Cervical cancer cells induce apoptosis of cytotoxic T lymphocytes

The goal of immunotherapy is to eliminate tumors by generating tumor-specific cytotoxic T lymphocytes (CTLs) in patients or by adoptively transferring ex vivo-activated CTLs into patients. Clinical trials have shown that tumor-specific CTLs often disappear before tumors are completely eliminated. In this study, the authors show that CTLs specific for cervical tumor cells undergo apoptosis after they are co-cultured with cervical tumor cells. The established cervical tumor cell lines and cervical cancer tissues express CD95 (Fas/Apo-1) ligand. The tumor cell-induced T-cell apoptosis can be blocked by an inhibitory anti-CD95 (APO-1/Fas) antibody, indicating that tumor cells induce apoptosis of CTLs through CD95-CD95 ligand interaction. Addition of interleukin-2 (IL-2) and IL-7 into the culture rescues the CTL from tumor cell-induced apoptosis. The rescued T cells retain their full antitumor cytotoxicity. These data suggest that human cervical tumor cells might actively down-regulate a cellular immune response by inducing apoptosis of specific T cells during immunotherapy. Local use of IL-2 and IL-7 as adjuvants may promote survival of the CTL and, thus, enhance the efficacy of immunotherapy.

[Clinic and immunophenotypic studies on midline malignant histiocytosis]

OBJECTIVE

To understand the clinic opatholgic changes of midline malignant histiocytosis (MMH), and to explain the source of atypical lymphoid cells (ALC) of MMH, so as to search after the relation between MMH and malignant lymphoma.

METHOD

Histopathologic section of 39 cases of MMH were taken HE staining and the histopathologic changes were obsered under microscope. The immunohistochemical staining was also used to examine the immunophenotype of ALC.

RESULT

1. Pathologic changes of MMH: coaglation necrosis and mixed inflammatory cells infiltration, with epithelial infiltration which distributed around the center of blood vessel were their characteristics. 2. Immunohistochemical staining result: 28 in 39 cases of MMH (71.8%) expressed the immunophenvtype of T-cell; among them 13 (33.3%) were finded both positive reaction to CD3 and CD57 antigens with ALCs at the same time.

CONCLUSION

According to immunophenotypic studies, most ALCs came from proliferation and infiltration of atypical T cell. ALCs of MMH expressed not only T-cell markers (CD3), but also NK-associated antigen (CD57). MMH was a mucosa related peripheral T/NK cell lymphoma originally.

Novel TRH analog improves motor and cognitive recovery after traumatic brain injury in rodents

Thyrotropin-releasing hormone (TRH) and certain TRH analogs show substantial neuroprotective effects in experimental brain or spinal cord trauma but also have other physiological actions (autonomic, analeptic, and endocrine) that may be undesirable for the treatment of neurotrauma in humans. We developed a novel TRH analog (2-ARA-53a), with substitutions at the NH(2)-terminus and imidazole ring, that preserves the neuroprotective action of TRH-like compounds while decreasing or eliminating their autonomic, analeptic, and endocrine effects. Rats administered 2-ARA-53a (1.0 mg/kg, n = 17) intravenously 30 min after lateral fluid percussion brain injury showed marked improvement in motor recovery compared with vehicle-treated controls (n = 14). Treatment of mice subjected to moderate controlled cortical impact brain injury, at the same dose and time after trauma (n = 8), improved both motor recovery and cognitive performance in a water maze place learning task compared with vehicle-treated controls (n = 8). In injured rats, no autonomic or analeptic effects were observed with this compound, and endocrine effects were significantly reduced with 2-ARA-53a, in contrast to those found with a typical NH(2)-terminal-substituted TRH analog (YM-14673). These findings demonstrate that the neuroprotective effects of TRH-related compounds can be dissociated from their other major physiological actions and suggest a potential role for dual-substituted TRH analogs in the treatment of clinical neurotrauma.

Probing the binding of indolactam-V to protein kinase C through site-directed mutagenesis and computational docking simulations

Protein kinase C (PKC) comprises a family of ubiquitous enzymes transducing signals by the lipophilic second messenger sn-1, 2-diacylglycerol (DAG). Teleocidin and its structurally simpler congener indolactam-V (ILV) bind to PKC with high affinity. In this paper, we report our computational docking studies on ILV binding to PKC using an automatic docking computer program, MCDOCK. In addition, we used site-directed mutagenesis to assess the quantitative contribution of crucial residues around the binding site of PKC to the binding affinity of ILV to PKC. On the basis of the docking studies, ILV binds to PKC in its cis-twist conformation and forms a number of optimal hydrogen bond interactions. In addition, the hydrophobic groups in ILV form "specific" hydrophobic interactions with side chains of a number of conserved hydrophobic residues in PKC. The predicted binding mode for ILV is entirely consistent with known structure-activity relationships and with our mutational analysis. Our mutational analysis establishes the quantitative contributions of a number of conserved residues to the binding of PKC to ILV. Taken together, our computational docking simulations and analysis by site-directed mutagenesis provide a clear understanding of the interaction between ILV and PKC and the structural basis for design of novel, high-affinity, and isozyme-selective PKC ligands.

Human papillomavirus type 16 E7 DNA vaccine: mutation in the open reading frame of E7 enhances specific cytotoxic T-lymphocyte induction and antitumor activity

A human papillomavirus type 16 E7 DNA vaccine with the open reading frame encoding mutations in two zinc-binding motifs expressed a rapidly degraded E7 protein. This vaccine induced a significantly stronger E7-specific cytotoxic T-lymphocyte response and better tumor protection in mice than did a wild-type E7 DNA vaccine expressing a stable E7 protein.

The effects of cell density, attachment substratum and dexamethasone on spontaneous apoptosis of rat hepatocytes in primary culture

The rates of spontaneous cell detachment, cell viability, and apoptosis in primary cultures of rat hepatocytes plated at high and low density were compared. Apoptosis was frequent in detached cells, and the rates of cell detachment and apoptosis were greater in high-density than in low-density cultures. Among attached cells, more cells had condensed or fragmented nuclei in high-density than in low-density cultures. Further, ladder-like DNA fragmentation was not seen in low-cell-density cultures but was clearly evident in high-density cultures. Bax was more highly expressed in cells cultured at high density, and on collagen vs. matrigel, whereas changes of Bcl-2 and Fas expression observed in culture appeared unrelated to the rate of apoptosis. The rate of hepatocyte apoptosis appeared to be identical in low-density cultures on collagen 1 and matrigel, but when cells were cultured at high density, matrigel suppressed apoptosis by more than 50% at 36 h. In hepatocytes cultured on collagen 1, dexamethasone (0.1 microM) suppressed apoptosis in both low- and high-density cultures; higher doses had no further effects. In high density cultures, aurintricarboxylic acid (10 microM) suppressed apoptosis and this improved cell attachment at 48 h. It is concluded that cell viability in primary cultures of rat hepatocytes grown on collagen I is dependent on optimal culture density and that the cell population is regulated, at least in part, by apoptosis. Corticosteroids suppress spontaneous apoptosis of cultured hepatocytes in a non-dose-dependent manner, whereas matrigel abolishes apoptosis induced by increasing cell density. Bax may be an important protein in the cell density and cell matrix-dependent regulation of apoptosis in cultured hepatocytes.

