The role of the accessory cell in mitogen-stimulated human T cell gene expression

The role of the accessory cell in optimizing T cell proliferative responses to mitogens is a well known but poorly understood phenomenon. To further dissect the function of the accessory cell in allowing T cell proliferation, we compared mitogen-induced c-myc, interleukin 2 (IL 2), and IL 2 receptor gene expression in peripheral blood mononuclear cells (PBMC) and in T cells rigorously depleted of accessory cells through differential adherence and anti-Dr (anti-class II major histocompatibility antigen) monoclonal antibody complement-directed cytotoxicity. In cultures stimulated with phytohemagglutinin (PHA), a mitogen that requires accessory cells to induce T cell proliferation, expression of all measured genes was accessory cell dependent, since accumulation of their mRNA in PBMC was greater than that in cultures depleted of accessory cells. These genes varied in their accessory cell dependence, with IL 2 expression most dependent, c-myc expression least dependent, and IL 2 receptor expression intermediate in dependency. Use of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or ionomycin, mitogens that stimulate T cell proliferation independent of accessory cells, induced equal levels of gene expression in PBMC and in T cells depleted of accessory cells. These results suggest that PHA-stimulated T cells are dependent on an accessory cell signal(s) for optimal expression of the genes for c-myc, IL 2, and IL 2 receptor, and for proliferation. In addition, this signal(s) appears to be delivered early in the course of T cell activation events, since it can be bypassed by mitogens that directly activate protein kinase C (TPA) or induce calcium translocation (ionomycin). In addition, these data provide further evidence that expression of the c-myc protooncogene is insufficient for T cell mitogenesis, since PHA-induced accumulation of c-myc mRNA was only partially accessory cell dependent, whereas proliferation was completely accessory-cell dependent.

The role of the accessory cell in mitogen-stimulated human T cell gene expression

The role of the accessory cell in optimizing T cell proliferative responses to mitogens is a well known but poorly understood phenomenon. To further dissect the function of the accessory cell in allowing T cell proliferation, we compared mitogen-induced c-myc, interleukin 2 (IL 2), and IL 2 receptor gene expression in peripheral blood mononuclear cells (PBMC) and in T cells rigorously depleted of accessory cells through differential adherence and anti-Dr (anti-class II major histocompatibility antigen) monoclonal antibody complement-directed cytotoxicity. In cultures stimulated with phytohemagglutinin (PHA), a mitogen that requires accessory cells to induce T cell proliferation, expression of all measured genes was accessory cell dependent, since accumulation of their mRNA in PBMC was greater than that in cultures depleted of accessory cells. These genes varied in their accessory cell dependence, with IL 2 expression most dependent, c-myc expression least dependent, and IL 2 receptor expression intermediate in dependency. Use of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or ionomycin, mitogens that stimulate T cell proliferation independent of accessory cells, induced equal levels of gene expression in PBMC and in T cells depleted of accessory cells. These results suggest that PHA-stimulated T cells are dependent on an accessory cell signal(s) for optimal expression of the genes for c-myc, IL 2, and IL 2 receptor, and for proliferation. In addition, this signal(s) appears to be delivered early in the course of T cell activation events, since it can be bypassed by mitogens that directly activate protein kinase C (TPA) or induce calcium translocation (ionomycin). In addition, these data provide further evidence that expression of the c-myc protooncogene is insufficient for T cell mitogenesis, since PHA-induced accumulation of c-myc mRNA was only partially accessory cell dependent, whereas proliferation was completely accessory-cell dependent.

Effect of cyclosporin A and dexamethasone on interleukin 2 receptor gene expression

Here we demonstrate that CsA and DEX, at concentrations that markedly inhibited PHA-induced proliferation and IL 2 mRNA accumulation, partially diminished the expression of receptors for IL 2 on PBMC. This inhibition of IL 2 receptor expression occurred at a pretranslational level and involved a reduction in both high affinity and low affinity forms of the receptor. Although both CsA and DEX inhibited IL 2 receptor expression by about 50%, only CsA blocked the PHA-mediated induction of IL 2 responsivity in PBMC cultures. These data provide evidence that 1) CsA and DEX suppress the proliferation of T lymphocytes through distinct (though perhaps overlapping) mechanisms, 2) CsA (but not DEX) blocks the PHA-mediated induction of signals necessary for T cells to become capable of proliferating in response to IL 2, and 3) T cells regulate the expression of their genes for IL 2 and IL 2 receptors, at least in part, through independent mechanisms.

