A comparison of an open and laparoscopic appendectomy for patients with liver cirrhosis.

Liver cirrhosis is a critical factor contributing to morbidity and mortality in abdominal surgery, because patients with cirrhosis have a particularly high risk of developing bleeding, infection, and ascites. Laparoscopic appendectomy (LA) recently has gained a lot of attention around the world; however, comparisons between the benefits of LA and those of conventional open appendectomy (OA) for patients with liver cirrhosis have yet to be sufficiently compiled. In the present retrospective study, 40 patients with liver cirrhosis who were diagnosed with acute appendicitis before surgery underwent an appendectomy (OA in 25 patients and LA in 15 patients). This study focused on the operative time, amount of postoperative pain, use of analgesics, the restart of a normal diet, number of complications, length of hospital stay, and cost-effectiveness of the procedure in such patients. The amount of postoperative pain and the length of hospital stay were significantly smaller in the LA group. The mean values of the serum C-reactive protein on postoperative days 1, 3, and 7 were significantly less in the LA group. The number of wound infections and wound bleeding was also less in the LA group. The difference in the total cost of hospitalization was not significant. The cost of the operation was greater in the LA group than in the OA group, whereas the hospitalization cost in the LA group was less than that in the OA group. The results of this study suggest that LA may be superior to OA for the treatment of postoperative pain and postoperative complications for patients with liver cirrhosis. Long-term follow-up studies are still necessary, however, to determine any possible decrease in the number of late complications.

The therapeutic strategies in performing emergency surgery for gastroduodenal ulcer perforation in 130 patients over 70 years of age.

BACKGROUND/AIMS: Gastroduodenal ulcer is a very common illness in Japan. As the number of elderly persons in Japan increases the same as in Europe and America, the number of such patients requiring a gastroduodenal emergency operation has also increased. Regarding the complications of peptic ulcer, a perforation remains the most important fatal complication. The aim of this study is to investigate the operative risk factors and the long-term recurrence rates and to define the optimal surgical procedures in emergency situations in elderly patients. METHODOLOGY: From April 1988 through March 1997, 130 patients over 70 years of age with a perforated gastroduodenal ulcer (a duodenal ulcer perforation in 50 patients and a gastric ulcer perforation in 80 patients) were operated on in an emergency situation in our clinic. We investigated the following items; medical illness, preoperative risk factor, optimal surgical procedure, postoperative organ failure and the cumulative recurrence-free rates after surgical treatment. RESULTS: A significant correlation with mortality was observed in patients with established comorbidity in the following organs: lung (P = 0.03), heart (P = 0.02), kidney (P = 0.04), and diabetes (P = 0.03). The highest postoperative mortality rate was recorded in patients who underwent a simple closure of a duodenal ulcer perforation (4 patients; 26.7%), while the lowest postoperative mortality rate was recorded in patients who underwent a simple closure and vagotomy of a duodenal ulcer perforation (3 patients; 12.5%). In gastric ulcers, the mortality rate in patients with a gastrectomy was significantly higher than in patients with a simple closure. The practical application of the three risk factors (preoperative shock, delay to surgery over 24 hours, and medical illness) was shown by the progressive rise in the mortality rate with the increasing number of risk factors. Based on the 5 postoperative years after treating a perforated duodenal ulcer, the cumulative recurrence rate after a simple closure (63.6%) was significantly higher than that after a simple closure and vagotomy (38.1%) (n = 0.02) or after gastrectomy (0%) (P < 0.001). At 5 years postoperatively, the cumulative recurrence rate after a simple closure (41.2%) was significantly higher than that after a gastrectomy (15.9%) (P < 0.01). CONCLUSIONS: In conclusion, in an emergency situation, elderly patients are in a highly unfavorable prognostic condition due to their advanced age, and comorbidity, which thus leads to poorer results, not only worldwide, but also in Japan. Based on our findings, in duodenal ulcer cases, a simple closure and vagotomy is recommended because of its low mortality and minimal stress, except for cases with a giant perforation measuring over 20 mm in diameter at the perforation hole or with severe duodenal stenosis. In stomach ulcer cases, a gastrectomy may be recommended because of its low recurrence rate.

