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G L Warner

Publications and source records attributed to G L Warner.

24 records · Page 2Linked to original sources
PubMed1988

Immunoglobulins D and M mediate signals that are qualitatively different in B cells with an immature phenotype.

The CH family of murine B-cell lymphomas includes several members that are sensitive to growth inhibition when their membrane IgM (mIgM) receptors are cross-linked by anti-mu chain, anti-kappa chain, or anti-idiotypic antibodies. These lymphomas are IgM+, Ia+, and IgD +/- and resemble neonatal B cells in terms of their exquisite sensitivity to anti-IgM-mediated negative signaling as a model for tolerance induction. In this report, we describe the properties of one of these lymphomas, CH33, which had been transfected with a construct containing an allotypically different delta chain constant region and the heavy chain variable region fragment from S107 (T15 idiotype positive). This transfected cell line allowed us to investigate the possibility that membrane IgD (mIgD) and mIgM can mediate different signals. Our results show that the transfected cells retained their exquisite sensitivity to anti-IgM-mediated growth inhibition; however, crosslinking of IgD with anti-delta chain antibody did not inhibit their growth. Furthermore, even prolonged pretreatment with anti-IgD antibodies did not affect cell growth nor did it modulate the inhibitory effects of anti-IgM antibody. Moreover, identical results were obtained with clones of CH33 that express significant amounts of endogenous IgD. Thus, the failure of mIgD to deliver a negative signal does not reflect a defect in the transfected IgD but appears to be a general property of IgD in these cells. The mIgD was shown to mediate transmembrane signals because anti-delta chain treatment resulted in Ca2+ mobilization in transfected CH33 cells and capping of those receptors. We conclude that mIgD can mediate qualitatively different signals than mIgM can and that mIgD expression per se is not sufficient to change the functional phenotype of immature B cells.

Animals↗
PubMed1986

Cell surface and cell cycle analysis of metal-induced murine T cell proliferation.

The heavy metal cations Pb2+, Ni2+ and Zn2+ have previously been shown to induce T cell proliferation which required the presence of both T cells and Ia+ cells at the initiation of culture. This work has examined the ability of these metals to induce cell cycle entry as determined by acridine orange cell cycle analysis. Cell surface phenotype analysis, performed on splenocytes stimulated with optimum metal concentrations (100 microM), indicated that in vitro T cell recovery (growth and/or longevity) was enhanced by Pb2+, Ni2+, and Zn2+. Furthermore, simultaneous examination of cell surface phenotype and cell cycle progression (propidium iodide) indicated that the predominant cell type proliferating in response to these metals was Thy-1.2+. The metals differentially induced L3T4+ and Lyt-2+ cells to enter the cell cycle. The ability of various monoclonal antibodies to modulate metal-induced proliferation was examined. Anti-L3T4a, anti-I-A and anti-I-E blocked metal-induced proliferation. Anti-Lyt-2 only partially inhibited whereas anti-Lyt-1 was stimulatory. These results suggest that recognition of major histocompatibility complex-encoded class II molecules is required for the induction of proliferation by these metals (similar to the autologous mixed lymphocyte response).

Animals↗
PubMed1986

Fluorometric quantitation of cellular and nonprotein thiols.

A microfluorometric assay for thiols has been developed using the thiol-specific fluorochrome N-[4-(7-diethylamino-4-methyl-3-coumarinyl)phenyl]maleimide (CPM). The technique may be used to quantitate either cellular or plasma thiols over a range of 0.01 to 3.0 nmol and may be used with as few as 1-3 X 10(5) cells giving highly proportional and reproducible results. Values for nonprotein thiols obtained with this assay agree well with previous reports on glutathione (GSH) levels for both lymphocytes and plasma. Readings are determined with the aid of an automated fluorescence microplate reader which allows up to 96 samples, including standards, to be read at the same time. Cellular thiols accessible after lysis were also quantitated before and after treatment of intact cells with various thiol-reactive chemicals. Interestingly, HgCl2, bromoethanesulfonic acid, and N-ethylmaleimide differentially modified protein and nonprotein thiol levels.

Animals↗
PubMed1986

Stimulation of murine lymphocyte responses by cations.

The capacity of the heavy cations Pb, Ni, and Zn to modulate murine in vitro lymphocyte responses was examined. Pb and Ni (100 microM) were shown to enhance the in vitro plaque-forming cell (PFC) response to sheep red blood cells while 100 microM Zn had inhibitory effects. Each metal was able to stimulate the proliferation of murine splenocytes as determined by [3H]thymidine incorporation and autoradiography. The enhancing effect of the metals on the PFC response was observed whether the results were expressed on a per culture or a per cell basis, indicating an actual increase in B-cell differentiation. Both the PFC response and the proliferative response were shown to be sensitive to the type of medium employed (M-199 gave optimum results) and to the presence or absence of 2-mercaptoethanol. As in autologous mixed-lymphocyte responses peak proliferation occurred after Day 5 in culture, was cell density dependent, and required the presence of both T cells and Ia+ cells. Treatment of splenocytes with anti-Thy-1.2, anti-Lyt-1, or anti-L3T4 plus complement completely abrogated the proliferative response, indicating that a Lyt-1+, Lyt-2-, L3T4+ T-cell was required for the induction of proliferation. The data are consistent with the hypothesis that the metals are capable of modifying the immune response directed at self either by directly altering self constituents (class II) or by modulating the autologous T-cell response.

Animals↗
PubMedDate not supplied

BR96-doxorubicin conjugate (BMS-182248) versus doxorubicin: a comparative toxicity assessment in rats.

The toxicity of BMS-182248, an immunoglobulin (cBR96)-cytotoxic drug (doxorubicin) conjugate, was investigated in Sprague-Dawley rats at single intravenous doses of 508, 1,200, and 2,550 mg/m2 (conjugated doxorubicin doses of 14.7, 34.8, and 74 mg/m2, respectively) and compared to that obtained from administration of free doxorubicin at single doses of 33.6 and 72 mg/m2 (approximately equivalent to that contained in the 1,200- and 2,550-mg/m2 doses of BMS-182248, respectively). Necropsies were conducted on day 8, upon death/moribund sacrifice, or after an approximate 3-mo observation period following completion of treatment. Death/moribundity of all rats that received 72 mg/m2 and of 9 of 20 rats given 33.6 mg/m2 free doxorubicin were attributed primarily to delayed cardiotoxicity and glomerulonephropathy. With BMS-182248, death from glomerulonephropathy and cardiotoxicity occurred in only 4 of 20 rats given 2,550 mg/m2 (74 mg/m2 doxorubicin equivalent). No deaths or cardiotoxicity occurred in rats given 508 or 1,200 mg/m2 BMS-182248. Additional effects noted with either drug included testicular atrophy, axonal degeneration of sciatic nerve and nerve tracts of brain and spinal cord, teeth (incisor) abnormalities, thymic atrophy, bone marrow hypocellularity, splenic lymphoid and red-pulp depletion, and increased extramedullary hematopoiesis in the spleen and liver. Also noted were altered chief cells in the stomach, vacuolation of adrenal gland and corpora lutea in the ovary, uterine and seminal vesicle atrophy, ulceration and myocyte regeneration/degeneration in the tongue, increased osteoclasts and osteoblasts in bone, and lymphoid hyperplasia of mandibular lymph node. In general, these effects were more severe in doxorubicin-treated rats. All changes observed with BMS-182248 were considered primarily due to the effects of doxorubicin and were substantially less severe (most notably cardiotoxicity) compared to those produced by an equivalent amount of doxorubicin.

Animals↗