Subclasses of T cells with different sensitivities to cytotoxic antibody in the presence of anesthetics

The effects of conjugated linoleic acid supplementation on immune function in healthy volunteers

OBJECTIVE

To assess the effects of dietary supplementation using two isomeric blends of conjugated linoleic acid (CLA) on immune function in healthy human volunteers.

DESIGN

Double-blind, randomised, placebo-controlled intervention trial.

SUBJECTS AND INTERVENTION

A total of 55 healthy volunteers (n=20 males, n=35 females) were randomised into one of three study groups who received 3 g/day of a fatty acid blend containing a 50:50 cis-9, trans-11: trans-10, cis-12 CLA isomer blend (2 g CLA), and 80:20 cis-9, trans-11: trans-10, cis-12 (80:20) CLA isomer blend (1.76 g CLA) or linoleic acid (control, 2 g linoleic acid) for 8 weeks.

RESULTS

Supplementation with the 80:20 CLA isomer blend significantly (P< or =0.05) enhanced PHA-induced lymphocyte proliferation. CLA decreased basal interleukin (IL)-2 secretion (P< or =0.01) and increased PHA-induced IL-2 and tumor necrosis factor alpha (TNF(alpha)) production (P< or =0.01). However, these effects were not solely attributable to CLA as similar results were observed with linoleic acid. CLA supplementation had no significant effect on peripheral blood mononuclear cells IL-4 production, or on serum-soluble intercellular adhesion molecule-1 (sICAM-1) or plasma prostaglandin E2 (PGE2) or leukotreine B4 (LTB4) concentrations.

CONCLUSIONS

This study shows that CLA supplementation had a minimal effect on the markers of human immune function. Furthermore, supplementation with CLA had no immunological benefit compared with linoleic acid.

Laparotomy and laparoscopy differentially accelerate experimental flank tumour growth

BACKGROUND

Surgery depresses host tumoricidal activity and may increase tumour growth. This study compared the effects of laparoscopy with laparotomy on extraperitoneal tumour growth and immune function in a murine model.

METHODS

C57BL/6 female mice aged 8-10 weeks had tumours induced in the right flank (n=45) and were randomized to undergo halothane anaesthesia only, laparoscopy or laparotomy. Flank tumour volume was assessed over 10 days. A second group of animals (n=540) were randomized to undergo the same procedures and killed at 24, 48 and 96 h. Splenocytes were harvested for natural killer (NK) cell and lymphokine activated killer (LAK) cell cytotoxicity studies.

RESULTS

There was a significant increase in flank tumour growth in the first 48 h after laparotomy and laparoscopy compared with controls (P < 0.01). By 96 h the difference was only significant in the laparotomy group (P< 0.01). Both NK and LAK cell cytotoxicities were suppressed significantly (P < or = 0.03) from 24 h up to 96 h following laparotomy compared with control and laparoscopy groups. There was also a significant suppression in the laparoscopy group compared with controls in the first 48 h after operation (P < or = 0.02).

CONCLUSION

Extraperitoneal tumour growth was significantly accelerated after laparotomy and correlated with significantly suppressed NK and LAK cytotoxicity for at least 4 days after operation. Laparoscopy had a shorter, less profound effect on tumour growth and immune function.

Transmission of human T cell leukemia virus type I to sheep: antibody profile and detection of viral DNA sequences

Lambs were inoculated intraperitoneally with either 1.8 x 10(7) live peripheral blood cells from an HTLV-I-infected person (five lambs) or with 8 x 10(7) live cells from the HTLV-I-producing cell lines MT-2 (four lambs) or C10 MJ (five lambs). Four control lambs were inoculated with minimal essential medium supplemented with fetal calf serum. The animals were monitored during a period of 24 months. Beginning at 5 to 12 months after inoculation, four of the five lambs inoculated with the fresh HTLV-I-infected peripheral blood cells began to develop detectable levels of antibodies to a recombinant HTLV-I gp21env antigen, as determined by an enzyme-linked immunoassay (ELISA). The anti-gp21 antibodies persisted for the remaining observation period. These antibodies were not detected in the sera from the other sheep. Absorption and blocking experiments demonstrated the specificity of the gp21 reactivity. This reactivity was also confirmed by Western blot (WB). With the exception of the serum of an MT-2-inoculated sheep that formed a weak band with p19 by WB, none of the sera of the four gp21-positive sheep or of the other experimental sheep reacted with other structural or regulatory HTLV-I proteins, as determined by ELISA, WB, and radioimmunoassay. PCR analyses demonstrated the presence of the HTLV-I provirus in peripheral blood leukocytes of the four sheep showing antibodies to gp21env. The remaining sheep were negative. PCR analyses failed to detect BLV sequences in any of the experimental sheep. None of the sheep showed clinical abnormalities during the observation period. The potential value of the sheep model for studying atypical virus-host interactions in infected people is discussed.

In vitro characterization of a novel avian haemopoietic growth factor derived from stromal cells

To better define the role of the chicken haemopoietic microenvironment in supporting haemopoiesis, a continuous cell line was generated by RSV transformation of avian spleen stromal cells (SSL-1). Supernatants from this line were found to contain haemopoietic growth factor activity as measured by the ability to induce proliferation and differentiation of precursor cells present in embryonic and post-hatched haemopoietic tissues. Comparison of cultures grown in the presence of cMGF and SSL-1 conditioned media (CM) revealed that both cytokine sources induced similar types of cell populations. Both sources supported the proliferation of predominantly macrophage-like cells based on colony morphology, differential staining, non-specific esterase staining, and phagocytosis activity. Interestingly, SSL-1 does not express any message for cMGF, nor does it secrete any IL-2 or interferon activities suggesting that the growth factor activities seen in SSL-1 are novel.

Efficacy of traditional Chinese herbal therapy in vitro. A model system for atopic eczema: inhibition of CD23 expression on blood monocytes

Recently, there has been growing interest in the use of traditional Chinese herbal therapy (TCHT) decoctions for the treatment of atopic eczema (AE). The mode of action of this treatment is still unknown, and in order to investigate this we have analysed the effect of an extract of these herbs (TCHTE) on interleukin 4 (IL-4)-induced CD23 expression on peripheral blood monocytes from non-atopic subjects. We found that TCHTE inhibited CD23 expression up to 60% (P < 0.001), whereas the placebo extract had no significant effect on CD23 expression. This inhibition was dose-dependent, and TCHTE was effective at a concentration of 250 micrograms/ml (P = 0.001). If TCHTE or placebo was added after IL-4, the action of TCHTE could still be seen at 12 h. This inhibition was not due to cell death, as peripheral blood mononuclear cells (PBMCs) cultured with TCHTE or placebo at a concentration used in these experiments had a similar viability to control cultures. Down-regulation of the low affinity receptors for IgE on antigen-presenting cells in patients with AE may contribute to the benefit observed following treatment with TCHT.