Murine ortholog of ASC, a CARD-containing protein, self-associates and exhibits restricted distribution in developing mouse embryos.

ASC (apoptosis-associated speck-like protein containing a CARD) was first identified as a cytosolic soluble protein that forms insoluble aggregates and enhances etoposide-induced apoptosis. We have cloned a murine ortholog of ASC (mASC) comprising 193 amino acids with a well-conserved pyrin N-terminal homology domain and caspase recruitment domain (CARD). mASC fused with green fluorescent protein appeared as a speck in transfected COS-7 cells and showed self-association. We analyzed mASC gene expression in developing embryos by in situ hybridization and found it to have a restricted distribution in mouse embryos. At E9.5, mASC was strongly expressed in the telencephalon, thalamic areas of the diencephalon, heart, and liver. Northern blotting analysis revealed that the mASC gene was expressed ubiquitously in multiple organs in adult mice. These findings indicate that mASC shows conservation of not only the primary structure of human ASC but also the ability to aggregate and has some similarity in its distribution to other CARD-containing molecules, including the apoptosis regulator Apaf-1.

La autoantigen is cleaved in the COOH terminus and loses the nuclear localization signal during apoptosis.

La autoantigen is a 47-kDa nuclear protein that binds to nascent polymerase III transcripts and a number of viral RNAs. We show that La protein was cleaved to generate a 43-kDa fragment during apoptosis of human leukemic HL-60 cells treated with camptothecin or etoposide. Immunofluorescence microscopy showed that the La protein level was increased in the cytoplasm during apoptosis of HL-60 cells. In addition, UV irradiation of HeLa cells led to the cleavage and redistribution of La protein upon apoptosis. Several lines of evidence show that La protein is cleaved by caspase-3 or closely related proteases at Asp-374 in the COOH terminus. When the full-length (La) and COOH-terminally truncated (La delta C374) forms of La protein were expressed as fusion proteins with green fluorescence protein (GFP), GFP-La delta C374 was predominantly cytoplasmic, whereas GFP-La was localized in the nucleus. These results suggest that La protein loses the nuclear localization signal residing in the COOH terminus upon cleavage and is thus redistributed to the cytoplasm during apoptosis.

ASC, a novel 22-kDa protein, aggregates during apoptosis of human promyelocytic leukemia HL-60 cells.

The cytoskeletal and/or nuclear matrix molecules responsible for morphological changes associated with apoptosis were identified using monoclonal antibodies (mAbs). We developed mAbs against Triton X-100-insoluble components of HL-60 cells pretreated with all-trans retinoic acid. In particular, one mAb recognized a 22-kDa protein that exhibited intriguing behavior by forming an aggregate and appearing as a speck during apoptosis induced by retinoic acid and other anti-tumor drugs. Cloning and sequencing of its cDNA revealed that this protein comprises 195 amino acids and that its C-terminal half has a caspase recruitment domain (CARD) motif, characteristic of numerous proteins involved in apoptotic signaling. We referred to this protein as ASC (apoptosis-associated speck-like protein containing a CARD). The ASC gene was mapped on chromosome 16p11.2-12. The antisense oligonucleotides of ASC were found to reduce the expression of ASC, and consequently, etoposide-mediated apoptosis of HL-60 cells was suppressed. Our results indicate that ASC is a novel member of the CARD-containing adaptor protein family.

Induction of autocrine factor inhibiting cell motility from murine B16-BL6 melanoma cells by alpha-melanocyte stimulating hormone.

We have previously reported that neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) successfully inhibited Matrigel invasion and haptotactic migration of B16-BL6 melanoma cells towards both fibronectin and laminin without affecting their growth. In the present study, we investigated the inhibitory mechanism of tumor cell motility by alpha-MSH. Alpha-MSH significantly blocked the autocrine motility factor (AMF)-enhanced cell motility. However, alpha-MSH did neither prevent the secretion of AMF from B16-BL6 cells nor alter the expression level of AMF receptor (gp78). On the other hand, alpha-MSH induced the secretion of the motility inhibitory factor(s) from B16-BL6 cells in a concentration- and time-dependent manner. The induction of the motility inhibitor(s) was proportional to increasing levels of intracellular cAMP induced by alpha-MSH as well as forskolin, and the activity was abolished by an adenylate cyclase inhibitor, 2',5'-dideoxyadenosine (DDA). The motility-inhibiting activity in conditioned medium (CM) from alpha-MSH-treated B16-BL6 cells was found to have a m.w. below 3 kDa after fractionation. This activity was abolished by boiling but insensitive to trypsin. The treatment of tumor cells with cycloheximide reduced the activity in alpha-MSH-stimulated CM. Our results suggest that alpha-MSH inhibited the motility of B16-BL6 cells through induction of autocrine factor(s).