Effect of cyclosporin A and dexamethasone on interleukin 2 receptor gene expression

Here we demonstrate that CsA and DEX, at concentrations that markedly inhibited PHA-induced proliferation and IL 2 mRNA accumulation, partially diminished the expression of receptors for IL 2 on PBMC. This inhibition of IL 2 receptor expression occurred at a pretranslational level and involved a reduction in both high affinity and low affinity forms of the receptor. Although both CsA and DEX inhibited IL 2 receptor expression by about 50%, only CsA blocked the PHA-mediated induction of IL 2 responsivity in PBMC cultures. These data provide evidence that 1) CsA and DEX suppress the proliferation of T lymphocytes through distinct (though perhaps overlapping) mechanisms, 2) CsA (but not DEX) blocks the PHA-mediated induction of signals necessary for T cells to become capable of proliferating in response to IL 2, and 3) T cells regulate the expression of their genes for IL 2 and IL 2 receptors, at least in part, through independent mechanisms.

Sequential expression of protooncogenes during lectin-stimulated mitogenesis of normal human lymphocytes

The proliferation of non-neoplastic T lymphocytes is regulated, in part, by the coordinated expression of genes encoding T-cell growth factor (interleukin 2, IL2), IL2 receptors (IL2R), and transferrin receptors (TFR). In addition to growth factors and their receptors, protooncogenes may regulate lymphocyte proliferation. We used cloned cDNAs homologous to 21 different protooncogenes to screen for their expression at the mRNA level in human peripheral blood mononuclear cells (PBMC) stimulated with the mitogenic lectin phytohemagglutinin (PHA), and we compared the time course of accumulation of mRNAs for these protooncogenes to that of mRNAs for the IL2, IL2R, TFR, and histone H3 genes. mRNAs for c-abl, c-ets, c-yes, and N-ras were present in unstimulated PBMC. After stimulation of PBMC by PHA, we detected marked increases within 10 min in the levels of mRNA for c-fos and c-myc; within 6 hr for IL2 and IL2R mRNAs; within 14 hr for c-myb, p53, N-ras, and TFR mRNAs; and within 24-36 hr for H3 mRNA. Expression of c-abl, c-ets, and c-yes increased gradually following stimulation with PHA. None of the other protooncogenes tested was expressed in PBMC. Addition of the protein synthesis inhibitor cycloheximide, before the addition of PHA to cultures, abolished the PHA-induced accumulation of mRNAs for c-myb, N-ras, and TFR, but not of mRNAs for c-fos, c-myc, IL2, and IL2R. These data indicate that c-fos, c-myc, IL2, and IL2R belong to a group of genes expressed early, whereas c-myb, N-ras, and TFR belong to a group of genes expressed later in PHA-activated PBMC, and that the products of the c-fos and c-myc protooncogenes are not required for expression of IL2 or IL2R genes. Addition of purified IL2 augmented the expression of the later-expressed genes c-myb, p53, N-ras, and TFR in PHA-stimulated cultures of PBMC, as well as of the early genes c-myc and IL2R, but not of c-fos and IL2, thus suggesting that PHA and IL2 stimulate the expression of overlapping, but nonidentical, sets of genes in PBMC.

Characterization of left ventricular chamber distortion: alterations in cavity shape and orientation in mitral stenosis

Distortion of the left ventricular (LV) chamber silhouette was identified in 28 patients with mitral stenosis (MS) by disparity between normally identical chamber volumes calculated independently from the frontal (AP) and lateral (LAT) views of biplane cineangiograms (AP end diastolic volume 157.8 +/- 10.0 ml, LAT end diastolic volume 115.6 +/- 7.2 ml, p less than .001). Similar systematic disparity was observed in estimates of end systolic volume in these views. While no directional difference in ejection fraction was found, identical (+/- 10%) AP and LAT measurements were obtained in only 36% of patients, indicating poor reproducibility of the estimate of LV function between single radiographic views. A technique was also devised for determining the spatial orientation of the LV long axis (mid mitral valve to apex) from biplane cineangiograms; this axis was shown to intercept the frontal plane at an angle of 50.9 +/- 2.4 degrees in 12 subjects with normal LV anatomy and 36.1 +/- 4.5 degrees in seven patients with MS, indicating that the long axis was rotated posteriorly toward alignment with the frontal plane in the latter group. The presence and magnitude of LV chamber distortion was clearly related to the degree of angiographically estimated right ventricular dilatation. Implications of these observations, particularly with reference to the estimation of single plane LV volume characteristics in patients with MS, are discussed.