Flow cytometric analysis of surface major histocompatibility complex class II expression on human epithelial cells prepared from small intestinal biopsies

A technique for preparing viable, single cell suspensions of the epithelial layer of small intestinal tissue obtained endoscopically is described. Constant agitation of four biopsies for 60 min in the presence of chelating and reducing agents gave yields of 1.2-6.7 x 10(6) cells, of which 11-30% were intraepithelial lymphocytes (IEL). Passage through a nylon wool column removed dead cells. This preparation was suitable for flow cytometric analysis. Using this technique, surface MHC class II molecule expression was studied in 14 patients with normal small intestinal mucosa. Fluorescence labelling of these cells showed strong HLA-DR expression by epithelial cells (EC), DP was expressed less strongly, while little DQ expression could be detected. This technique demonstrates that small intestinal biopsies taken during routine endoscopy can yield adequate numbers of viable epithelial cells to perform flow cytometric analysis.

Occupancy of the cancer cell urokinase receptor (uPAR): effects of acid elution and exogenous uPA on cell surface urokinase (uPA)

The development of a simple, sensitive fluorimetric assay for the measurement of cell surface-associated urokinase plasminogen activator (uPA) on viable, adherent HCT116 cells in microtitre plates, after a preincubation with purified human plasminogen is described. The assay determines plasmin activity by the cleavage of H-D-Val-Leu-Lys 4-aminomethyl coumarin under near physiological pH and ionic conditions with a sensitivity in the range of 5-100 mIU uPA/well at excitation 355 nm and emission 460 nm. Plasmin generated during the assay converted all cell-surface sc-uPA to tc-uPA, allowing the determination of total uPA activity. Inhibitor studies (PAI-2, amiloride or Glu-Gly-Arg chloromethylketone) confirmed the specificity of the uPA assay. Removal of these agents prior to assay allowed determination of the cell surface sc-uPA:tc-uPA ratio. Cell surface activity was only partially removed by acid elution. This corresponded with the loss of a number of proteins and uPA-containing species as detected by SDS-PAGE, gelatin enzymography and Western blotting. Although the major protein species eluted had a M(r) of 55 kDa, reacted with a commercial anti-human uPA mAb and correlated with the main lytic zone, other higher M(r) species were also eluted from HCT116 cells. Exogenous uPA increased cell-surface activity markedly on cells previously treated with acid. Following acid elution, cell surface uPA activity was restored after 30h in culture suggesting either de novo synthesis or release of pre-formed uPA with subsequent secretion and binding to uPAR. The assay has enabled studies on adherent cells to address questions about the regulation and expression of cell-surface uPA.

Detection of, and anti-collagen antibody produced by, CD5-positive B cells in inflamed gingival tissues

This study was performed to investigate the frequency and distribution of CD5-positive (CD5+) B cells in inflamed gingival tissues using flow cytometric and immunohistochemical analyses. The ability of CD5+ B cells to produce anti-type I collagen antibody was also examined. CD5+ B cells expressed "low" fluorescence intensity in the peripheral blood of both healthy subjects and patients with adult periodontitis. However, in inflamed gingival tissues the intensity of this surface marker was high. The percentage of B cells bearing CD5 surface marker was statistically higher in gingiva than in peripheral blood obtained from both the patients and healthy subjects. These CD5+ B cells were observed in gingival subepithelial connective tissues from the bottom to the middle of the periodontal pocket. This area showed destruction of collagen fibers and dense cell infiltrations. Anti-collagen IgG antibody level in patients' gingival crevicular fluids (GCF) was higher than that in sera from healthy subjects, and slightly higher than in autologous sera. IgM anti-collagen antibody in GCF was lower than in autologous sera and in sera from healthy subjects. EBV-transformed CD5+ B cells produced considerably more IgM and IgG antibody to collagen than CD5- B cells. Therefore CD5+ B cells may contribute to the pathogenesis of inflamed gingival tissues.

Non-radioactive detection of immunoglobulin and T cell receptor gene rearrangement in acute lymphoblastic leukaemia

Rearrangements of the heavy chain immunoglobulin gene and T cell receptor beta gene were investigated in 25 patients suffering from precursor B cell acute leukaemia and six patients suffering from T cell acute leukaemia using biotinylated DNA probes. All precursor B acute leukaemia patients had IgH gene rearrangements and 63% of those studied also had TCR beta gene rearrangements. All T cell acute leukaemia patients had TCR beta gene rearrangements and germline IgH configuration. Dilution experiments indicated that DNA from leukaemic cells representing 1-2% of a tested sample could be detected using this technique which compares favourably to radioactive DNA probes.

Mouse lymphoma cells that undergo interphase death show markedly increased sensitivity to radiation-induced DNA double-strand breakage as compared with cells that undergo mitotic death

The relationship between radiation-induced DNA double-strand breakage (dsb) and reproductive death (clonogenicity) for two mouse lymphoma cell lines was compared with that for the fibroblast-like hamster cell line V79. One of the lymphoma lines (STRij-4-2.2), which undergoes rapid disintegration following cytotoxic insult, showed extreme sensitivity to gamma-ray or DNA-associated 125I decay-induced DNA dsb (7 +/- 1 125I decays per clonogenic lethal event). Surprisingly, the other lymphoma line (WEHI-22.1), which does not undergo rapid disintegration, was also much more sensitive to DNA dsb than were V79 cells (17 +/- 1 versus 61 +/- 2 125I decays per clonogenic lethal event). Ultrastructure, DNA degradation, and flow cytometric cell cycle data suggested that both lymphoma cell lines may undergo interphase death, but that the induction of this process in WEHI-22.1 may depend upon blockage in the G2 phase. It is concluded that there are marked differences between the radiation responses of lymphoma and fibroblast lines, that there may be different forms of radiation-induced interphase death, and that the low number of DNA dsb required to produce a clonogenic lethal event in cells undergoing interphase death could explain the radiosensitivity of organs such as ovary, testis and thymus.