A new pseudo-peptide of Arg-Gly-Asp (RGD) with inhibitory effect on tumor metastasis and enzymatic degradation of extracellular matrix.

A series of pseudo-peptide analogs of the Arg-Gly-Asp (RGD) sequence of fibronectin have been synthesized, and their anti-metastatic effects in mice and inhibitory effects on tumor cell invasion in vitro have been examined. The partially modified retro pseudo-peptide of RGD, Rrev-COCH2CO-D (FC-63), was more effective in inhibiting tumor metastasis than the original RGDS peptide. Replacement of the malonyl moiety of FC-63 with a carboxyethylene linkage (Rrev-COCH2CH2-D, FC-303 ) achieved more potent inhibition of lung metastasis of melanoma cells than FC-63. Among the analogs, FC-336, a p-xylylendiamine derivative having two FC-303 moieties, showed the most potent inhibitory effect on experimental lung metastasis produced by i.v. co-injection with B16-BL6 melanoma or colon 26 M3.1 cells in a dose-dependent manner. Multiple administrations of FC-336 after tumor inoculation also showed efficient therapeutic potency against spontaneous lung metastasis of B16-BL6 melanoma in mice. Furthermore, FC-336 effectively inhibited the invasion, migration and adhesion of tumor cells in vitro, but its inhibitory effects were not more than those of RGDS peptide. Zymography analysis revealed that FC-336 inhibited the degradation of gelatin substrate by matrix metalloproteinases (MMPs) produced by tumor cells, while the RGDS peptide did not affect the enzymatic degradation. These findings indicate that the pseudo-peptides of the RGD sequence, possessing the inhibitory property of the degradation by MMPs differently from original RGD-containing peptides, may be advantageous and useful in preventing tumor metastasis.

Inhibitory effect of vasoactive intestinal polypeptide (VIP) on experimental liver metastasis by murine colon 26-L5 carcinoma cells.

We previously reported that vasoactive intestinal polypeptide (VIP) significantly inhibited Matrigel invasion and haptotactic migration of murine colon 26-L5 carcinoma in vitro. To extend our study, we investigated the inhibitory mechanisms of VIP on Matrigel invasion of colon 26-L5 carcinoma, and the effect on metastatic properties of the tumor cells. VIP inhibited the invasion of the tumor cells in a concentration-dependent manner without affecting their growth, and achieved approximately 50% reduction at 10(-6) M. VIP also suppressed cell motility with a similar inhibition rate to the invasion assay. Time course study revealed that the motility was reduced by 40% when the tumor cells were preincubated with 10(-6) M VIP for 3 h. In contrast, 6-h pretreatment with 10(-6) M VIP caused the increased ability of the adhesion to both fibronectin and laminin with a 50% enhancement. A large amount of VIP1 receptor transcripts was expressed in the cells, whereas VIP2 receptor was undetectable, by RT-PCR and subsequent Southern blot hybridization. A specific antagonist for VIP1 receptor reversed the suppressed motility induced by VIP. Cryostat sections showed that the 3-h pretreatment of tumor cells with VIP caused the reduction of the arrest in the livers at 6 h after the tumor inoculation into a portal vein of mice. VIP could prevent the experimental liver metastasis of the tumor cells in a dose-dependent manner. The cells pretreated with 10(-6) M VIP for 3 h also showed the reduced ability of the liver metastasis. These results suggest that VIP could block the invasion and the metastasis of colon 26-L5 carcinoma through suppression of their motility.

Differential effect of intestinal neuropeptides on invasion and migration of colon carcinoma cells in vitro.

