lymphocytes↗
PubMed1982

Experience with continuous ambulatory peritoneal dialysis.

Thirty-one patients were trained for continuous ambulatory peritoneal dialysis (CAPD) over a 34-month period. Their mean age (42 +/- 14 years) did not differ from that of the total dialysis population. The training was conducted primarily on an outpatient basis by one registered nurse. The duration of treatment ranged from two to 34 months (median, 8.0 months). The technique failed in seven patients, in four because of peritonitis and in three because of catheter complications. Nine patients received renal transplants and one died while on CAPD. Dialysis was very effective with good biochemical control and excellent control of hypertension. Haemoglobin concentrations rose in 28 of the 31 patients (mean at 12 months, 2.0 g/L in 12 patients). Rehabilitation was comparable to that of home haemodialysis patients and superior to that of patients on hospital haemodialysis. The incidence of peritonitis decreased over the study period because of better patient selection, improved technology, and increased experience.

Adult↗
PubMed1981

Bacterial growth in ground beef prepared from electrically stimulated and nonstimulated muscles.

Ground beef samples prepared from electrically stimulated and nonstimulated biceps femoris and infraspinatus muscles were inoculated with Lactobacillus sp., Pseudomonas sp., Acinetobacter sp., or a mixture of Lactobacillus spp., Pseudomonas spp., Acinetobacter spp., Moraxella sp., Microbacterium thermosphactum, and Erwinia herbicola. There were no significant differences in growth of various bacteria in ground beef made from electrically stimulated and nonstimulated muscles.

Acinetobacter↗