1,25-Dihydroxyvitamin D3 modulates the effects of interleukin 2 independent of IL-2 receptor binding

Previous studies have shown that 1,25-dihydroxyvitamin D3 (calcitriol) is a macrophage-derived cytokine and a potent inhibitor of IL-2 and interferon-gamma (IFN-gamma) production and T lymphocyte proliferation. The growth inhibitory effect of calcitriol is only partially reversed by IL-2 addition, suggesting IL-2 independent effects. In this report we characterize the IL-2-independent effects of calcitriol on lymphocyte activation. Calcitriol inhibited cellular transition from early to late G1 (G1A-G1B transition) in both the absence and presence of IL-2. Exogenous IL-2 did not increase either IFN-gamma production or transferrin receptor (TfR) expression in the presence of calcitriol despite increases in cell entry into late G1 and proliferation. Calcitriol treatment reduced TfR expression by activated T lymphocytes independent of their location in the cell cycle, further suggesting its independence from IL-2-mediated events. Combinations of rIL-2 and rIL-4 did not reverse calcitriol-dependent inhibition of proliferation and TfR expression to any greater degree than rIL-2 alone. Northern blot analysis demonstrated the decrease in IFN-gamma and TfR mRNA accumulation with calcitriol treatment was unaffected by exogenous IL-2. In contrast, IL-2R mRNA and protein were increased by IL-2, with superinduction in the presence of calcitriol, demonstrating that the lack of effect on IFN-gamma and TfR was not due to IL-2 insensitivity. Moreover, equivalent numbers of high-affinity IL-2R were expressed by both control and calcitriol-treated T lymphoblasts. Thus, lectin-activated T lymphocyte responsiveness to IL-2, as measured by IL-2R expression and proliferation, can be partly to completely dissociated from IFN-gamma production and TfR expression in the presence of calcitriol. Finally, IL-2-induced proliferation of unstimulated mononuclear cells and purified T lymphocytes was inhibited by calcitriol. These data indicate that local production of calcitriol by activated macrophages is capable of regulating T lymphocyte activation not only through suppression of IL-2 production, but also through additional mechanism(s), that are mediated at a post-IL-2R level.

Generation of IL-1-like activity in response to biomedical polymer implants: a comparison of in vitro and in vivo models

Of the many factors determining host biocompatibility responses to implanted biomedical polymers, the cellular interactions at the tissue/material interface have been recognized to be some of the most important. The present study has combined results both from an in vitro cell culture system and from an in vivo animal model to examine this host response. In vitro results suggest that a variety of polymer materials can differentially activate human monocytes to produce a protein(s) having different biological activities. The polymers tested induce the production of the regulatory inflammatory protein interleukin 1 as well as a factor that enhances fibroblast proliferation and collagen synthesis. The observed activities of these factors appear to be related but not identical, and are dependent upon the specific polymer. Evaluation of exudate and tissue responses to these same polymer materials in an in vivo model are also presented. Both in vitro and in vivo results support the hypothesis that monocyte/macrophage activation with subsequent synthesis of regulatory factors such as interleukin 1 plays a significant role in determining the host response to biomedical polymer implants.

In vitro stimulation of fibroblast activity by factors generated from human monocytes activated by biomedical polymers

Biomedical polymers used in constructing implantable artificial devices may affect host responses to the material and ultimately contribute to the success or failure of a device via mechanisms of cell-polymer interactions. Human peripheral blood monocytes (MO) cultured in the presence of several such biomedical polymers released factors that stimulated fibroblast proliferation and/or collagen synthesis. The factors that stimulated fibroblast proliferation were differentially released from monocytes cultured in the presence of Dacron, polyethylene, expanded polytetrafluoroethylene (ePTFE), polydimethylsiloxane, and polystyrene (control). Supernatants obtained from monocytes cultured in the presence of Biomer, a segmented polyetherurethane, were unable to stimulate fibroblast proliferation. However, supernatants from all cultures, including MO-Biomer cultures, were able to induce collagen production from the same target fibroblasts. These same supernatants also were shown to contain interleukin 1 (IL1) activity. Neutralization of the fibroblast stimulatory potential (FSP) activity with antibodies directed against human IL1 and human PDGF demonstrated that IL1 and not PDGF was responsible for the FSP activity. Results of this study show that by affecting macrophage activation, different biomedical polymers can affect host biocompatibility responses by altering fibroblast proliferation and function.

Expression and regulation of the HLA-DR antigen on circulating monocytes isolated from patients with rheumatoid arthritis

Using a modified radioimmunoassay, surface labeling of HLA-DR antigens on monocytes revealed reduced densities in patients with active rheumatoid arthritis (RA) (P less than 0.001) and in gold-treated patients (P less than 0.01) versus normal controls. Significant enhancement of DR antigen expression (P = 0.01), with values similar to those of normal monocytes, occurred in patient monocytes preincubated at 37 degrees C overnight, but not in monocytes preincubated at 4 degrees C. This suggested that a temperature-dependent metabolic process is required to enhance antigen expression. The addition of cycloheximide totally inhibited the enhancement of DR antigen density. Incubation of monocytes with exogenous prostaglandin E2 (10(-5)M final concentration) caused a reduction of DR densities on control and on RA monocytes, although this decrease was more marked in the controls. Addition of indomethacin did not affect DR antigen levels on control monocytes, but greatly enhanced the expression of DR antigens on RA monocytes. When HLA-DR antigen levels were estimated in detergent-solubilized membrane preparations, monocytes from patients with active RA demonstrated normal-to-increased densities compared with control monocytes. Thus, although RA monocytes possess a normal ability to synthesize DR molecules, surface expression of these molecules is inhibited; this inhibition may be mediated by prostaglandin E2 acting as a negative suppressive signal.

A carcinoembryonic antigen-directed immunotoxin built by linking a monoclonal antibody to a hemolytic toxin

Hybrid molecules prepared by linking toxins to monoclonal antibodies (MAbs) are cytotoxic to cells bearing the target antigen. The toxin most widely used has been the plant toxin ricin as the toxic component, which inhibits protein synthesis at the ribosome level. Immunotoxins based on membrane-active, hemolytic toxins can be a useful alternative when directed towards antigens which do not mediate internalization, as is the case for most carcinoma antigens. We present an alternative for toxic components using a hemolytic toxin acting at the membrane level, due to its phospholipase activity. The hemolytic toxin (HT), isolated from the sea anemone Stoichactis helianthus, has been conjugated to a MAb directed against carcinoembryonic antigen (CEA), by means of an artificial disulphide bridge. The hybrid alpha CEA-HT exhibits no hemolytic activity unless it is reduced. It is toxic for cells (MDA-MB-134) expressing CEA and not toxic for cells (MDA-MB-231) not bearing CEA. An excess of free antibody reverses toxicity.

Characterization of biomedical polymer-adherent macrophages: interleukin 1 generation and scanning electron microscopy studies

Macrophage activation following attachment to biomedical polymers was studied using two systems of analysis. Supernatants generated by human peripheral blood monocytes cultured on the surface of several different biomedical polymers were evaluated for the presence of the secreted regulatory protein interleukin 1 (IL1). In addition, each cell-polymer culture surface was subjected to scanning electron microscopy for gross morphological evaluation. Results indicate that, although all materials were efficient in the attachment and activation of cells, the panel of polymers showed a differential capacity in attachment and activation of monocytes. Dacron and polyethylene surfaces had a greater density of cells showing morphology indicative of activation, corresponding to elevated levels of IL1 in these cultures. Biomer and polydimethylsiloxane surfaces showed fewer activated cells and had lower IL1 levels in culture. Expanded polytetrafluorethylene resulted in intermediate levels of IL1 and attached cells showing activated morphology.