We investigated the effect of neuropeptides, which are vasoactive intestinal polypeptide (VIP), substance P, (SP), neuropeptide Y (NPY), neurokinin A (NKA), somatostatin (SOM), calcitonin gene-related peptide (CGRP), and leucine-enkephalin (L-ENK), on the invasion of murine Colon 26-L5 adenocarcinoma cells through a reconstituted basement membrane (Matrigel) using a Transwell cell culture chamber assay. VIP, SP, NPY, and L-ENK reduced invasive potential of tumor cells in a concentration-dependent manner, whereas SOM, CGRP, and NKA had no effect. Especially, VIP showed the most effective in inhibiting tumor invasion, and achieved 50% reduction at 10(-6) M. A similar effect by VIP was also observed in cell migration to fibronectin. VIP had no effect on the growth of tumor cells at the concentrations ranging from 10(-10) to 10(-6) M. The suppressed ability of the tumor cell motility by VIP (10(-6) M) was practically recovered by co-treatment with 2',5'-dideoxyadenosine, an adenylate cyclase inhibitor. These results indicate that VIP, among the neuropeptides used, could inhibit Matrigel invasion of Colon 26-L5 carcinoma cells through partial suppression of their motility, and the reduction was associated with an intracellular cAMP-mediated pathway.

Alpha-melanocyte-stimulating hormone blocks invasion of reconstituted basement membrane (Matrigel) by murine B16 melanoma cells.

We have examined the effect of alpha-melanocyte-stimulating hormone (alpha-MSH) on invasive ability of murine melanoma cell lines with different metastatic potential in a Matrigel invasion assay. alpha-MSH potently blocked the invasion of B16-BL6 cells with highly metastatic potential in a concentration-dependent manner, whereas it was less effective in inhibiting the invasion of weakly metastatic B16-F1 cells. Pretreatment of B16-BL6 cells with alpha-MSH resulted in a decrease of the adhesiveness to fibronectin and laminin substrates in a time-dependent fashion. As assessed by zymographic analysis, alpha-MSH partially inhibited the production of matrix metalloproteinase (MMP)-2 and -9 from both cell lines to a similar degree without affecting the degradative activity of these MMPs. alpha-MSH was more potent in inhibiting the migration of B16-BL6 cells towards both fibronectin- and laminin-coated substrates than that of B16-F1 cells. The growth and morphology of B16-BL6 cells were not changed after a 7-day incubation with alpha-MSH. The number of lung tumor colonies markedly decreased when B16-BL6 cells were coinjected intravenously with 10(-6) M alpha-MSH. However, alpha-MSH had no effect on the experimental lung metastases by B16-F1 cells. These results suggest that alpha-MSH suppressed the invasive and metastatic properties of B16 melanoma cells, and the degree of inhibition was associated with metastatic potential of B16 melanoma cells.

Differential effect of intestinal neuropeptides on invasion and migration of colon carcinoma cells in vitro.

We investigated the effect of neuropeptides, which are vasoactive intestinal polypeptide (VIP), substance P, (SP), neuropeptide Y (NPY), neurokinin A (NKA), somatostatin (SOM), calcitonin gene-related peptide (CGRP), and leucine-enkephalin (L-ENK), on the invasion of murine Colon 26-L5 adenocarcinoma cells through a reconstituted basement membrane (Matrigel) using a Transwell cell culture chamber assay. VIP, SP, NPY, and L-ENK reduced invasive potential of tumor cells in a concentration-dependent manner, whereas SOM, CGRP, and NKA had no effect. Especially, VIP showed the most effective in inhibiting tumor invasion, and achieved 50% reduction at 10(-6) M. A similar effect by VIP was also observed in cell migration to fibronectin. VIP had no effect on the growth of tumor cells at the concentrations ranging from 10(-10) to 10(-6) M. The suppressed ability of the tumor cell motility by VIP (10(-6) M) was practically recovered by co-treatment with 2',5'-dideoxyadenosine, an adenylate cyclase inhibitor. These results indicate that VIP, among the neuropeptides used, could inhibit Matrigel invasion of Colon 26-L5 carcinoma cells through partial suppression of their motility, and the reduction was associated with an intracellular cAMP-mediated pathway.

Simultaneous flow injection determination of iron(III) and vanadium(V) and of iron(III) and chromium(VI) based on redox reactions.