Preliminary studies of diabetic decompensation assessed with bedside glucose-monitoring techniques

Blood glucose-monitoring techniques originally developed to aid outpatient management of diabetic patients are now being used to facilitate hospital care. However, applications in hyperglycemic patients have been limited because many glucose-oxidase strips and meters respond only to glucose values less than or equal to 400 mg/dl. We asked if prior dilution of blood samples would permit reliable estimations. Ten consecutive decompensated diabetic patients (age 35-73, glucose 506-879, HCO3 12-28) had blood glucose determinations done simultaneously by the hospital laboratory and by Chemstrip bG after dilution of heparinized blood 1:2 in saline. Thirty-one samples were obtained before and during insulin therapy. Correlations with laboratory glucose values were 0.95 with strips read by Accu-Chek meter and 0.90 read visually, both P less than 0.001. Average deviations from laboratory values were 7.9% with Accu-Chek and 12.9% with visual readings. Accu-Chek deviations averaged 9.6% for glucose greater than 700 mg/dl, and 6.9% for glucose greater than 400 mg/dl. Over the first hour of insulin therapy, glucose fell 150 +/- 30 mg/dl by Accu-Chek, comparable to 168 +/- 29 by laboratory measurement; the decrement by visual reading was 107 +/- 32, not significantly different. We conclude that dilution of blood samples with glucose greater than 400 allows reliable estimation of elevated values by home glucose-monitoring techniques. This approach is cost-effective and provides the rapid feedback needed for the management of critically ill patients.

Recombinant interleukin 2 regulates levels of c-myc mRNA in a cloned murine T lymphocyte

The cellular oncogene c-myc has been implicated in the regulation of growth of normal and neoplastic cells. Recently, it was suggested that c-myc gene expression may control the G0----G1-phase transition in normal lymphocytes that were stimulated to enter the cell cycle by the lectin concanavalin A (ConA). Here we describe the effects of purified recombinant interleukin 2 (rIL2) and of ConA on levels of c-myc mRNA in the noncytolytic murine T-cell clone L2. In contrast to resting (G0) primary cultures of lymphocytes, quiescent L2 cells have a higher RNA content than resting splenocytes and express receptors for interleukin 2 (IL2). Resting L2 cells are therefore best regarded as early G1-phase cells. Purified rIL2 was found to stimulate the rapid accumulation of c-myc mRNA in L2 cells. Levels of c-myc mRNA became maximal within 1 h and declined gradually thereafter. In contrast, ConA induced slower accumulation of c-myc mRNA in L2 cells, with increased levels of c-myc mRNA becoming detectable 4 to 8 h after stimulation. Experiments with the protein synthesis inhibitor cycloheximide demonstrated that the increase in levels of c-myc mRNA that were induced by ConA was a direct effect of this lectin and not secondary to IL2 production. Cyclosporin A, an immunosuppressive agent, markedly reduced the accumulation of c-myc mRNA that was induced by ConA but only slightly diminished the accumulation of c-myc mRNA that was induced by rIL2. Taken together, these data provide evidence that (i) c-myc gene expression can be regulated by at least two distinct pathways in T lymphocytes, only one of which is sensitive to cyclosporine A, and (ii) the accumulation of c-myc mRNA can be induced in T cells by IL2 during the G1 phase of the cell cycle.