Encephalitozoon cuniculi: quantitation of parasites and evaluation of viability

Two methods (manual and automated) for quantitation of viable versus dead Encephalitozoon cuniculi are reported. The manual method uses ethidium bromide and acridine orange to stain dead and viable organisms, respectively. The stained organisms are visually differentiated with the aid of a fluorescence microscope. The automated method uses propidium iodide to stain dead parasites, which are differentiated from viable unstained parasites with the aid of a flow cytometer. An automated cell counter (Coulter Counter) was used to count rapidly large numbers of samples and to improve the sensitivity of counting low concentrations of parasites. These methods will enhance investigators' abilities to conduct quantitative experiments on host defense mechanisms against E. cuniculi.

Human monocyte/macrophage activation and interleukin 1 generation by biomedical polymers

In vitro cell culture techniques were used to evaluate the effect of several clinically significant biomedical polymers on monocyte activation and Interleukin 1 (IL1) production. Isolated human peripheral blood monocytes were cultured in the presence of a panel of five biomedical polymers routinely used in a variety of clinical applications: Polyethylene (PE), silica-free poly-dimethylsiloxane (PDMS), woven Dacron fabric, expanded polytetrafluoroethylene (ePTFE) and the segmented polyurethane, Biomer. Monocytes generated IL1 in the presence of all five materials. Maximal levels of IL1 were generated at 24 h in monocyte-polymer cultures supplemented with serum and additionally stimulated with lipopolysaccharide (LPS). No difference was observed due to serum source. Results from cultures supplemented with fetal bovine serum were not significantly different from those obtained with human serum supplemented cultures. The thymocyte proliferative activity generated by monocytes in the presence of these biomedical polymers was neutralized by a specific polyclonal anti-IL1 antiserum. Statistically significant differences in IL1 production were observed between polymers, allowing their classification according to reactivity into high (Dacron, PE), intermediate (ePTFE) and low (Biomer, PDMS) reactive groups.

Expression of CD 21, CD 22, and the mouse erythrocyte receptor on peripheral B lymphocytes in rheumatoid arthritis

The expression of the B cell antigens, CD 21, CD 22, and the mouse erythrocyte receptor (MER), on peripheral mononuclear cells (PMC) in 61 patients with rheumatoid arthritis (RA) and in 25 patients with various other forms of rheumatic disease was studied. Patients with RA showed significantly more peripheral B cells than control patients, whereas there was no difference between patients with RA and controls in resting B cells expressing the MER or resting and activated B cells expressing CD 21. Patients with active RA had significantly less MER positive and more CD 21 positive B cells than patients with inactive disease. The relation between disease activity and expression of MER and CD 21 was independent of drug treatment or production of classical rheumatoid factor. These data may be interpreted as a sign of B cell activation in RA. In addition, patients with seronegative RA receiving gold treatment showed significantly more MER positive cells than patients receiving different drugs, whereas patients receiving non-steroidal anti-inflammatory drugs (NSAIDs) alone had significantly more CD 21 positive cells. This may be the result of different immunomodulating effects of drugs on B cell subsets.

Folate transport in enterocytes and brush-border-membrane vesicles isolated from the small intestine of the neonatal goat

1. The uptake of 5-methyltetrahydrofolate (MTHF) and folic acid (pteroylmonoglutamate) by enterocytes and brush-border-membrane vesicles prepared from the small intestine of the 6-d-old male goat was determined using a rapid-filtration assay. 2. Both MTHF and folic acid were taken up by membrane vesicles at 25 degrees and enterocytes at 37 degrees by a pH-dependent mechanism with maximum uptake when the pH of the incubation medium was 5.0. 3. Experiments in which the osmotic pressure of the medium was raised in successive increments with the non-absorbable sugar cellobiose indicated that transport rather than membrane binding was the main component of uptake. 4. Experiments at pH 5.0 showed that uptake of MTHF and folic acid was saturable and that the characteristics of folate transport were similar in both tissue preparations: (a) transport rates of both MTHF and folic acid were constant during the first 1-2 min for a given folate concentration, then declined to reach a steady-state in 10-30 min; (b) initial velocities of transport of MTHF and folic acid increased in proportion to their concentrations up to 7-10 microM, but the rate of increase slowed thereafter until saturation was reached at 20-25 microM (Km for brush-border-membrane vesicles 40.8 and 62.9 microM, Km for enterocytes 50.9 and 55.2 microM for MTHF and folic acid respectively). Values of Vmax for membrane vesicles (pmol/mg protein per min) were 46.5 MTHF or 40.3 folic acid; enterocytes Vmax (pmol/10(7) cells per min) 15.9 MTHF or 30.6 folic acid; (c) uptake of MTHF and folic acid by brush-border-membrane vesicles and enterocytes measured under steady-state conditions approached saturation at 50 microM for each analogue (Km for membrane vesicles 58.1 and 55.2 microM, Km for enterocytes 43.1 and 49.4 microM for MTHF and folic acid respectively; Vmax for membrane vesicles 49.7 and 77.8 pmol/mg protein, for enterocytes 52.8 and 54.7 pmol/10(7) cells for MTHF and folic acid respectively). 5. It was concluded that transport of MTHF and folic acid was by a similar pH-dependent mechanism both in brush-border-membrane vesicles and in intact enterocytes. At pH 5.0, transport involved a saturable carrier-mediated process located in the brush-border membrane.

Detection of the lethal effects of T-2 mycotoxin on cells using a rapid colorimetric viability assay

A colorimetric method of determining cell viabilities in cultured cells is described. The system is based on the ability of mitochondrial enzymes in live but not dead cells to chemically reduce a tetrazolium salt (MTT) into a colored formazan dye which can be detected at 570 nm using a multiwell scanning spectrophotometer. 48 h Chinese hamster ovary (CHO) cell cultures are used in the assay and the amount of colored product formed is directly proportional to cell number over a range of 0.39-12.5 X 10(4) cells/ml. The cytotoxic effects of T-2 mycotoxin can also be detected colorimetrically using this method. The toxin dose which inhibits formazan formation (50% endpoint = 14-16 ng/ml) is very comparable to that which inhibits cell viability (17 ng/ml), or protein and DNA synthesis (10 ng/ml). This system also works well with mitogen-stimulated primary lymphocyte cultures but these cells exhibit a much more sensitive response to T-2 effects having a 50% inhibition endpoint of 2 ng/ml. The assay is rapid to perform and gives a high degree of precision and could serve as a valid alternative to viability assays currently in use.