A flow injection analysis (FIA) method is presented for the simultaneous determinations of iron(III)-vanadium(V) and of iron(III)-chromium(VI) using a single spectrophotometric detector. In the presence of 1,10-phenanthroline (phen), iron(III) is easily reduced by vanadium(IV) to iron(II), followed by the formation of a red iron(II)-phen complex (lambda(max) = 510 nm), which shows a positive FIA peak at 510 nm corresponding to the concentration of iron(III). On the other hand, in the presence of diphosphate the reductions of vanadium(V) and/or chromium(VI) with iron(II) occur easily because the presence of diphosphate causes an increase in the reducing power of iron(II). In this case iron(II) is consumed during the reaction and a negative FIA peak at 510 nm corresponding to the concentration of vanadium(V) and/or chromium(VI) is obtained. The proposed method makes it possible to obtain both positive (for iron(III)) and negative (for vanadium(V) or chromium(VI)) FIA peaks with a single injection.

[Two cases of liver scar that was examined by biliary scintigraphy].

36-year-old-female admitted because of jaudice and ascites. T-bil was 18.5 mg/dl and transaminase, ALP, LDH and gamma-GTP was elevated. Ultrasonography (US) showed that right lobe was atrophy and left lobe was swelling. Plain computed tomography (CT) showed right lobe was low density. Magnetic resonance (MR) finding was T1-weighted image of right lobe was low intensity and T2-weighted image was high intensity. Angiography showed right lobe was more stained than left lobe. Histologically, right lobe was massive necrosis. These findings suggested that right lobe was liver scar. Biliary imaging showed right lobe was delayed. A 23-year-old-female admitted because of fever and abdominal tumor. Transaminase was normal, only gamma-GTP was elevated. US, plain CT, enhanced CT, MR imaging finding was as same as that of the first case. Similarily, biliary scintigraphy showed right lobe was delayed. Causes of the two liver scars was not clear, whereas liver scar detected after delivery was rare case.

The effects of pravastatin, an HMG-CoA reductase inhibitor, on cell viability and DNA production of rat hepatocytes.

Some metabolites and products of mevalonic acid are involved in various cellular functions, particularly cell growth. In this study, we assessed the effects of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on cell viability and DNA production of rat hepatocytes stimulated with epidermal growth factor. Pravastatin (0.1 to 10 microM) induced a dose-dependent reduction of DNA synthesis, assessed by 3H-thymidine incorporation in rat hepatocytes, which dropped by approximately 60% at a drug concentration of 10 microM. This suppression of DNA synthesis was nearly reversed by exogenous mevalonic acid, but was not prevented by purified low-density lipoprotein cholesterol. Pravastatin did not affect the mitochondrial reduction of Dimethylthiazolyl-diphenyl-tetrazolium bromide (MTT), but induced apoptotic change as assessed by nuclear chromatin staining. This apoptotic change was also reversed by exogenous mevalonic acid. These results indicate that mevalonic acid metabolites are necessary for DNA synthesis by rat hepatocytes stimulated by epidermal growth factor and for suppressing cell death.

Inhibition of nitric oxide production increases dimethylnitrosamine-induced liver injury in rats.

Intravascular coagulation is involved in the development of certain types of liver injury, including that induced by dimethylnitrosamine. Nitric oxide inhibits platelet aggregation and adhesion; however, its role in protecting against intravascular coagulation has not been clarified. We therefore investigated the effect of blocking the production of NO in a dimethylnitrosamine-induced liver injury model. Wistar male rats received dimethylnitrosamine (50 micrograms/kg) intraperitoneally, and were treated with N omega-nitro-L-arginine, an inhibitor of nitric oxide synthase, or N omega-nitro-D-arginine, an inactive isomer. Each arginine derivative (40 mg/kg) was injected intraperitoneally every 6 h. Twenty-four hours after dimethyl-nitrosamine administration, we observed a significant increase in the serum level of alanine aminotransferase in the N omega-nitro-L-arginine group compared with the N omega-nitro-D-arginine group. The N omega-nitro-L-arginine-treated group also exhibited a significant reduction in platelet count, a prolongation of prothrombin time, and an elevation of plasma soluble fibrin monomer complex levels. Sinusoidal congestion, intravascular coagulation, and coagulation necrosis around the central veins were prominent in the N omega-nitro-L-arginine group. In conclusion, the inhibition of nitric oxide production exacerbated the hepatic damage induced by dimethylnitrosamine, mediated by the acceleration of intravascular coagulation.