[Determination of cortisol in plasma and 24-hour urine of patients with central serous chorioretinopathy]

OBJECTIVE

To study the cortisol levels in patients with central serous chorioretinopathy (CSCR).

METHODS

Endogenous cortisol levels in plasma and urine were determined in 44 patients with CSCR by radioimmunoassay and chromatography, and their results were compared with that of 41 controls.

RESULTS

In acute CSCR, the mean values of the plasma cortisol (296.53 +/- 77.03) ng/ml and 24-hour urine 17-hydroxysteroids (the major metabolite of cortisol metabolism) (12.08 +/- 4.82) mg/24 h revealed significantly higher values in the patient group (P < 0.05).

CONCLUSIONS

Increased levels of endogenous cortisol play a role in the development of CSCR.

[Studies on precipitate of Huanglian-Huangqin couples in decoction]

OBJECTIVE

Chemical composition of precipitate was researched when Huanglian-Huangqin was decocted.

METHOD

Ployamide column chromatography, TLC and TOF-MS were used.

RESULT

The precipitate contains berberine, palmatine, jalrorrhizing, epiberberine, copticine, baicaling and wogonoside.

CONCLUSION

The precipitate is effective composition in Chinese medical decoction. The research provides new data on medical effects of Huanglian-Huangqin couples.

Benzolactam (BL) enhances sAPP secretion in fibroblasts and in PC12 cells

Activation of protein kinase C is known to favor the alpha-secretase processing of the Alzheimer's disease (AD) amyloid precursor protein (APP), resulting in the generation of non-amyloidogenic soluble APP (sAPP). Consequently, the relative secretion of amyloidogenic Abeta1-40 and Abeta1-42(3) is reduced. This is particularly relevant since fibroblasts and other cells expressing APP and presenilin AD mutations secrete increased amounts of total Abeta and/or increased ratios of Abeta1-42(3)/Abeta1-40. Interestingly, PKC defects have been found in AD brain alpha and beta isoforms) and in fibroblasts (alpha isoform) from AD patients. Here, we use a novel PKC activator (benzolactam, BL) with improved selectivity for the alpha, beta and gamma isoforms to enhance sAPP secretion in fibroblasts from AD patients and in PC12 cells. Incubation (2 h) of AD fibroblasts with BL (1 and 10 microM) resulted in significant increases of sAPP secretion over basal levels. sAPP secretion in BL-treated AD cells was also slightly higher compared to control BL-treated fibroblasts, which only showed significant increases of sAPP secretion after treatment with 10 microM BL. Staurosporine (a PKC inhibitor) eliminated the effects of BL in both control and AD fibroblasts. BL and a related compound (LQ12) also caused an approximately 3-fold sAPP secretion in PC12 cells. The use of a novel and possibly non-tumorigenic PKC activator may prove useful to favor non-amyloidogenic APP processing and is, therefore, of potential therapeutic value.

Sulindac sulfide alters the expression of cyclin proteins in HT-29 colon adenocarcinoma cells

Sulindac sulfide (SS), the active metabolite of the colon cancer chemopreventive compound sulindac, inhibits the proliferation of HT-29 colon cancer cells mainly by inducing cell quiescence. We determined by bivariate flow-cytometric analysis both the DNA and cyclin protein content of individual cells. Thus, we assessed in detail the expression of several cyclins during the cell-cycle phases and demonstrated that SS (i) decreases the expression of cyclins B1 and E and (ii) increases the expression of cyclins D1, D2 and D3, particularly in the G1 phase of the cell cycle. SS-induced apoptotic cells expressed both E- and D-type cyclins but not cyclin B1. The changes in cyclin expression combined with reduced catalytic activity of cyclin-dependent kinases could explain in molecular terms the anti-proliferative effect of SS on HT-29 colon cancer cells. These changes may contribute to the chemopreventive effect of sulindac.

Synthesis and evaluation of a photolyzable derivative of sphingosine 1-phosphate--caged SPP

The synthesis of a photolyzable sphingosine 1-phosphate derivative is reported via the reaction of N-(tert-butoxycarbonyl)-2-N,3-O- isopropylidenesphingosine 7 and bis(alpha-methyl-o-nitrobenzyl) N,N-diisopropyl-phosphoramidite. Stimulation of DNA synthesis upon illumination of caged SPP-loaded cells is also described.

Sulindac sulfide alters the expression of cyclin proteins in HT-29 colon adenocarcinoma cells

Sulindac sulfide (SS), the active metabolite of the colon cancer chemopreventive compound sulindac, inhibits the proliferation of HT-29 colon cancer cells mainly by inducing cell quiescence. We determined by bivariate flow-cytometric analysis both the DNA and cyclin protein content of individual cells. Thus, we assessed in detail the expression of several cyclins during the cell-cycle phases and demonstrated that SS (i) decreases the expression of cyclins B1 and E and (ii) increases the expression of cyclins D1, D2 and D3, particularly in the G1 phase of the cell cycle. SS-induced apoptotic cells expressed both E- and D-type cyclins but not cyclin B1. The changes in cyclin expression combined with reduced catalytic activity of cyclin-dependent kinases could explain in molecular terms the anti-proliferative effect of SS on HT-29 colon cancer cells. These changes may contribute to the chemopreventive effect of sulindac.