Characterization and quantification of solubilised HLA-DR antigens from circulating human monocytes using an immunoblotting procedure

An immunoblotting technique was modified to detect and biochemically characterize HLA-DR antigens expressed on circulating human monocytes. Membrane proteins of peripheral blood monocytes were solubilised using the mildly anionic detergent, sodium deoxycholate. These solubilised proteins were resolved by SDS-PAGE and transferred electrophoretically to nitrocellulose. The HLA-DR antigen was detected using a polyclonal antiserum and two monoclonal anti-HLA-DR antibodies. Both immunoperoxidase and 125I autoradiography techniques were used for visualisation of the antigen. The resolution of HLA-DR reactive material was increased when proteins were renatured with 4M urea after blotting. Immunoprobing of a sample of solubilized membrane proteins showed three bands of HLA-DR antigenic reactivity at molecular weights 65kDa, 55kDa and 46kDa. After storage at -70 degrees C for 2 months, only the 46kDa HLA-DR antigen band was detectable. Nonetheless, the 2-chain HLA-DR molecule was found to be an extremely stable complex which could not be dissociated by boiling in sample buffer containing 5% 2-mercaptoethanol and 2% SDS. A stronger reducing agent, 25 mM dithiothreitol, was required to split the HLA-DR molecule into its alpha and beta subunit chains. Finally, in a study of circulating monocytes from normal subjects, the immunoblotting technique was shown to quantitate solubilised HLA-DR antigen in a reproducible manner.

The simultaneous presentation of peripheral T-cell lymphoma and hairy cell leukemia

A patient who presented simultaneously with B hairy cell leukemia (HCL) and peripheral T-cell lymphoma (PTL) is described. The diagnoses of the two neoplasms were made by standard morphologic and cytochemical study and confirmed immunologically. There was no evidence of overlap in markers to suggest that they arose from a single clone of malignant cells. It is suggested that the simultaneous occurrence of the two neoplasms in the same patient reflects an underlying predisposition to the development of neoplasia in HCL.

Na+-dependent transport of taurine by membrane vesicles of neuroblastoma x glioma hybrid cells

The transport of taurine into membrane vesicles prepared from neuroblastoma x glioma hybrid cells 108CC5 was studied. A great part of the taurine uptake by the membrane preparation is due to the transport into an osmotically sensitive space of membrane vesicles. Taurine uptake by membrane vesicles is an active transport driven by the concentration gradient of Na+ across the membrane (outside concentration greater than inside). The Km value of 36 microM for Na+-dependent taurine uptake indicates a high-affinity transport system. The rate of taurine transport by the membrane vesicles is enhanced by the K+ gradient (inside concentration greater than outside) and the K+ ionophore valinomycin. Taurine transport is inhibited by several structural analogs of taurine: hypotaurine, beta-alanine, and taurocyamine. All these results indicate that the taurine transport system of the membrane vesicles displays properties almost identical to those of intact neuroblastoma X glioma hybrid cells.

Calcium ionophore-induced changes in HCO3- secretion and Cl- absorption in turtle bladder: relation to action of 3-isobutyl-1-methylxanthine

The calcium ionophore A23187 stimulates luminal alkalinization and inhibits Cl- absorption in short-circuited urinary bladders of postprandial or alkalotic turtles. The ionophore appears to mimic the action of the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) by its similar effects on HCO3- secretion and Cl- absorption and by increasing cytosolic cAMP levels of isolated bladder epithelial cells. However, only A23187 (or ionomycin), but not IMBX or cAMP, elevated cytosolic Ca2+ of aequorin- or quin2-loaded cells. Since A23187, but not IBMX or cAMP inhibits luminal acidification, we postulate that cytosolic Ca2+ regulates the acidification process by a cAMP-independent mechanism and controls HCO3- secretion as well as Cl- absorption, at least in part, via cAMP-mediated pathways.

In vitro effect of synthetic pyocyanine on neutrophil superoxide production

Pyocyanine, a low-molecular-weight phenazine pigment produced by Pseudomonas aeruginosa, has previously been shown to strongly inhibit human lymphocyte blastogenesis. We now report that synthetic pyocyanine can also affect the generation of superoxide by human peripheral blood polymorphonuclear leukocytes (PMNs) in a dose-dependent manner. Superoxide production by PMNs stimulated with phorbol myristate acetate (PMA) was measured in the presence and absence of pyocyanine, phenazine, and trifluoperazine, a phenothiazine of similar chemical structure to the phenazine pigments. Pyocyanine at 50 microM inhibited superoxide production to 28.9 +/- 2.8% of PMA control values, whereas at the lower concentration of 1 microM, the production of superoxide was significantly enhanced (203 +/- 31.7% of PMA control values). Phenazine, the tricyclic parent compound of pyocyanine, had only a minor effect. Trifluoperazine had a marked inhibitory effect on superoxide generation at concentrations above 1 microM. None of the compounds induced superoxide generation in the absence of PMA. Pyocyanine at all concentrations, unlike phenothiazines, had very little effect on the release of neutrophil granule enzymes. The effect of P. aeruginosa phenazine pigments on polymorphonuclear phagocytes is of significance, since inhibition of host PMN function at sites of infection could result in ineffective bacterial killing, whereas enhanced PMN function could lead to greater tissue damage. These two possibilities are not mutually exclusive and may coexist depending on local pyocyanine concentrations.

Effects of cardiotoxin D from Naja naja siamensis snake venom upon murine splenic lymphocytes

Cardiotoxin D from Naja naja siamensis is cytotoxic to T-lymphocytes above 150 femtomoles/10(6) cells. Equivalent lysis of macrophages or B-lymphocytes requires at least 1000 times more toxin. Reduction and carboxamidomethylation of cardiotoxin D does not effect T cell lysis. At higher toxin concentrations, 50% T-cell lysis occurs within 10 min. Splenocytes cultured with mitogens are up to five times more susceptible to toxin than unstimulated cells. Cardiotoxin D may directly disrupt the plasma membrane, since lysis is unaltered at 4 degrees C.

Comparison of methods for freezing interleukin-dependent murine cell lines

Various methods for freezing several interleukin-dependent murine cell lines have been compared and were shown to differ in their efficacy from line to line. An interleukin-2-dependent cell line, T572.C5, which was more sensitive to dimethylsulfoxide (DMSO) than the other cell lines, was the most difficult to freeze in a viable state. In order to define better conditions for freezing, the effects of the changes in freezing rates and concentrations of DMSO and of the addition of Ficoll were determined. The optimal freezing rates and DMSO concentrations varied from line to line. The addition of Ficoll increased the viability in some, but not all, cell lines, depending on the freezing conditions used. Thus, the optimal conditions for freezing interleukin-dependent cell lines varied from line to line. In general, the direct freezing procedure was better than the styrofoam-box freezing method. Although programmed freezing under direct temperature control was the most suitable among the freezing procedures examined, unprogrammed procedures also were of practical use.