Monoclonal antibody OKT11A inhibits and recombinant interleukin 2 (IL 2) augments expression of IL 2 receptors at a pretranslational level

The expression of receptors for interleukin 2 (IL 2) represents a critical event regulating the growth of normal T lymphocytes. We investigated the effects of the inhibitory monoclonal antibody OKT11A (anti-sheep erythrocyte receptor) and of purified recombinant IL 2 (rIL 2) on the expression of IL 2 receptors by activated T cells at both the protein and the mRNA levels. Adding OKT11A antibody (0.5 microgram/ml) to phytohemagglutinin (PHA)-stimulated cultures of human peripheral blood mononuclear cells (PBMC) markedly suppressed cellular proliferation (assessed by [3H]thymidine incorporation) and IL 2 receptor expression (determined by immunofluorescence assay by using the anti-IL 2-receptor antibody, anti-Tac). Northern blot analysis performed with the use of a cDNA probe specific for the human IL 2 receptor gene demonstrated that OKT11A antibody also decreased the accumulation of IL 2 receptor mRNA induced by PHA in PBMC. Purified rIL 2 (10 U/ml) alone had little effect on the expression of IL 2 receptors in unstimulated PBMC cultures. In combination with PHA or with PHA plus OKT11A, however, rIL 2 augmented both the expression of IL 2 receptor protein on PBMC and the accumulation of IL 2 receptor mRNA in PBMC. Adding anti-Tac antibody to PBMC cultures to block the interaction of IL 2 with its receptor diminished the accumulation of IL 2 receptor mRNA induced by PHA. Taken together, these data demonstrate that OKT11A antibody inhibits and IL 2 augments expression of IL 2 receptors on PHA-stimulated T cells, at least in part, at a pretranslational level.

Monoclonal antibody OKT11A inhibits and recombinant interleukin 2 (IL 2) augments expression of IL 2 receptors at a pretranslational level

The expression of receptors for interleukin 2 (IL 2) represents a critical event regulating the growth of normal T lymphocytes. We investigated the effects of the inhibitory monoclonal antibody OKT11A (anti-sheep erythrocyte receptor) and of purified recombinant IL 2 (rIL 2) on the expression of IL 2 receptors by activated T cells at both the protein and the mRNA levels. Adding OKT11A antibody (0.5 microgram/ml) to phytohemagglutinin (PHA)-stimulated cultures of human peripheral blood mononuclear cells (PBMC) markedly suppressed cellular proliferation (assessed by [3H]thymidine incorporation) and IL 2 receptor expression (determined by immunofluorescence assay by using the anti-IL 2-receptor antibody, anti-Tac). Northern blot analysis performed with the use of a cDNA probe specific for the human IL 2 receptor gene demonstrated that OKT11A antibody also decreased the accumulation of IL 2 receptor mRNA induced by PHA in PBMC. Purified rIL 2 (10 U/ml) alone had little effect on the expression of IL 2 receptors in unstimulated PBMC cultures. In combination with PHA or with PHA plus OKT11A, however, rIL 2 augmented both the expression of IL 2 receptor protein on PBMC and the accumulation of IL 2 receptor mRNA in PBMC. Adding anti-Tac antibody to PBMC cultures to block the interaction of IL 2 with its receptor diminished the accumulation of IL 2 receptor mRNA induced by PHA. Taken together, these data demonstrate that OKT11A antibody inhibits and IL 2 augments expression of IL 2 receptors on PHA-stimulated T cells, at least in part, at a pretranslational level.

Stimulation and inhibition of human T cell subsets by wheat germ agglutinin

Wheat germ agglutinin (WGA), a tetravalent lectin, has both stimulatory and inhibitory effects on human T lymphocytes. It has been suggested that these actions are related and that WGA selectively stimulates a suppressive subset of T cells. We studied the ability of WGA to stimulate and inhibit subpopulations of human peripheral blood mononuclear cells (PBMC) known to have helper or suppressor activity. Fresh human PBMC were depleted of either T4+ or T8+ cells by using antibody-mediated complement lysis. The resultant cell populations were stimulated with WGA, and the proliferative response was assessed by [3H]thymidine incorporation, IL 2 receptor expression, the ability to elaborate IL 2 in culture supernatants, and the susceptibility to inhibition by the monoclonal antibody anti-Tac. Similar experiments with cells from a WGA-responsive continuous T cell culture were also performed. WGA inhibited phytohemagglutinin (PHA)-induced proliferation of PBMC depleted of either T4+ or T8+ cells. WGA also inhibited PBMC that had been depleted of adherent cells and Ia+ cells and then induced to proliferate with a combination of TPA and PHA. Our findings indicate that WGA induces IL 2-dependent proliferation in a small proportion of both T4+ and T8+ lymphocytes. We also provide evidence that the inhibitory activity of WGA is not mediated by a T4+, T8+, or Ia+ cell, suggesting that WGA acts directly on the proliferating cell rather than selectively stimulating a suppressive subpopulation.