Effect of aspirin on induction of apoptosis in HT-29 human colon adenocarcinoma cells

Aspirin (ASA) and other nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit colorectal tumorigenesis. Apoptosis is a critical determinant of tissue mass homeostasis and may play a role in carcinogenesis. We studied the effect of ASA on the survival of a human colon cancer cell line using more sensitive methods than we had applied previously. ASA induced apoptosis in HT-29 colon adenocarcinoma cells at concentrations > or =1 mM as established by: (a) morphological changes consistent with apoptosis in cells examined by fluorescence microscopy and semi-thin cell sections, and (b) DNA strand breaks: 45% of the cells were TdT-mediated dUTP nick end labeling (TUNEL) positive at 3 mM at 72 hr, and 70% were positive by the comet assay. Electron microscopy also confirmed the induction of apoptosis by ASA. ASA-induced apoptosis was not associated with: (a) a ladder pattern on genomic DNA electrophoresis, or (b) a subdiploid peak on flow cytometry. Apoptotic bodies were virtually absent on standard morphological assessments and only a few were detected on semi-thin sections. For the above reasons, this apoptosis induced by ASA is "atypical," and the unusual features of ASA-induced apoptosis, besides their taxonomic value, may offer clues to the mechanisms that control the process of apoptosis or perhaps the cancer chemopreventive properties of this compound. These findings demonstrate that ASA induces apoptosis in human colon cancer cells, bolstering the hypothesis that apoptosis may be a mechanism by which NSAIDs inhibit colon carcinogenesis. These findings should be examined in animal and/or clinical research studies in vivo.

Sulindac sulfide induces several subpopulations of colon cancer cells, defined by PCNA/Ki-67 and DNA strand breaks

We assessed the effect of sulindac sulfide (SS), a colon cancer chemopreventive agent, on the proliferation and apoptosis in the colon cancer cell lines HCT-15 and HT-29. We applied a triparameter flow cytometric analysis that simultaneously determined DNA content, expression of Ki-67 or proliferating cell nuclear antigen (PCNA), and extent of DNA strand breaks by TUNEL (TdT-mediated dUTP nick end labeling). HCT-15 and HT-29 cells were exposed to SS 200 microM and 175 microM, respectively, for up to 72 h. As expected, SS inhibited proliferation and induced apoptosis. SS also induced several subpopulations of cells defined by their expression of proliferation markers and DNA strand breaks. By 72 h the rapidly proliferating cells [PCNA/Ki-67(+)/TUNEL(-)] were reduced from > 90% to about one third. Of the remaining cells, about one third were apoptotic [PCNA/Ki-67(-)/TUNEL(+)] and one third were quiescent [PCNA/Ki-67(-)/TUNEL(-)]. Another subpopulation was detected that was PCNA/Ki-67(+)/TUNEL(+), some had a dominant subdiploid peak and over half were in S or G2/M phases by DNA content. Thus, a subpopulation of apoptotic cells strongly expressed PCNA and Ki-67, suggesting that their specificity as proliferation markers may need reassessment. Similar results were obtained with the HL-60 promyelocytic cell line.

Curcumin, a natural plant phenolic food additive, inhibits cell proliferation and induces cell cycle changes in colon adenocarcinoma cell lines by a prostaglandin-independent pathway

Curcumin, the active ingredient of the rhizome of the plant turmeric (Curcuma longa Linn), a commonly used spice, prevents cancer in animal tumor models. Its mechanism of action is unknown; curcumin may act by inhibiting arachidonic acid metabolism. To explore the mechanism of curcumin's chemopreventive effect, we studied its role in proliferation and apoptosis in the HT-29 and HCT-15 human colon cancer cell lines. Curcumin dose-dependently reduced the proliferation rate of both cell lines, causing a 96% decrease by 48 hours. No apoptosis was detected. The antiproliferative effect was preceded by accumulation of the cells in the G2/M phase of cell cycle. The effect of curcumin was similar in both cell lines, which, however, differ in their ability to produce prostaglandins. We conclude that curcumin inhibits colon cancer cell proliferation in vitro mainly by accumulating cells in the G2/M phase and that this effect is independent of its ability to inhibit prostaglandin synthesis. The role of curcumin's antiproliferative effect in human colon cancer remains to be established.

Cervical carcinoma cells transfected with the CD80 gene elicit a primary cytotoxic T lymphocyte response specific for HPV 16 E7 antigens

Cervical carcinoma is strongly associated with human papillomavirus (HPV) type 16, and the transforming viral genes E6 and F7 are steadily expressed by the tumor cells. Therefore these viral oncogenes may be regarded as tumor-associated antigens. Our previous studies showed that cervical cancer cells after introduction of the CD80 gene activated allogeneic cytotoxic T lymphocytes (CTLs). In this study, we tested whether HPV 16+ cervical tumor cells (CaSki) expressing CD80 were able to activate CTLs recognizing HPV 16 E7 antigen. To this end, CD80+ CaSki cells (HLA-A*0201+) were used to stimulate peripheral blood T lymphocytes from HLA-A*0201+ healthy donors. We found that the activated T cells were able to lyse parental CaSki cells as well as Epstein-Barr virus-immortalized autologous B cells loaded with HLA-A*0201-restricted E7 peptides (amino acids 11-19, 82-90, 86-93). In contrast, no lysis was observed against target cells loaded with a control HIV-reverse transcriptase peptide (amino acid 476-484, HLA-A 0201-restricted). Our data, for the first time, provide evidence that CD80-expressing cervical cancer cells are able to activate tumor-specific CTLs using HPV 16 E7 as tumor-associated antigens.

T cells of the human intestinal lamina propria are high producers of interleukin-10

BACKGROUND AND AIM

Some of the recently observed functional features characteristic of immunocompetent cells residing in the human intestinal lamina propria could be mediated by interleukin-10 (IL-10). To investigate the role of IL-10 in the human intestinal mucosa, the regulation of IL-10 production by lamina propria T lymphocytes (LPL-T) was determined and compared with that of peripheral blood T lymphocytes (PBL-T).

METHODS

Following activation by using different stimuli, IL-10 release by LPL-T and PBL-T into the supernatant was measured by enzyme linked immunosorbent assay (ELISA). In parallel, cell growth was determined by [3H]-thymidine incorporation.

RESULTS

Neither LPL-T nor PBL-T release IL-10 constitutively. Triggering through CD2 or the T cell receptor (TCR)/CD3 complex in the presence of autologous monocytes induces significantly greater IL-10 secretion by LPL-T than by PBL-T. Engagement of the CD45 receptor enhances IL-10 release and proliferation of CD2 triggered CD45RO+ PBL-T. In contrast, it reduces CD2 induced IL-10 production by LPL-T without altering cell growth significantly.

CONCLUSIONS

Activated LPL-T release relatively high amounts of IL-10. Enhanced IL-10 production by activated LPL-T, in comparison with activated PBL-T, is not only related to the presence of a higher proportion of CD45RO+ T cells in the intestinal lamina propria, but is also caused by increased sensitivity of LPL-T to CD2 co-stimulation. The differential responsiveness of LPL-T, compared with PBL-T, to CD45 engagement demonstrates that CD45 could be involved in the altered CD2 reactivity of LPL-T.