Supravital fluorescent staining of the corneal endothelium with acridine orange and ethidium bromide

We investigated the combined fluorescent dyes acridine orange (AO) and ethidium bromide (EB) for corneal endothelial evaluation. Both dyes intercalate with DNA and RNA and are mutagenic at high concentrations. Optimum differential staining was obtained after 5 minutes exposure to 1 microgram/ml of each dye. Electron microscopy confirmed that the dye combination simultaneously identified both viable and nonviable cells. Swelling of perfused dog corneas for 3 hours after exposure to both dyes for 5 minutes was not increased. Exposure to visible light from a fluorescence microscope for 2-5 minutes caused increased corneal swelling and abnormal intercellular junctions by electron microscopy in paired dog corneas stained for 5 minutes with either AO or EB. The addition of 10% calf serum to the staining and observation media decreased the toxic effect of AO/EB and light seen by specular microscopy and by electron microscopy. Human corneas exposed to AO and EB were not mutagenic in the Salmonella/microsome assay. These results indicate that AO and EB, 1 microgram/ml, provide a rapid identification of both viable and nonviable corneal endothelial cells. When the corneas are exposed to light, however, the dyes are toxic; this toxicity is decreased by the presence of 10% calf serum in the staining and observation media.

Experimental induction of rheumatoid factor and joint lesions in rabbits after intravenous injections of killed bacteria

Rabbits receiving repeated intravenous injections of killed bacteria (Escherichia coli or Bacillus subtilis) developed IgM rheumatoid factor which reacted with autologous heat-aggregated IgG. In addition, 5/7 'Old English' and 7/8 'Sandy Lop' rabbits receiving killed E. coli developed rheumatoid-like synovial lesions. 'Old English' rabbits developed lesions of a more severe nature. Three of eight 'Sandy Lop' rabbits injected with killed B. subtilis had high levels of rheumatoid factor but only mild joint lesions.

Mitogen-induced phosphorylation of cytosolic proteins in rabbit T- and B-lymphocytes

The addition of anti-immunoglobulin (anti-Ig) to purified rabbit B-cells or concanavalin A (Con A) to purified rabbit T-cells within minutes resulted in the phosphorylation of a number of cytosolic proteins. Two-dimensional (2-D) electrophoresis and autoradiography of 32P-labeled cell sonicates was used to identify proteins whose phosphorylation was enhanced by these mitogens. Two proteins, pp58 and pp90, were phosphorylated 1.5 min after addition of anti-Ig to B-cells. Four other proteins, pp60, pp65, pp67 and pp95, were phosphorylated at later times. Three of these proteins were also phosphorylated after addition of Con A to purified T-cells. These phosphoproteins do not correspond to any previously described cytoplasmic proteins. Although all of these phosphoproteins were present in the cytosolic fraction, pp58 may be associated with the cytoskeleton. Protein pp58 is also distinguished from the rest by its absence from 2-D gels run under non-reducing conditions. Treatment of the B-cells with F(ab')2 fragments of anti-Ig stimulated phosphorylation but Fab' fragments did not--indicating that receptor cross-linking is required to induce phosphorylation. Both pp58 and pp90 contained phosphoserine, but neither phosphothreonine nor phosphotyrosine. Quantitatively the 32P-labeling of pp58 was 2.7-fold over background at 10 min after anti-Ig addition. The identification of these phosphoproteins, which may play a role in activational cascades or in cytoskeletal rearrangements, hopefully will help to clarify the interrelationships between cyclic nucleotide dependent and independent kinases in lymphocyte activation.

Topography, purification and characterization of thyroidal NAD+ glycohydrolase

Subcellular fractionation of bovine thyroid tissue by differential pelleting and isopycnic gradient centrifugation in a zonal rotor indicated that NAD(+) glycohydrolase is predominantly located and rather uniformly distributed in the plasma membrane. Comparison of NAD(+) glycohydrolase activities of intact thyroid tissue slices, functional rat thyroid cells in culture (FRT(l)) and their respective homogenates indicated that most if not all of the enzyme (catalytic site) is accessible to extracellular NAD(+). The reaction product nicotinamide was predominantly recovered from the extracellular medium. The diazonium salt of sulphanilic acid, not penetrating into intact cells, was able to decrease the activity of intact thyroid tissue slices to the same extent as in the homogenate. Under the same conditions this reagent almost completely abolished NAD(+) glycohydrolase activity associated with intact thyroid cells in culture. The triazine dye Cibacron Blue F3GA and its high-M(r) derivative Blue Dextran respectively completely eliminated or caused a severe depression in the NAD(+) glycohydrolase activity of FRT(l) cells. The enzyme could be readily solubilized from bovine thyroid membranes by detergent extraction, and was further purified by gel filtration and affinity chromatography on Blue Sepharose CL-6B. The overall procedure resulted in a 1940-fold purification (specific activity 77.6mumol of nicotinamide released/h per mg). The purified enzyme displays a K(m) of 0.40mm for beta-NAD(+), a broad pH optimum around pH7.2 (0.1 m-potassium phosphate buffer) and an apparent M(r) of 120000. Nicotinamide is an inhibitor (K(i) 1.9mm) of the non-competitive type. The second reaction product ADP-ribose acts as a competitive inhibitor (K(i) 2.7mm). The purified enzyme splits beta-NAD(+), beta-NADP(+), beta-NADH and alpha-NAD(+) at rates in the relative proportions 1:0.75:<0.02:<0.02 and exhibits transglycosidase (pyridine-base exchange) activity. Anionic phospholipids such as phosphatidylinositol and phosphatidylserine inhibit the partially purified enzyme. A stimulating effect was observed upon the addition of histones.

Effect of 1-thiocarbamoyl-2-imidazolidinone on the generation of plaque forming cell responses

Although 1-thiocarbamoyl-2-imidazolidinone (TCI) is a highly potent modulator of cellular immunity, its effects on humoral immunity have not been investigated. Given orally to mice prior to immunization with sheep red blood cells (SRBC), low TCI doses (10(-14) to 10(-10) g/kg) suppressed primary plaque forming cell (PFC) responses of spleen cells by 50-75%. TCI effects in vivo were dependent on drug dose, antigen dose and time of drug administration relative to immunization. The kinetics of this response were not appreciably altered by TCI. Higher TCI doses, immunization with higher levels of SRBC than required to produce a maximal response or administration of TCI later than 48 hours after immunization resulted in drug effects ranging from slight suppression to mild enhancement of the primary PFC response. TCI given in vivo enhanced primary PFC responses to the T-independent antigen DNP-Ficoll by greater than 700%+. TCI given before a primary immunization suppressed a secondary PFC response to SRBC elicited 28 days later. However, when TCI was given 24 h prior to a secondary immunization, doses greater than 10(-5) g/kg were necessary to suppress the PFC response. The effect of TCI on in vitro immunized spleen cell cultures was similar to that found for in vivo immunized mice. TCI at concentrations up to 10(-1) g/l did not cause a loss of lymphocyte viability or inhibit plaque production by antibody producing cells. Effects of TCI on PFC responses in vitro were reversible if cells briefly exposed to an optimal concentration of drug were washed extensively prior to immunization.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological responsiveness of isolated rabbit tracheal epithelial cells