Stimulation and inhibition of human T cell subsets by wheat germ agglutinin

Wheat germ agglutinin (WGA), a tetravalent lectin, has both stimulatory and inhibitory effects on human T lymphocytes. It has been suggested that these actions are related and that WGA selectively stimulates a suppressive subset of T cells. We studied the ability of WGA to stimulate and inhibit subpopulations of human peripheral blood mononuclear cells (PBMC) known to have helper or suppressor activity. Fresh human PBMC were depleted of either T4+ or T8+ cells by using antibody-mediated complement lysis. The resultant cell populations were stimulated with WGA, and the proliferative response was assessed by [3H]thymidine incorporation, IL 2 receptor expression, the ability to elaborate IL 2 in culture supernatants, and the susceptibility to inhibition by the monoclonal antibody anti-Tac. Similar experiments with cells from a WGA-responsive continuous T cell culture were also performed. WGA inhibited phytohemagglutinin (PHA)-induced proliferation of PBMC depleted of either T4+ or T8+ cells. WGA also inhibited PBMC that had been depleted of adherent cells and Ia+ cells and then induced to proliferate with a combination of TPA and PHA. Our findings indicate that WGA induces IL 2-dependent proliferation in a small proportion of both T4+ and T8+ lymphocytes. We also provide evidence that the inhibitory activity of WGA is not mediated by a T4+, T8+, or Ia+ cell, suggesting that WGA acts directly on the proliferating cell rather than selectively stimulating a suppressive subpopulation.

Regulation of c-myc mRNA levels in normal human lymphocytes by modulators of cell proliferation

Increased expression of the cellular oncogene c-myc has recently been demonstrated in some types of proliferating non-neoplastic cells, including lectin mitogen-stimulated lymphocytes, suggesting a role for this protooncogene in the regulation of growth of normal cells. Here we report the effects of several modulators of lymphocyte proliferation on the steady-state levels of c-myc mRNA in human peripheral blood mononuclear cells (PBMC). Stimulating PBMC with lectin mitogen phytohemagglutinin (PHA), phorbol ester phorbol 12-myristate 13-acetate, calcium ionophore ionomycin, or monoclonal antibody OKT3 (anti-antigen receptor complex) produced marked increases in c-myc mRNA levels within 3 hr. Recombinant interleukin 2 (rIL-2; Cetus) had little effect on c-myc expression but, in combination with PHA, it augmented levels of c-myc transcripts measured at 24 hr but not at 3 hr. Adding various inhibitors of lymphocyte proliferation to PHA-stimulated cultures revealed that cyclosporin A, dexamethasone, and OKT11A antibody (anti-sheep erythrocyte receptor) diminished levels of c-myc mRNA measured at 3 hr and 24 hr, whereas anti-Tac (anti-IL-2-receptor) inhibited at 24 hr but not at 3 hr. Thus, cyclosporin A, dexamethasone, and OKT11A interfere with early events of T-cell activation, whereas anti-Tac acts later. Hydroxyurea and 42/6 antibody (anti-transferrin receptor), which impair the G1----S transition in cycling cells, failed to inhibit c-myc expression and instead delayed the decrease in c-myc mRNA levels that normally occurs with the onset of DNA synthesis. These data indicate that c-myc is regulated (in normal lymphocytes) at several points in the cell cycle.

Functional properties of the 50 kd protein associated with the E-receptor on human T lymphocytes: suppression of IL 2 production by anti-p50 monoclonal antibodies