Regulation of human papillomavirus type 18 in vivo: effects of estrogen and progesterone in transgenic mice

We examined the in vivo effect of estrogen, progesterone, RU 486, and pregnancy on the upstream regulatory region (URR) of human papillomavirus (HPV) 18 transgenic mice. The mice contain the bacterial reporter beta-galactosidase gene under control of the HPV 18 URR. Pregnant transgenic mice were sacrificed on various days of gestation and the level of URR activation was determined. Another group of female transgenic mice was ovariectomized at 4 to 6 weeks of age. Pellets of estradiol, progesterone, progesterone + RU 486, or placebo were implanted 1 to 2 weeks after ovariectomy. Mice were sacrificed after pellet implantation to examine acute and chronic effects. Marked increases in URR activation during pregnancy were observed. Progesterone was found to activate the URR acutely. Significantly higher activation was demonstrated at 24 hr in the progesterone group compared to placebo (P < 0.01). Activation with progesterone at 24 hr was significantly higher than at any other time point (P < 0.001). A trend toward decreasing activation over time was demonstrated in the progesterone group (r = -0.87, P = 0.0001). RU 486 does not block the activation of progesterone in our model. Estradiol activates the URR acutely compared to placebo (P = 0.034). This in vivo model demonstrates activation of the URR in response to exogenous estrogen, progesterone, and pregnancy. These data may have clinical implications for women who harbor high-risk HPV.

[Immunohistochemical distribution of atrial natriuretic peptides in the external wall of cochlear duct of guinea pigs]

The paper presents the distribution of the atrial natriuretic peptides (ANP) in the external wall of each turn of the cochlear duct of guinea pigs by an immunohistochemical technique (ABC method). ANP immunoreactivity (ANP-IR) was found in the strial vasculayis, sprial prominence, cells of external suicus and sprial ligament of the external wall of the vestibular canal and media canal. But no positive immunoreactive products were found in the spiral ligament of the external wall of scala tympanity. The results suggest that ANP of the external wall of the cochlear duct may play an important role in the formation of endolymphe. ANP-IR was difference in spiral ligament of in these scala. But their physiological function was different.

Sulindac sulfide inhibits the proliferation of colon cancer cells: diminished expression of the proliferation markers PCNA and Ki-67

We evaluated the effect of sulindac sulfide (SS), which reduces cell number and induces apoptosis in cultured colon cancer cells (CCCs), on expression of the proliferation markers PCNA and Ki-67 in HT-29 and HCT-15 CCCs; only the former express cyclooxygenases. DNA content and PCNA/Ki-67 expression were analyzed by bivariate flow cytometry. SS inhibited cell proliferation, determined by the reduced expression of PCNA and Ki-67, roughly by half at 72 h, and induced apoptosis (accounting for about two-thirds and one-third of the reduction in cell number, respectively). A similar effect of SS occurred in HT-29 and HCT-15 CCCs, and also in non-colonic cells, indicating that this rather general effect of SS on cultured cells is not dependent on inhibition of prostaglandin synthesis.

Interferon-gamma enhances susceptibility of cervical cancer cells to lysis by tumor-specific cytotoxic T cells

Recently we have demonstrated that tumor-specific cytotoxic T lymphocytes (CTLs) can be activated by cervical carcinoma cells expressing the costimulatory molecule CD80, which may be used as a therapeutic vaccine for patients with cervical cancer. For activated CTLs to be effective, appropriate amounts of MHC class I expression are required on target tumor cells. In this study, we found that some cervical carcinoma cells expressed only low levels of MHC class I and adhesion molecules such as CD54. We further demonstrated that tumor cells (CaSki and SiHa) expressing low levels of MHC class I were more resistant to lysis by specific CTLs than tumor cells (HeLa) expressing high levels of MHC class I. Treatment of CaSki or SiHa cells with interferon-gamma resulted in an increased expression of MHC class I, MHC class II, and CD54. Expression of CD58 and CD80 was not up-regulated or induced. Treatment of the tumor cells with interferon-gamma significantly enhanced the lysis of the tumor cells by specific CTLs which had been activated by the respective CD80-expressing tumor cells. The enhancement of cytolysis could be blocked by monoclonal antibodies to MHC class I and CD54, but not by that to MHC class II. Furthermore, we found that interferon-gamma induced apoptosis in cervical carcinoma cells but not in tumor-specific CTLs.

Synthesis of novel 6-amido-6-deoxy-l-galactose derivatives as sialyl Lewis X mimetics

The synthesis and biological potency of several sialyl Lewis X (SLe(x)) mimetics is described. These mimics incorporate all of the critical functional groups present in SLe(x) necessary for binding to E-selectin. L-Galactose is used to mimic the naturally occurring L-fucose residue in SLe(x) due to the identical arrangement of the 2-, 3-, and 4-hydroxyl groups. Several synthetically and enzymatically prepared amino acids were used to mimic the D-galactose residue. Because of the variability incorporated in the synthesis of these amino acids the spatial requirements necessary for efficient binding were investigated. A carboxylate bearing side chain was introduced as a sialic acid mimic and the chain length was varied to maximize biological activity. By investigating the optimal arrangement of these two factors mimics were produced which were up twofold more active than SLe(x).

Staurosporine inhibits the proliferation, alters the cell cycle distribution and induces apoptosis in HT-29 human colon adenocarcinoma cells

Staurosporine (ST), a potent inhibitor of protein kinase C (PKC), was evaluated for its effect on the proliferation of HT-29 colon adenocarcinoma cells; PKC is associated with increased colon cell proliferation. ST inhibited cell proliferation in a time- and concentration-dependent manner by up to 90%. It also blocked the G2/M phase of the cell cycle and induced classical apoptosis (sub-diploid peak on flow cytometry, DNA ladder, and typical morphological changes). The kinetics of these changes suggest that low ST concentrations (2-20 nM) may act via a different mechanism from higher (100-1000 nM) ones. The role of ST, which is currently evaluated as an antitumor agent, in colon cancer requires further evaluation.