Mechanisms of cyclophosphamide-induced tolerance to IE-encoded alloantigens--evidence of clonal deletion in MHC antigen-reactive cells for skin allograft rejection.

Transplantation tolerance across H-2D plus IE antigen barriers has been achieved when B10.Thy1.1 (Kb, IAb, IE-, Db; Thy1.1) mice were primed i.v. with 9 x 10(7) spleen cells plus 3 x 10(7) bone marrow cells from B10.A(5R) (Kb, IAb, IEb, Dd; Thy1.2) and treated i.p. with 200 mg/kg of cyclophosphamide (CP) two days later. The tolerant state was confirmed by prolonged acceptance of donor-type skin grafts, and in vitro unresponsiveness to donor antigens. From the early stage of tolerant state, V beta 11+ or V beta 5+ T cells expressing CD4 or CD8 accessory molecules were markedly decreased in the periphery of the tolerant mice. Moreover, neither CD4+CD8- nor CD4-CD8+ thymocytes bearing a high density of V beta 11 or V beta 5 were detected in the chimeric thymus. The intrathymic clonal deletion appeared to be maintained in some of the recipient mice even after the disappearance of detectable mixed chimerism in the late stage. These results suggest that the mechanisms of the CP-induced tolerance include the destruction of the IE (and probably H-2D) reactive T cells in the periphery followed by the intrathymic clonal deletion of T cells reactive against these antigens. These results directly show the strong correlation between transplantation tolerance to H-2 alloantigens and the disappearance of alloreactive T cells in both the periphery and thymus.

[A case of non-insulin-dependent diabetes mellitus associated with diabetic ketoacidosis after the onset of hyperlipidemia and acute pancreatitis following alcohol abuse].

We report here a case of diabetic ketoacidosis associated with hyperlipidemia and acute pancreatitis following alcohol abuse. A 23-year-old man was admitted to the hospital because of right upper abdominal and back pain developing into a state of unconsciousness and shock. He had been drinking 720 ml of whisky daily for 4 years. Laboratory data on admission revealed metabolic acidosis (pH 7.01, PaO2 84.6 mmHg, PaCO2 41.1 mmHg, HCO3- 16.3 mmol/l, BE-16.4 mmol/l), a high blood glucose level (640 mg/dl), strongly positive urinary ketone bodies, hypercholesteremia (913 mg/dl) and hypertriglyceridemia (8500 mg/dl). Furthermore, the levels of pancreatic enzyme including serum amylase (770 U/l) and elastase I (2721 ng/dl) were elevated. After successful treatment of the diabetic ketoacidosis with insulin and fluid supplementation, serum cholesterol, triglyceride and pancreatic enzyme levels decreased concomitantly with stabilization of the blood glucose level. From these findings, it is suggested that hyperlipidemia might have caused the acute pancreatitis which developed into diabetic ketoacidosis in this patient.

Evidence for involvement of clonal anergy in MHC class I and class II disparate skin allograft tolerance after the termination of intrathymic clonal deletion.

Mechanisms of cyclophosphamide (CP)-induced tolerance to class I (D) and class II (IE) alloantigens were studied. Transplantation tolerance across H-2D plus IE Ag-barriers has been achieved when B10.Thy-1.1 (Kb,IAb,IE-,Db; Thy-1.1) mice were primed i.v. with 9 x 10(7) spleen cells plus 3 x 10(7) bone marrow cells from B10.A(5R) mice (5R; kb,IAb,IEb,Dd; Thy-1.2) and treated i.p. with 200 mg/kg of CP 2 days later. The tolerant state in the early and the late stage was confirmed by prolonged acceptance of donor-type skin grafts, and in vitro unresponsiveness to donor Ag. In the tolerant B10.Thy-1.1 mice treated with 5R cells 28 days earlier and followed by CP, intrathymic clonal deletion of V beta 11+ T cells reactive to IE-encoded antigens was observed in association with intrathymic mixed chimerism. 5R skin survived, however, even after the clonal deletion of V beta 11+ T cells terminated by 180 days after tolerance induction. V beta 11+ T cells, which reappeared in the periphery of the recipient B10.Thy-1.1 mice bearing 5R skin at this stage, were not capable of proliferating in response to receptor cross-linking with V beta 11-specific mAb. Furthermore, the CTL activity against class I (Dd) alloantigens of spleen cells from these tolerant mice was restored by the addition of IL-2 to MLC. Thus, our experiments provide direct evidence that tolerance to both class I (Dd) and class II (IEb) alloantigens by clonal allergy occurs during the termination of intrathymic clonal deletion. These results clearly show practical hierarchy of the mechanisms of transplantation tolerance.