Monoclonal antibody 9.6 is specific for a 50 kd T cell surface protein (p50) associated with the sheep erythrocyte (E)-receptor on human T lymphocytes. This antibody interferes with many T cell functions. We have examined the effect of antibody 9.6 on lymphocyte proliferation and interleukin 2 (IL 2) production triggered by mitogens, soluble antigens, and alloantigens to elucidate the mechanism(s) of its immunosuppressive action. At concentrations as low as 50 ng/ml, 9.6 suppressed lymphocyte proliferation and the elaboration of IL 2 by T cells stimulated by PHA, alloantigens, or low concentrations of the phorbol ester TPA (less than or equal to ng/ml). Furthermore, in cultures stimulated by a combination of PHA plus TPA, 9.6 did not inhibit the acquisition of IL 2 receptors but inhibited proliferation and IL 2 production. Immunoaffinity-purified IL 2 completely restored lymphocyte proliferation in cultures inhibited by 9.6. Studies of kinetics of inhibition by 9.6 showed that this antibody inhibited lymphocyte proliferation induced by PHA, alloantigen, and PPD even when added at 24, 48, and 72 hr, respectively, after the initiation of these cultures, suggesting that 9.6 does not block lectin binding or antigen recognition by T cells and that it can inhibit lymphocyte proliferation even after cells have undergone one or more rounds of cell division. A dose-response analysis of lymphocyte proliferation induced by PHA or by TPA demonstrated that the degree of inhibition by 9.6 decreased with increasing concentrations of these mitogens. Antibody 9.6 did not inhibit lymphocyte response induced by optimal concentrations of PHA (50 to 100 micrograms/ml; PHA-M) but inhibited proliferation of maximally induced lymphocytes by using a synergistic combination of low concentrations of PHA (5 micrograms/ml, PHA-M) plus TPA (1 ng/ml). Taken together, these findings indicate that 1) 9.6 inhibits lymphocyte proliferation by affecting IL 2 production, 2) 9.6 does not inhibit the acquisition of 9.6 receptors induced by a synergistic combination of PHA plus TPA, and 3) p50 molecules may be involved in multiple pathways of T cell activation.

Functional properties of the 50 kd protein associated with the E-receptor on human T lymphocytes: suppression of IL 2 production by anti-p50 monoclonal antibodies

Monoclonal antibody 9.6 is specific for a 50 kd T cell surface protein (p50) associated with the sheep erythrocyte (E)-receptor on human T lymphocytes. This antibody interferes with many T cell functions. We have examined the effect of antibody 9.6 on lymphocyte proliferation and interleukin 2 (IL 2) production triggered by mitogens, soluble antigens, and alloantigens to elucidate the mechanism(s) of its immunosuppressive action. At concentrations as low as 50 ng/ml, 9.6 suppressed lymphocyte proliferation and the elaboration of IL 2 by T cells stimulated by PHA, alloantigens, or low concentrations of the phorbol ester TPA (less than or equal to ng/ml). Furthermore, in cultures stimulated by a combination of PHA plus TPA, 9.6 did not inhibit the acquisition of IL 2 receptors but inhibited proliferation and IL 2 production. Immunoaffinity-purified IL 2 completely restored lymphocyte proliferation in cultures inhibited by 9.6. Studies of kinetics of inhibition by 9.6 showed that this antibody inhibited lymphocyte proliferation induced by PHA, alloantigen, and PPD even when added at 24, 48, and 72 hr, respectively, after the initiation of these cultures, suggesting that 9.6 does not block lectin binding or antigen recognition by T cells and that it can inhibit lymphocyte proliferation even after cells have undergone one or more rounds of cell division. A dose-response analysis of lymphocyte proliferation induced by PHA or by TPA demonstrated that the degree of inhibition by 9.6 decreased with increasing concentrations of these mitogens. Antibody 9.6 did not inhibit lymphocyte response induced by optimal concentrations of PHA (50 to 100 micrograms/ml; PHA-M) but inhibited proliferation of maximally induced lymphocytes by using a synergistic combination of low concentrations of PHA (5 micrograms/ml, PHA-M) plus TPA (1 ng/ml). Taken together, these findings indicate that 1) 9.6 inhibits lymphocyte proliferation by affecting IL 2 production, 2) 9.6 does not inhibit the acquisition of 9.6 receptors induced by a synergistic combination of PHA plus TPA, and 3) p50 molecules may be involved in multiple pathways of T cell activation.