Effects of nonsteroidal anti-inflammatory drugs on proliferation and on induction of apoptosis in colon cancer cells by a prostaglandin-independent pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of and mortality from colon cancer. We observed that NSAIDs inhibit the proliferation rate, alter the cell cycle distribution, and induce apoptosis in colon cancer cell lines. We evaluated whether the inhibition by NSAIDs of prostaglandin (PG) synthesis is required for their effects on colon cancer cells by studying two human colon cancer cell lines: HCT-15 and HT-29. HCT-15, which lacks cyclooxygenase transcripts, does not produce PGs even when exogenously stimulated, whereas HT-29 produces PGE2, PGF2 alpha, and PGI2. HCT-15 and HT-29 cells, when treated for up to 72 hr with 200 microM sulindac sulfide (an active metabolite of sulindac) or 900 microM piroxicam, showed changes in proliferation, cell cycle phase distribution, and apoptosis. Treatment with PGE2, PGF2 alpha, and PGI2, following a variety of protocols, and at concentrations between 10(-6) and 10(-11) M, failed to reverse the effects of NSAIDs on these three parameters of cell growth. We concluded that NSAIDs inhibit the proliferation rate of the two colon cancer cell lines independent of their ability to inhibit PG synthesis. Thus, alternative mechanisms for their activity on tumor cell growth must be entertained. These observations may be relevant to the mechanism of colon tumor inhibition by NSAIDs.

Expression of CD80 enhances immunogenicity of cervical carcinoma cells in vitro

Although cervical carcinoma cells may express the human papillomavirus oncoproteins E6 and E7, they fail to induce an effective specific cytotoxic T lymphocyte response. This failure may be due to a lack of expression of costimulatory molecules, such as CD80 (B7.1). To augment the immunogenicity of cervical carcinoma cells, we transfected human papillomavirus (HPV)-transformed cell lines, CaSki and HeLa, with the CD80 expression vector pBJ. Alloantigens on the tumor cells were used for the stimulation of peripheral blood lymphocytes (PBLs). Cocultivation of PBLs and tumor cells resulted in proliferation of CD4+ and CD8+ T lymphocyte subsets. CD80-expressing tumor cells induced proliferation of allogeneic PBLs two-to sixfold compared to control cell lines. Cocultivation of allogeneic PBLs with CD80-positive tumor cells for 3 weeks gave rise to cytotoxic T cells capable of lysing untransfected parental tumor cell lines. Our results demonstrate an immunostimulatory effect of CD80 expression on cervical cancer cells, which provides a basis for the development of a therapeutic tumor vaccine.

Differential regulation of human T cell responsiveness by mucosal versus blood monocytes

Human intestinal T lymphocytes are constantly exposed to a large number of foreign antigens without developing a systemic immune response. One crucial mechanisms leading to this intestinal hyporesponsiveness is based on impaired signal transduction through the T cell receptor/CD3 complex in lamina propria T lymphocytes (LP-T). In this study, we addressed the question whether a lack of co-stimulatory/progression signals might also contribute to LP-T hyporesponsiveness. To this end, isolated human monocyte populations from the intestinal lamina propria were obtained and their phenotypes as well as their capacity to promote T cell activation studied. Here, we demonstrate that lamina propria macrophages (LP-MO), in contrast to peripheral blood monocytes (PB-MO), do not support proliferation of either LP-T or PB-T. This may be due to the low expression of ligands (CD54, CD58, CD80) for the T cell accessory receptors CD11/18, CD2 and CD28/CTLA-4 on mucosal macrophages. Thus, down-regulation of both recognition/competence and co-stimulatory/progression signals contribute to intestinal hypo- or unresponsiveness.

Nonsteroidal antiinflammatory drugs inhibit the proliferation of colon adenocarcinoma cells: effects on cell cycle and apoptosis

Aspirin and other NSAIDs reduce the incidence of and mortality from colon cancer, but their mechanism of action remains unknown. We evaluated the effect of aspirin (ASA) and three other structurally unrelated NSAIDs (indomethacin, naproxen, and piroxicam) on cell proliferation, cell cycle phase distribution, and the development of apoptosis in HT-29 colon adenocarcinoma cells in vitro. All of the NSAIDs examined reduced the proliferation and altered the morphology of these cells in a time- and concentration-dependent manner. In addition, they altered the cell cycle phase distribution of these cells. They increased the proportion of cells in the G0/G1 phase and reduced the proportion in the S phase of the cell cycle. ASA and indomethacin also reduced the percentage of cells in the G2/M phase, whereas naproxen and piroxicam did not. Parallel to their effect on cell cycle, ASA and indomethacin also reduced the levels of p34cdc2 and p33cdk2, two cyclin-dependent kinases that are important for cell cycle progression. Finally, all the NSAIDs analyzed, except ASA, induced apoptosis in these cells. There as a rough correlation between the relative potency of these compounds in inducing apoptosis and their effectiveness in retarding cell proliferation. Our findings indicate that NSAIDs can reduce the proliferation of HT-29 colon cancer cells in vitro. In addition, they cause cell cycle quiescence and apoptosis, both of which could account for their anti-proliferative effect. These findings suggest possible mechanisms for the cancer preventive effects of these compounds in humans.

Enhancers of glp-1, a gene required for cell-signaling in Caenorhabditis elegans, define a set of genes required for germline development

The distal tip cell (DTC) regulates the proliferation or differentiation choice in the Caenorhabditis elegans germline by an inductive mechanism. Cell signaling requires a putative receptor in the germline, encoded b y the glp-1 gene, and a putative signal from the DTC, encoded by the lag-2 gene. Both glp-1 and lag-2 belong to multigene gene families whose members are essential for cell signaling during development of various tissues in insects and vertebrates as well as C. elegans. Relatively little is known about how these pathways regulate cell fate choice. To identify additional genes involved in the glp-1 signaling pathway, we carried out screens for genetic enhancers of glp-1. We recovered mutations in five new genes, named ego (enhancer of glp-1), and two previously identified genes, lag-1 and glp-4, that strongly enhance a weak glp-1 loss-of-function phenotype in the germline. Ego mutations cause multiple phenotypes consistent with the idea that gene activity is required for more than one aspect of germline and, in some cases, somatic development. Based on genetic experiments, glp-1 appears to act upstream of ego-1 and ego-3. We discuss the possible functional relationships among these genes in light of their phenotypes and interactions with glp-1.