'Radioresistant' CD4-CD8- intrathymic T cell precursors differentiate into mature CD4+CD8- and CD4-CD8+ T cells. Development of 'radioresistant' CD4-CD8- intrathymic T cell precursors.

Using lectin (PNA) and monoclonal antibodies for Pgp-1, IL-2R, H-2k, CD3, and F23.1 (T cell receptor V beta 8), we characterized the 'radioresistant' CD4-CD8- double negative thymocytes at an early stage after 800 rad irradiation. Most of the CD4-CD8- cells on day 8 after irradiation expressed a high level of Thy-1, H-2k, and PNA, while a small proportion of these cells were CD3+ and/or F23.1+. The appearance of Pgp-1 and IL-2R on the 'radioresistant' double negative precursors was also sequentially examined from day 5 to day 9 after irradiation. The double negative thymocytes at day 5 expressed the highest level of Pgp-1 antigens and these cells gradually decreased in number from day 7 to day 9. By contrast, IL-2R was transiently expressed on the double negative cells on the day 7 and 8 after irradiation. These results indicate that progression of thymocyte development occurred within the CD4-CD8- thymocytes after irradiation. We further examined the homing ability of the double negative 'radioresistant' intrathymic T cell precursors to the periphery by intrathymic cell transplantation method. The double negative thymocytes proliferate and differentiate into CD4+CD8+ cells and CD4+CD8- cells but few CD4-CD8+ cells in the thymus, while only CD4-CD8+ cells were detected in the peripheral lymphoid organs 14 days after intrathymic transplantation of the double negative cells in the H-2 compatible Thy-1 congenic mice. These results suggest that the 'radioresistant' intrathymic precursors differentiate and mature in the thymus and migrate to the periphery.

The expression and sequences of T cell antigen receptor beta-chain genes in the thymus at an early stage after sublethal irradiation.

The sequential appearance of the thymocyte subpopulations and TCR gene messages occurred in the thymus of AKR mice (H-2k, Mlsa) from 7 to 14 days after sublethal irradiation. The thymocytes on day 7 after irradiation were composed of a large number of CD4+CD8+ blast-like cells and a relatively high proportion of CD4-CD8- cells (15 to 25%) but few CD3highCD4+CD8-/CD4-CD8+ cells. Approximately 22% of the CD4-CD8- cells were CD3high and -27% of the CD3highCD4-CD8- cells (-6% of whole CD4-CD8- cells) were F23.1+. The thymocytes on day 7 expressed a large amount of gamma- and delta-chain gene transcripts but reduced levels of alpha- and beta-chain gene transcripts. The V gene repertoire of 18 functional beta-chain cDNA derived from the thymocytes on day 7 was compared with those of 20 functional beta-chain cDNA derived from the thymocytes on day 14 which were composed of a large number of CD3lowCD4+CD8+ small-sized cells and a small number of CD3highCD4+CD8- cells. It is noteworthy that the distribution of V beta genes expressed in the thymocytes on day 7 was much the same as that in the thymocytes on day 14 but significantly different from that in normal BALB/c thymocytes as previously described. Interestingly, neither V beta 8.1 nor V beta 6 genes, which are important for recognition of the product of the Mlsa locus, was detected in these two cDNA libraries. These results suggest that clonal selection of TCR V beta repertoire, irrespective of positive or negative selection, appears to occur at the early stage of T cell differentiation, i.e., on the blast-like CD4+CD8+ thymocytes.