Suppression of interleukin 2 receptor acquisition by monoclonal antibodies recognizing the 50 KD protein associated with the sheep erythrocyte receptor on human T lymphocytes

Monoclonal antibodies OKT11A, 9.6, and 35.1 recognize epitopes on a 50000 dalton surface molecule (p50) identical to or closely associated with the sheep erythrocyte receptor (E receptor) on human T lymphocytes. These three antibodies were investigated for ability to inhibit T cell proliferation and interleukin 2 (IL 2) receptor acquisition (determined with anti-Tac antibody in an immunofluorescence assay) induced by the lectin mitogen phytohemagglutinin (PHA) or by the phorbol ester 12-O-tetradecanoyl-phorbol-13 acetate (TPA). OKT11A, 9.6, and 35.1 were found to suppress [3H]thymidine incorporation and IL 2 receptor acquisition stimulated by PHA but not by TPA. This inhibition was not attributable to a lag in kinetics, but was sustained throughout 4 to 5 days of culture. Because OKT11A and 9.6 have been reported to suppress lectin mitogen-induced IL 2 production, we attempted to overcome inhibition of proliferation with exogenous IL 2 (MLA144 supernatants or immunoaffinity-purified human IL 2). Adding IL 2 at the initiation of culture abrogated the suppressive effect of all three anti-p50 antibodies on proliferation and on the acquisition of IL 2 receptors, raising the possibility that IL 2 may up-regulate expression of its cellular receptor on human T lymphocytes. These data, together with previous reports, indicate that OKT11A, 9.6, and 35.1 suppress lectin mitogen-induced T cell proliferation by impairing both IL 2 elaboration and IL 2 receptor acquisition, and suggest that IL 2 may be capable, at least under some conditions, of increasing expression of IL 2 receptors on human T lymphocytes.

Suppression of interleukin 2 receptor acquisition by monoclonal antibodies recognizing the 50 KD protein associated with the sheep erythrocyte receptor on human T lymphocytes

Monoclonal antibodies OKT11A, 9.6, and 35.1 recognize epitopes on a 50000 dalton surface molecule (p50) identical to or closely associated with the sheep erythrocyte receptor (E receptor) on human T lymphocytes. These three antibodies were investigated for ability to inhibit T cell proliferation and interleukin 2 (IL 2) receptor acquisition (determined with anti-Tac antibody in an immunofluorescence assay) induced by the lectin mitogen phytohemagglutinin (PHA) or by the phorbol ester 12-O-tetradecanoyl-phorbol-13 acetate (TPA). OKT11A, 9.6, and 35.1 were found to suppress [3H]thymidine incorporation and IL 2 receptor acquisition stimulated by PHA but not by TPA. This inhibition was not attributable to a lag in kinetics, but was sustained throughout 4 to 5 days of culture. Because OKT11A and 9.6 have been reported to suppress lectin mitogen-induced IL 2 production, we attempted to overcome inhibition of proliferation with exogenous IL 2 (MLA144 supernatants or immunoaffinity-purified human IL 2). Adding IL 2 at the initiation of culture abrogated the suppressive effect of all three anti-p50 antibodies on proliferation and on the acquisition of IL 2 receptors, raising the possibility that IL 2 may up-regulate expression of its cellular receptor on human T lymphocytes. These data, together with previous reports, indicate that OKT11A, 9.6, and 35.1 suppress lectin mitogen-induced T cell proliferation by impairing both IL 2 elaboration and IL 2 receptor acquisition, and suggest that IL 2 may be capable, at least under some conditions, of increasing expression of IL 2 receptors on human T lymphocytes.

Effect of wheat germ agglutinin on the interleukin pathway of human T lymphocyte activation

Wheat germ agglutinin (WGA) inhibits proliferation of human peripheral blood mononuclear cells (PBMC) induced by mitogens and antigens. We investigated the mechanism by which WGA inhibits PHA-induced human lymphocyte proliferation with regard to the interleukin pathway. Our data revealed that although PBMC-proliferation was markedly suppressed by WGA, levels of IL 2 activity in WGA-inhibited cultures were not reduced, but instead were increased, suggesting failure to utilize IL 2. Furthermore, the addition of exogenous IL 2 failed to overcome the suppression. Consistent with these observations, culturing PBMC with PHA plus WGA markedly decreased the number of high-affinity IL 2 receptor per cell, as determined by binding of purified [3H]IL 2, relative to cultures containing PHA alone. WGA immobilized on support beads bound detergent-solubilized IL 2 receptors from PHA-activated T cells, but did not bind human IL 2. However, WGA did not competitively block the binding of [3H]IL 2 to PHA-induced lymphoblasts. These results suggest that WGA inhibits lymphocyte proliferation by binding to and decreasing the number of high-affinity IL 2 receptors displayed on T cells, without impairing IL 2 production.