Selected eicosanoids increase the proliferation rate of human colon carcinoma cell lines and mouse colonocytes in vivo

Eicosanoids have been implicated in colon carcinogenesis, but their role remains unclear. The levels of PGE2 are elevated in colon cancer tissues and in blood draining colon tumors. The effect of eicosanoids on the proliferation of colonic cells is unknown. We studied the effect of several prostaglandins (PGs) and leukotriene (LT)B4 on the proliferation rate of the human colon adenocarcinoma cell lines SW1116 and HT-29 and of 16,16-dimethyl PGE2 (dmPGE2) on the colon of BALB/c mice. PGs E2, F2 alpha, I2, the methyl ester of PGE2, dmPGE2, and LTB4 (10(-10), 10(-8), 10(-6) M), administered for up to 72 h, stimulated cell proliferation in SW1116 cells and all but PGF2 alpha and PGI2 stimulated proliferation in HT-29 cells. The proliferative effect was time- and concentration-dependent. However, in SW1116 cells the response to PGs was 'bell-shaped', being maximal at 10(-8) M, with the 10(-10) and 10(-6) M concentrations being less effective. In HT-29 cells, the addition of methyl groups to the PGE2 molecule increased the proliferative effect. None of these eicosanoids affected the distribution of these cells in the cell cycle or their rate of programmed cell death (apoptosis). dmPGE2 stimulated 3.6-fold the proliferation of colonocytes in normal BALB/c mice. This was determined by bivariate flow cytometric analysis of the expression of proliferating cell nuclear antigen (PCNA) in virtually pure populations of mouse colonocytes. dmPGE2 did not alter the cell cycle distribution of these cells. We conclude that several PGs as well as LTB4 stimulate the proliferation of human colon carcinoma cells in vitro, while dmPGE2 has a similar effect on mouse colonocytes in vivo. These findings raise the possibility that eicosanoids may contribute to colonic carcinogenesis by stimulating the proliferation rate of tumor cells in the colon.

Sulindac sulfide, an aspirin-like compound, inhibits proliferation, causes cell cycle quiescence, and induces apoptosis in HT-29 colon adenocarcinoma cells

Nonsteroidal antiinflammatory drugs (NSAIDs), have cancer preventive and tumor regressive effects in the human colon. They lower the incidence of and mortality from colorectal cancer and sulindac reduces the number and size of polyps in patients with familial adenomatous polyposis. We studied the effect of sulindac, and its metabolite sulindac sulfide, on the proliferation of HT-29 colon adenocarcinoma cells. Both compounds reduced the proliferation rate of these cells, changed their morphology, and caused them to accumulate in the G0/G1 phase of the cell cycle. These responses were time- and concentration-dependent and reversible. In addition, these compounds reduced the level and activity of several cyclin-dependent kinases (cdks), which regulate cell cycle progression. Sulindac and sulindac sulfide also induced apoptosis in these cells at concentrations that affected their proliferation, morphology, and cell cycle phase distribution. Sulindac sulfide was approximately sixfold more potent than sulindac in inducing these cellular responses. Our results indicate that inhibition of cell cycle progression and induction of apoptotic cell death contribute to the anti-proliferative effects of sulindac and sulindac sulfide in HT-29 cells. These findings may be relevant to the cancer preventive and tumor regressive effects of these compounds in humans.

Flow cytometric characterization of proliferation-associated nuclear antigen (p105) during the cell cycle in normal lymphocytes and promyelocytic leukemia cells (HL-60)

Bivariate flow cytometric analysis of p105 expression and DNA content was performed in human lymphocytes and promyelocytic leukemia cells (HL-60). We also employed a new method of detecting DNA strand breaks associated with apoptosis by labeling the 3'-OH termini in the breaks with biotinylated dUTP in a reaction employing exogenous terminal deoxynucleotidyl transferase (TdT). Phytohemagglutin-stimulated proliferating lymphocytes express p105 maximally after 48 hours, similar to HL-60 cells in exponential growth phase. Antigen expression in G1 was notably heterogeneous in G1 phase of both cell types and highest in M-phase cells treated for 6 hours with vinblastine. However, the p105-DNA ratio changed very little. Cycloheximide did not affect P105 expression. Methotrexate decreased p105 expression. Camptothecin and teniposide induced apoptosis, but apoptotic cells still expressed p105. Dual-parameter measurement also demonstrated that TdT-positive apoptotic cells expressed p105 at a higher level than apoptotic TdT negative cells. The data on drug treatment suggest that expression of p105 may be useful in monitoring chemotherapeutic effects but not as a marker of cell death from apoptosis.

Prostaglandin E2 down-regulates the expression of HLA-DR antigen in human colon adenocarcinoma cell lines

Prostaglandins (PG) have been implicated in the pathogenesis of cancer and play an important role in immune regulation. Colon cancer is associated with elevated levels of PGE2, while aspirin, the prototypical inhibitor of PG synthesis, appears to reduce the incidence of colon cancer by 50%. We have observed that in human colon cancer the expression of HLA class I and II antigens is reduced or lost; loss of HLA antigens is suspected to be a mechanism by which the malignant cell escapes the immune surveillance. We investigated the effect of these eicosanoids on the expression of HLA antigens in human colon adenocarcinoma cell lines. PGE2 down-regulated the expression of the class II antigen HLA-DR in SW1116 cells (65% reduction at 2.8 x 10(-8) M). This effect was dose- and time-dependent, reversible, and specific (PGF2 alpha and LTB4 had no effect; the expression of carcinoembryonic antigen and class I genes were not affected). Aspirin induced the expression of HLA-DR in HT29 cells, a cell line not expressing constitutively HLA-DR. The reduction of HLA-DR by PGE2 was accompanied by reduced messenger RNA (mRNA) levels of HLA-DR alpha and reduced transcription of the corresponding gene. In contrast to HLA-DR, none of these three eicosanoids affected the expression of HLA class I genes, as assessed via determination of protein expression by fluorescence flow cytometric analysis and evaluation of the corresponding class I mRNA levels. We conclude that PGE2 specifically down-regulates the expression of HLA-DR, while it does not affect the expression of class I antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine messenger RNA expression and proliferation status of intestinal mononuclear cells in noninflamed gut and Crohn's disease

T-cell activation and local cytokine production probably contribute to the pathogenesis of Crohn's disease. This study investigates the proliferative status of intestinal mononuclear cells (MNC) and cytokine messenger RNA (mRNA) production in gut tissue sections from patients with Crohn's disease and noninflamed controls. mRNA in situ hybridization was performed using 33P-labelled riboprobes for human interleukin (IL)-1 beta, IL-2, IL-4, IL-5, IL-6, tumour necrosis factor-alpha and interferon-gamma. The expression of the proliferation-associated antigen Ki-67 was analysed by immunohistochemical single and double staining. Compared with controls, where proliferation of MNC and cytokine expression was restricted to mucosal lymphoid follicles, inflamed gut tissue contained increased numbers of cells expressing cytokine mRNA, most prominently IL-1 beta and IL-6, but also interferon-gamma and tumour necrosis factor-alpha. Proliferating T-cells were increased in number, and small amounts of IL-2-expressing cells were detected. IL-4 was expressed by a few cells exclusively in follicular germinal centres. IL-5 was negative. Proinflammatory cytokines are strongly expressed in situ in Crohn's disease and largely predominate over lymphokine mRNA. Our results provide in situ evidence of a local lymphocyte response in Crohn's disease with characteristics of a delayed-type hypersensitivity reaction.