Surface tracheal epithelial cells (tracheocytes) from rabbit were isolated by treating intact tissue with chelators and proteolytic enzymes. The cells were viable as assessed by the following criteria: fluorescent viability staining, sequestration of lactate dehydrogenase, and maintenance of constant ATP levels. Radiolabeled Na+ was transported into cells with a rate constant of 0.06/min and an initial velocity of 1.6 nmol X 10(6) cells-1 X min-1 X beta-adrenergic agonists increased adenosine 3',5'-cyclic monophosphate (cAMP) levels in a time- and dose-dependent manner. The beta-adrenergic effects were potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine and blocked by propranolol. The tracheocytes retained the capacity to respond to beta-adrenergic agonists for at least 90 min after isolation. Two major cAMP binding proteins of apparent molecular weights of 50,000 and 54,000 were identified in tracheocytes with the photoaffinity label 8-N3-[32P]cAMP. Agents that increased cAMP levels in intact cells and unlabelled cAMP added to homogenates of cells that were not exposed to drugs decreased photoaffinity labeling. The two proteins correspond in electrophoretic mobility to the regulatory subunits of cAMP-dependent protein kinases I and II, respectively. The results demonstrate that the beta-adrenergic receptors and cAMP binding proteins identified in rabbit tracheal mucosa submucosa are present on tracheocytes, suggesting a role for these receptors in the regulation of tracheocyte physiological events.

Inhibition of T lymphocyte mitogenesis by 1,25-dihydroxyvitamin D3 (calcitriol)

Recent studies have suggested that vitamin D may have other important biologic activities in addition to its well-characterized role in the maintenance of calcium homeostasis. Discovery of cytosolic receptors for vitamin D in human peripheral blood monocytes and lectin-stimulated lymphocytes prompted us to study the effects of 1,25-dihydroxyvitamin D3 (calcitriol), the most biologically active metabolite of vitamin D, upon phytohemagglutinin (PHA)-induced lymphocyte blast transformation. We have found that calcitriol is a potent inhibitor of PHA-induced lymphocyte proliferation, achieving 70% inhibition of tritiated thymidine incorporation after 72 h in culture. Furthermore, calcitriol suppressed interleukin-2 (IL-2) production by PHA-stimulated peripheral blood mononuclear cells in a concentration-dependent fashion. Lastly, the suppressive effect of calcitriol on cellular proliferation was partially reversed by the addition of saturating amounts of purified IL-2. We conclude that calcitriol is a potent inhibitor of PHA-induced lymphocyte blast transformation and that this effect is mediated, in part, through suppression of IL-2 production. Thus, calcitriol appears to possess immunoregulatory properties that have been unappreciated heretofore.

Specificity of plasma cells in the rheumatoid synovium. I. Immunoglobulin class of antiglobulin-producing cells

Plasma cells synthesizing rheumatoid factors (RF) were identified by fluorescent staining of sections of synovium and macrophage-depleted cells from dispersed synovial tissue. The latter avoided problems related to sampling errors in studying tissue sections and in the uncertainty raised by the staining of macrophages with intracellular complexes. Plasma cells producing IgG predominated, and seropositive patients had a higher proportion of IgM producers than seronegative subjects. None the less, in both groups of patients more than 90% of the IgM plasma cells were synthesizing RF, whereas the corresponding figure for IgG was between 50% and 60%. Only around 10% of IgA plasma cells were positive for RF. The high percentage of IgM plasma cells making RF would tend to argue for an IgG-specific response and against direct polyclonal activation as the stimulus. The percentage of IgG-producing cells positive for RF is also consistent with a dominant response to IgG. Accepting the difference in the relative proportion of total IgM- to IgG-producing plasma cells in seropositive as against seronegative patients, the close similarity between the two groups in the fraction of cells making RF favours the view that the two groups have a comparable underlying immunopathology dependent on IgG autosensitization. From the technical standpoint, the dispersed cell method gives results in line with those obtained with sections but which are easier to read, whereas the fluorescent techniques described give clear and reproducible results for the detection of RF of different heavy-chain isotype.

Cimetidine suppression of CFU-C in males

A presumed cimetidine-induced granulocytopenia in a 6-year-old male with acute lymphocytic leukemia (ALL) prompted an investigation of the effects of cimetidine on in vitro bone marrow granulocyte colony growth (CFU-C) in normal individuals and ALL patients either on maintenance chemotherapy or off all therapy for at least 1 year. The addition of cimetidine resulted in a significant reduction of colony numbers as compared to untreated controls beginning at 1 x 10(-6) M (P less than 0.05) and increasing in significance as the concentration of cimetidine increased. Analysis of sex differences showed that CFU-C derived from females were not adversely affected by the addition of cimetidine (except at levels far in excess of recommended dosages) whereas CFU-C in males declined significantly from controls beginning at 1 x 10(-7) M (P less than 0.05) and became of greater significance as the concentration of cimetidine increased. These findings were identical for both normal individuals and ALL patients either receiving maintenance chemotherapy or off all therapy.

Effects of trifluoperazine, a calmodulin antagonist, on rabbit T- and B-cell responses to mitogens and antigen

Trifluoperazine (TFP), an inhibitor of the calcium-binding protein, calmodulin (CaM), was used to assess the role of calmodulin in the responses of rabbit lymphoid cells to stimulation with mitogen and antigen. After binding goat anti-rabbit Fab antibody, rabbit B cells lose their surface immunoglobulin (Ig) through endocytosis and then reexpress this protein during the next 24 hr. This reexpression was markedly inhibited by TFP. The brief and early addition of TFP markedly inhibited the increased [3H]thymidine (Tdr) uptake by rabbit T cells treated with concanavalin A and B cells exposed to anti-Fab. TFP greatly inhibited the induction by keyhole limpet hemocyanin (KLH) of the in vitro syntheses of antibody, Ig, and protein by KLH-primed lymph node cells (LNC). The earlier the TFP the greater was the inhibition of induction of these syntheses. However, once induced, synthesis and secretion of antibody were not inhibited by TFP. In striking contrast to the inhibition by TFP of the mitogenic and antigenic responses of lymphoid cells was the lack of effect of this drug on resting lymphocytes. Since TFP was not cytotoxic for either resting or mitogen- or antigen-stimulated LNC, it is highly unlikely that the observed inhibitory effects of this drug were due to its cytotoxicity. We postulate that an early signal for the activation of LNC proliferation, differentiation, and the syntheses of antibody, Ig, and protein involves a calcium-CaM-mediated reaction. Based on this work and that of others, the calcium-CaM complex may mediate an interaction between the ligand-occupied surface receptor and the cytoskeleton.