Effect of wheat germ agglutinin on the interleukin pathway of human T lymphocyte activation

Wheat germ agglutinin (WGA) inhibits proliferation of human peripheral blood mononuclear cells (PBMC) induced by mitogens and antigens. We investigated the mechanism by which WGA inhibits PHA-induced human lymphocyte proliferation with regard to the interleukin pathway. Our data revealed that although PBMC-proliferation was markedly suppressed by WGA, levels of IL 2 activity in WGA-inhibited cultures were not reduced, but instead were increased, suggesting failure to utilize IL 2. Furthermore, the addition of exogenous IL 2 failed to overcome the suppression. Consistent with these observations, culturing PBMC with PHA plus WGA markedly decreased the number of high-affinity IL 2 receptor per cell, as determined by binding of purified [3H]IL 2, relative to cultures containing PHA alone. WGA immobilized on support beads bound detergent-solubilized IL 2 receptors from PHA-activated T cells, but did not bind human IL 2. However, WGA did not competitively block the binding of [3H]IL 2 to PHA-induced lymphoblasts. These results suggest that WGA inhibits lymphocyte proliferation by binding to and decreasing the number of high-affinity IL 2 receptors displayed on T cells, without impairing IL 2 production.

Unusual radiologic manifestations of bronchogenic cyst

We have presented four cases of bronchogenic cyst, emphasizing the uncommon radiologic manifestations, including air trapping and/or lobulated contour. Two of the cysts were in the lung parenchyma, one in the left hilum adherent to the left lower lobe bronchus, and one in the posterior mediastinum. Recognition of the unusual radiologic features aids in establishing an appropriate differential diagnosis and directing subsequent evaluation.

Metastatic melanoma in the thorax: report of 130 patients

Early detection of metastatic melanoma has become more important as newer and more effective therapeutic regimens are used. Between 1970 and 1980, 1,600 patients were treated at one institution for malignant melanoma. Of these, 260 (16.3%) developed thoracic metastasis. Satisfactory chest radiographs were available for analysis in 130 of 260 patients. The patterns of the intrathoracic metastasis include multiple pulmonary nodules (52 patients), solitary nodule (26), miliary pattern (two), mediastinal and/or hilar adenopathy (nine), pleural effusion (three), lytic bony lesions (one), extra-pleural mass (one), and combined lesions (36). Both the staging of melanoma and the radiographic pattern of thoracic metastasis seemed to prognosticate the survival rate of these patients. Miliary metastasis and bone destruction implied a grave prognosis. Patients with a solitary lung nodule had the best survival experience. Immunotherapy, chemotherapy, and surgery of selected distal metastases significantly improved the survival of most of these patients.

Nevus leiomyomatosus systematicus

Leiomyomas of the skin are classified as pilar, genital, or angioleiomyoma depending on the site of origin. Pilar leiomyomas are the most common form, and usually multiple tumors are found in a single patient. An unusual variant of multiple pilar leiomyoma is nevus leiomyomatosus systematicus, a descriptive term used when tumors are wide-spread and patterned, suggesting a nevoid condition. Many of the large pilar tumors are painful and require surgical excision for relief of symptoms.

Blockade of frontocortical-brain stem pathway prevents ventricular fibrillation of ischemic heart

The hypothesis tested was that functional blockade of a pathway known to travel from the frontal cortex through the posterior hypothalamus to the brain stem might prevent the occurrence of ventricular fibrillation (VF) in the ischemic heart of conscious stressed pigs. The hypothesis was based on previous findings that 1) psychological stress is a necessary factor for the initiation of VF in the ischemic heart of conscious pigs, 2) the frontal cortex and its related thalamic gating mechanism, uniquely show neuroelectric responses to stressful stimuli, and 3) direct electric stimulation of either the frontal cortex, posterior hypothalamus, or fields of Forel will produce ventricular arrhythmias and myocardial necrosis. In the present study it was found that cryogenic blockade of the forebrain, posterior hypothalamus, or fields of Forel prevents or delays VF after left anterior descending coronary artery occlusion in conscious stressed pigs (P less than 0.01). Blockade of control structures adjacent to these loci in another group of pigs had no effect on VF latency. Neither heart rate nor electroencephalographic changes could explain the differences between the groups. The results show that blockade of the frontocortical-brain stem pathway prevents the lethal consequences of myocardial ischemia in stressed animals.