A 170 kDa polypeptide from mung bean shares multiple epitopes with rabbit skeletal myosin and binds ADP-agarose

A 170 kDa polypeptide that has been partially purified from mung beans is retained by ADP-agarose even in the absence of divalent cations when most non-myosin ATPases and kinases do not bind. Attempts to demonstrate a myosin-like ATPase activity were inconclusive, however, and the protein accounts at most for only a small part of the total K+ EDTA ATPase activity of mung bean extracts. All four monoclonal antibodies raised to the 170 kDa polypeptide react with rabbit skeletal muscle myosin and localize the 170 kDa polypeptide in mung bean root tip cells to the actin-containing phragmoplast and to sites dispersed throughout the cytoplasm which probably include some but not all actin cables. These 4 monoclonals and 3 commercially available antimyosin monoclonals all recognise rabbit skeletal myosin and 160-170 kDa proteins that are present in two other angiosperms tested. In addition, a 158 kDa protein of mung bean reacts with only one antibody and does not bind ADP-agarose. We conclude that strong but not yet conclusive evidence points to the 160-170 kDa proteins of angiosperms being a widely conserved form of myosin heavy chain.

T cell receptor repertoire and mitotic responses of lamina propria T lymphocytes in inflammatory bowel disease

Human intestinal lamina propria T lymphocytes (LPL-T) physiologically exhibit minimal proliferation in response to antigen receptor stimulation in vitro. This is thought to occur as a consequence of regulatory influences which are exerted by the mucosal microenvironment. The present study is aimed at investigating whether proliferative responses of intestinal LPL-T to antigen receptor stimulation are altered in patients with inflammatory bowel disease. Accordingly, proliferative responses of LPL-T in patients with Crohn's disease and ulcerative colitis to stimulation with CD3 MoAb plus IL-2 were examined and compared with controls. In addition, T cell receptor (TCR) repertoires of LPL-T and peripheral blood T lymphocytes were determined by indirect immunofluorescence using a panel of 11 TCR V beta specific antibodies. In most patients with inflammatory bowel disease, LPL-T showed enhanced proliferation to antigen receptor stimulation compared with controls. Moreover, perhaps as a consequence, an enhanced frequency of in vivo preactivated T cells was seen as judged from an increased spontaneous proliferative response to low concentrations of exogenous IL-2. LPL-T and peripheral blood T lymphocytes exhibited similar percentages of TCR V beta gene usage both in controls and in patients. In summary, polyclonal activation of LPL-T due to impairment of local adjustment, i.e. insufficient down-regulation of TCR/CD3-dependent signalling processes, may contribute to the pathogenesis of inflammatory bowel disease.

Effects of suramin on expression of proliferation associated nuclear antigens in DU-145 prostate carcinoma cells

Suramin is the first putative growth factor inhibitor in clinical trial that has demonstrated antitumor activity. Bivariate flow cytometric analysis of the effects of suramin on the cell cycle was performed on DU-145 prostate carcinoma cell line. The effects of suramin on the expression of proliferation associated antigens (p145, p120, PCNA, Ki-67, and cyclin A) were also studied. At concentrations of 50-500 micrograms/ml, suramin arrested cells in G1 and decreased S-phase moderately. The expression of p145, p120, PCNA, Ki-67 and cyclin A in these cells was reduced. The data suggest that suramin not only inhibits proliferation, but also reduced the expression of proliferation associated antigens. The expression of these antigens may be considered a means to monitor suramin treatment in vivo and in vitro.

The effect of ethanol on the expression of HLA class I genes in human colon adenocarcinoma cell lines

The loss of HLA antigens by neoplastic cells may allow tumors to escape immune surveillance. We observed reduced expression of HLA antigens during human colon carcinogenesis. Since ethanol, which is associated with human colonic carcinogenesis, modulates the expression of HLA genes, we examined whether it affects the expression of HLA class I genes in human colon adenocarcinoma cell lines. Ethanol (1.7 x 10(-10) M to 1.7 x 10(-1) M), had no effect on the expression of HLA class I antigens on these colonocytes, the corresponding mRNA levels, or the expression of HLA constructs. Our findings do not support the hypothesis that ethanol may modulate the expression of HLA class I genes in human colon cancer cells.

[Clinical analysis and treatment of 68 spaced dentition cases]

One of the characteristic feature of normal occlusion is arch continuity, as expressed by proximal contact between all teeth in each dental arch.The dental arches of a consider able number of individuals show space between some,or even all,of the teeth.Such dental arches are know as spaced dentition.It is detrimental of arch integrity, esthetics and normal dental function.The purpose of this article to study distribution according to sex and age,number and location of the spaces,their etiology and principle of orthodontic treatment.In a random sample of 68 cases of the participating patients who is space greater than 0.5 millimeter between the proximal surface of adjacent teeth.The samples were divided into three age groups, the exact width of each space was measured by calipers in table.

Bivariate flow cytometric analysis of p53 and DNA content in hepatocellular carcinoma

Bivariate flow cytometric analysis of p53 protein and DNA content was studied in archival specimens of hepatocellular carcinoma (HCC) from Chinese patients and corresponding benign liver tissues from a series of 51 patients at Sun Yat-sen University of Medical Sciences. Extracted nuclei were stained with the fluoresceinated monoclonal antibody PAb 1801, which recognizes human p53 protein (mutant and wild types). The nuclei were counterstained with the DNA stain propidium iodide. They were measured on an Ortho FC-200 flow cytometer and the data acquired and analyzed with an IBM 386 personal computer using Kusuda's Get Simple and List Simple software. Of the 51 hepatomas studied, 26 (51%) were p53 positive as compared with 4 (16%) of 24 samples of benign liver tissue from the same patients (P < .0257). The S-phase fraction of p53-positive HCC (12.3 +/- 8.8%) (SD) was significantly greater (P < .05) than for p53-negative HCC (7.4 +/- 7.2%). p53 Expression did not correlate with age, sex, alpha-fetoprotein, hepatitis B surface antigen, tumor size, tumor grade or survival rate. List Simple software permitted analysis of each specimen together with its isotype control (IgG1) on the same cytogram so that p53 expression could be determined separately for the diploid and aneuploid populations of aneuploid tumors and for tumor cells of diploid tumors in the various phases of the cell cycle. Since p53 (PAb 1801) expression can withstand formalin fixation and pepsin treatment of paraffin-embedded tissues, flow cytometric analysis of archival specimens is feasible, and clinical correlations such as these may be carried out in retrospective studies of other tumors.