The thyroid "microsomal" antibody revisited. Its paradoxical binding in vivo to the apical surface of the follicular epithelium

We have shown that thyroid monolayers derived from the glands of patients with autoimmune thyroid disease have immunoglobulin (Ig) bound to their surface. This appears to have been deposited in vivo rather than during preparation of the monolayers, a view supported by our finding of such deposits on the apical margin of follicular cells in sections cut from these glands and stained with conjugated anti-immunoglobulin. It is likely that these deposits represent specific binding of so-called "microsomal" autoantibodies to the surface of the thyroid cells in vivo since staining of partially disrupted follicles ("half-melons") with Hashimoto serum containing microsomal autoantibodies in the indirect immunofluorescence (IFL) test, localized the antigen on the apical surface of the cells lining the follicular cavity. Thus, paradoxically, although the antigen is relatively inaccessible, autoantibodies do reach and combine with the thyroid surface in vivo and may therefore play a role in pathogenesis.

Variation in expression of mouse erythrocyte receptors on Epstein-Barr virus-induced B-cell lines

To explain the variation in the percentage of mouse erythrocyte rosette-forming cells (MERFC) during culture of Epstein-Barr virus (EBV)-induced B-cell lines, we provide evidence that (i) there is an altered expression of mouse red blood cell (MRBC) receptors on cell line cells during the mitotic cycle, and (ii) putative receptor-negative cells are capable of de novo synthesis of the receptor, and passively adsorbing receptor shed from receptor-positive cells.

Antilymphocyte autoantibody in lethal mouse malaria and its suppression by non-lethal malaria

Mice infected with lethal P. berghei or P. yoelii malaria develop anti-lymphocyte autoantibodies less than a week after infection. The autoantibodies are IgM, T-dependent and cytotoxic to a subpopulation of non-T lymphocytes at 37 degrees C in the presence of mouse or guinea-pig complement. Non-lethal P. yoelii and P. chabaudi do not induce these autoantibodies. X-irradiated P. berghei parasites induce autoantibodies in normal mice but not in mice infected with non-lethal P. yoelii suggesting an active suppressor mechanism in the non-lethal infection.

Anti-immunoglobulin-induced proliferative response of rabbit lymphocytes in a serum-free medium

The aim of this study was to determine if rabbit lymphocytes were activated with a specific ligand, anti-immunoglobulin (anti-Ig) in a well-defined serum-free medium. A modified medium, composed of Neuman-Tytell (NT) basal medium supplemented with BSA, transferrin (Tf), and fatty acids (FA), was found to support a vigorous anti-Ig-induced proliferative response of rabbit lymphocytes. The optimal concentrations of BSA, Tf and FA supplements were determined for the mitogen-induced response. The mitogenesis was enhanced by addition of 2-mercaptoethanol. The proliferation could be maintained for 10 days provided cells received fresh medium and mitogen on day 5. The presence of anti-Ig throughout the culture period is required for this extended proliferation. The response did not require the Fc portion of the anti-Ig and was blocked by soluble rabbit F(ab')2 fragments. The anti-Ig-activated blasts lacked a T cell surface marker and about half of them re-expressed sIg when anti-Ig was washed out (assayed 24 h later). The viability of the mitogen-induced cells on day 5 was above 55%, whereas the viability of the cells without mitogen was 36%. The supplemented NT medium could also support Con A-induced mitogenesis of rabbit lymphocytes. Additionally, Con A- and LPS-stimulated murine lymphocytes showed considerable proliferation for up to 5 days in the supplemented NT medium.

Suppression of in vitro lymphocyte DNA synthesis by killed Pseudomonas aeruginosa

Whole antibiotic-killed classic Pseudomonas aeruginosa organisms elicited human lymphocyte [3H]thymidine (TdR) uptake in vitro after 5 days in culture. However, high concentrations of the same preparation did not elicit [3H]TdR incorporation. The investigation of this lymphocyte unresponsiveness revealed that a high dose of P. aeruginosa, when added to lymphocyte cultures together with optimal concentrations of lymphocyte activators (e.g., plant lectins or whole killed Staphylococcus aureus Cowan 1), caused a potent, nonspecifically expressed inhibition of lymphocyte [3H]TdR uptake in response to these mitogens. High doses of P. aeruginosa were not cytotoxic to lymphocytes, and the inhibition caused was reversed when lymphocytes were washed free of bacteria. The inhibition of [3H]TdR uptake by high-dose P. aeruginosa did not require the generation of adherent suppressor cells or prostaglandin-mediated, steroid-sensitive or radiation-sensitive suppressor mechanisms. At optimal lymphocyte stimulatory concentrations of P. aeruginosa, the addition of indomethacin or the depletion of adherent cells caused an increase in lymphocyte [3H]TdR incorporation. This is consistent with an adherent-cell population regulating [3H]TdR uptake in response to P. aeruginosa via a prostaglandin-dependent pathway. This population was not involved in the inhibition of lymphocyte [3H]TdR uptake by high concentrations of P. aeruginosa.

Improved detection of drug cytotoxicity in the soft agar colony formation assay through use of a metabolizable tetrazolium salt

Use of a metabolizable tetrazolium salt was observed to facilitate assessments of tumor cell drug sensitivity in the soft-agar colony formation assay. Enzyme-mediated staining permits discrimination between viable and non-viable groups of cells so that drug-induced cytotoxicity is clearly identifiable by visual inspection as well as by computerized image analysis. The technique appears to be especially useful in the evaluation of primary tumor cell cultures which often contain substantial numbers of non-viable cellular aggregates.

The in vivo effect of a thymic factor (thymostimulin) on immunologic parameters of patients with untreated Hodgkin's disease

The in vivo effect of a calf thymus extract (thymostimulin, TS) on the E-rosetting capacity, PHA blastogenic response, serum migration inhibitory activity (LIF) and skin reactivity to recall antigens was evaluated in 19 untreated patients with Hodgkin's disease. In patients the mean percentage of peripheral blood lymphocytes forming E-rosettes increased from 47 to 55.7% (P less than or equal to 0.001; normal: 58.9). The mean PHA stimulation index rose with all three concentrations tested but did not reach normal values. Serum LIF was positive in only one patient prior to treatment with a mean LIF for all patients of 0.75 (P less than or equal to 0.005). Skin tests were positive in ten patients (52.6%) prior to therapy and 18 patients following therapy (94.7%; P less than or equal to 0.05). Thymostimulin, in vivo, appears to return immunologic competency to a population of untreated patients with Hodgkin's disease.