Effects of selected chemotherapeutic agents on PCNA expression in prostate carcinoma cell lines

Bivariate flow cytometric analysis of proliferating cell nuclear antigen (PCNA) was performed on prostate carcinoma cell lines (PC-3, DU-145). For both cell lines 100% methanol fixation provided optimal fluorescence intensity of PCNA. The ratio of PCNA/DNA increased in late G1 through early S/phase, followed by a decrease in mid- and late S and enhancement in G2/M phase. PCNA expression was increased in G2/M phase cells treated for 48 h with vinblastine. A slight decrease in PCNA expression was observed with cyclohexamide treatment. Hydroxyurea induced an increase in S-phase fraction along with enhanced PCNA expression. Methotrexate and Adriamycin had little effect on the cell cycle compartments of PC-3 or DU-145; however, methotrexate decreased PCNA expression, while Adriamycin enhanced it. Cisplatin increased S-phase in both cell lines, increasing PCNA expression in PC-3 and decreasing it in DU-145 cells. The data on the effects of drug treatment point to a dissociation between PCNA expression and S-phase fraction as calculated from the DNA distribution. In some cases, e.g., the cisplatin studies, different effects were obtained in the two different cell lines treated with the same drugs. Whether changes in PCNA expression will provide more useful information than S-phase fraction for evaluation of potential antitumor drugs is not known.

p145 expression during the cell cycle in HL-60 cell line and normal human lymphocytes: effects of camptothecin, vinblastine, cycloheximide, actinomycin D, retinoic acid and DMSO

Bivariate flow cytometric analysis of nucleolar antigen p145 was performed on quiescent and phytohemagglutinin-stimulated human lymphocytes and on a promyelocytic cell line (HL-60). Data were acquired on a FACScan flow cytometer and analyzed using LYSYS II. Quiescent lymphocytes did not express p145. PHA-stimulated proliferating lymphocytes expressed p145 maximally after 48 h, similarly to HL-60 cells in exponential growth. Antigen expression in G1 was notably heterogeneous in both cell types. The ratio of p145/DNA was highest in early S and decreased during mid and late S and remained low in G2M. p145 expression was lowest in M-phase cells treated for 6 h with vinblastine. Cycloheximide and actinomycin D had similar effects on p145 in HL-60 cells: expression of p145 gradually decreased from 1 to 6 h incubation in all phases of the cell cycle. Camptothecin did not decrease p145 expression and apoptotic cells from CAM-treated cultures still expressed p145. Retinoic acid and DMSO induced differentiation in HL-60 cells, and as this process progressed, p145 levels gradually fell until they approached isotype antibody control levels at 9 and 6 days, respectively. However, after 5 days treatment with 2 nM retinoic acid apoptotic cells appeared which still expressed p145. The data on drug treatment suggest that p145 exists in undifferentiated and proliferating cells and may not be a specific marker for malignancy, but may prove useful as a monitor of chemotherapeutic effects in cancer treatment.

[Nucleotide sequence of the toxic domain of an insecticidal protein gene from B. thuringiensis subsp. kurstaki HD-1]

Two crystal protein genes, the 5.3kb and 6.6kb class respectively, from Bacillus thuringiensis subsp. kurstaki HD-1 (B. t HD-1) had been cloned previously. Based on the classification system of Hofte and Whiteley, these two genes should belong to Cry I A (b) and Cry I A (c) gene type respectively. The nucleotide sequence of the toxic domain of this Cry I A (c) gene from B. t kurstaki HD-1 is firstly reported here and compared with that of Cry I A (c) gene from B. t HD-73 and Cry I A (b) gene from B. t HD-1.

Human intestinal mucosa alters T-cell reactivities

BACKGROUND

Compared with T cells in peripheral blood, lamina propria T lymphocytes have a low proliferative response to stimulation via the T-cell antigen receptor/CD3 complex or by protein kinase C activators yet largely preserve or even show an enhanced reactivity to CD2 and CD28 triggering. Coculture of peripheral blood T lymphocytes with intestinal mucosa supernatant leads to a similar functional behavior as found in freshly recovered lamina propria T lymphocytes. The aim of this study is to characterize the nature of substances in the mucosal supernatant responsible for downregulation of T-cell receptor-dependent signals.

METHODS

Mucosal supernatant was produced, dialyzed, digested with proteinase K, reduced by 2-mercaptoethanol or dithiothreitol, and tested for its activity on peripheral blood T lymphocytes.

RESULTS

Supernatant lost its activity after dialysis through a membrane (pore size 12,000-14,000). Digestion with proteinase K does not abolish its activity suggesting that the substances are neither proteins nor peptides. However, its effects on T lymphocyte proliferation can be reversed by reducing agents like 2-mercaptoethanol or dithiothreitol, suggesting that oxidative substances are contained in mucosal supernatants.

CONCLUSIONS

Our data support the view that mucosal substances that down-regulate antigen receptor-induced T lymphocyte proliferation are small, nonprotein, nonpeptide molecules with oxidative properties.

Biological response modifiers render tumor cells susceptible to autologous effector mechanisms by influencing adhesion receptors

Adhesion molecules such as CD2 and its ligand CD58 (LFA-3), as well as CD11a/18 (LFA-1) and CD54 (ICAM-1) regulate not only cell to cell attachment but also participate in lymphocyte activation, recirculation, and effector function including cytolytic activity towards tumor cells. We have investigated the role of CD2/CD58 and CD11a/18/CD54 interactions in cellular immune responses directed towards freshly recovered human T cell leukemias. Downregulation of CD54 and CD58 were observed to correlate with enhanced numbers of blasts in circulation and lack of susceptibility to killing by autologous cytotoxic lymphocytes. Furthermore, culturing tumor cells with recombinant TNF-alpha conditioned medium resulted in reinduction of CD54 and CD58 expression and susceptibility to lymphocyte mediated resulted in reinduction of CD54 and CD58 expression and susceptibility to lymphocyte mediated lysis in vitro. Our findings support the view that adhesion molecules play a pivotal role for tumor cell biology in vivo and stress the point that successful immunotherapy of malignant disease may be facilitated by influencing not only the immune response itself but also adhesion molecules on the malignant tumor targets.