Prognostic value of vascular endothelial growth factor expression in gastric carcinoma

BACKGROUND

Many studies have shown that angiogenesis plays an important role in the growth, progression, and metastasis of solid tumors. Recently, several angiogenic factors have been identified. Vascular endothelial growth factor (VEGF) is thought to be one such angiogenic factor and is also thought to be a selective mitogen for endothelial cells. We investigated the correlation between the expression of VEGF and the progression of gastric carcinoma.

METHODS

One hundred twenty-nine specimens resected from patients with gastric carcinoma were investigated by staining with a polyclonal antibody against VEGF. Correlations between the expression of VEGF, microvessel density, and various clincopathologic factors were studied.

RESULTS

Microvessel density, determined by immunostaining for Factor VIII related antigen, was significantly higher in VEGF-positive tumors than in VEGF-negative tumors. VEGF positivity was correlated with vessel involvement, lymph node metastasis, and liver metastasis. Moreover, patients with VEGF-positive tumors had a significantly poorer prognosis than those with VEGF-negative tumors. Multivariate analysis indicated that the expression of VEGF is an independent prognostic factor in patients with gastric cancer. According to the mode of recurrence, the frequency of hepatic metastases was significantly increased among patients with VEGF-positive tumors.

CONCLUSIONS

The expression of VEGF may be a good prognostic indicator for patients with gastric carcinoma and may also be useful as a predictor of the mode of recurrence in patients with gastric carcinoma.

Emerin deficiency at the nuclear membrane in patients with Emery-Dreifuss muscular dystrophy

Mutations in the STA gene at the Xq28 locus have been found in patients with X-linked Emery-Dreifuss muscular dystrophy (EDMD). This gene encodes a hitherto unknown protein named 'emerin'. To elucidate the subcellular localization of emerin, we raised two antisera against synthetic peptide fragments predicted from emerin cDNA. Using both antisera, we found positive nuclear membrane staining in skeletal, cardiac and smooth muscles in the normal controls and in patients with neuromuscular diseases other than EDMD. In contrast, a deficiency in immunofluorescent staining of skeletal and cardiac muscle from EDMD patients was observed. A 34 kD protein is immunoreactive with the antisera--the protein is equivalent to that predicted for emerin. Together, our findings suggest the specific deficiency of emerin in the nuclear membrane of muscle cells in patients with EDMD.

Cloning and expression of Xenopus laevis xSox12 cDNA

A family of SRY-related genes has been termed SOX. We have isolated and sequenced a cDNA encoding xSox12 from Xenopus laevis ovary. The cDNA contained an open reading frame (ORF) coding for 470 amino acids encompassing an HMG box characteristic of the SOX family, a leucine zipper motif and glutamine-rich segments. The size of the xSox12 mRNA was determined to be 3.0 knt by Northern analysis. The ovary was the most prominent in the expression of the Sox mRNA among the various tissues of adult frog as far as examined.

To what extent does a given heart rate correlate with following heart rates in the developing human fetus?

To quantitatively determine the extent to which a given heart rate correlates with the following heart rate(s) at any gestational age, we studied 181 uncomplicated human fetuses between 23 and 41 weeks gestation. A continuous 90-120 min observation was made for each case using external Doppler-ultrasound cardiotocography. For every individual fetal heart rate dataset, 'probability distribution matrices' were calculated with fetal heart rates (termed FHRs) at 1-beat/min (bpm) intervals, and the beat-to-beat(s) difference (termed DFHRn: 1 < or = n < or = 1000), also at 1-bpm intervals arranged in rows and columns, respectively, with probability in each element. Using 'piecewise linear regression', (1) the difference between the DFHR1 (n = 1) probability distribution matrix as the 'control' and a given DFHRn (n > or = 2) probability matrix as the 'variable', was analyzed to obtain the statistically critical point(s) (termed 'beat-delay' in beats) for each fetus, and (2) a scattergram of 'beat-delay' vs. gestational age-group, made from all fetuses studied, was analyzed to reveal any critical age(s) in gestation. One statistically significant point was evident at 28-29 weeks gestation. During the period prior to the critical point, a linear decrement in 'beat-delay' with 21 beats (mean) at 23-25 weeks to 11 beats at 28-29 weeks gestation was noted, suggesting that the conduction system-oriented heart beat gradually comes under functional control of the autonomic nervous system as well as under possible regulation by the maturating medulla oblongata. From the critical point, through to term, there was no significant change in 'beat-delay' ranging from 7-11 beats, thereby implying that the fetal heart rate becomes stabilized as a result of the control rendered by the more developed autonomic nervous system function. Whether or not brain function cephalad to the medulla oblongata actually participates in this phenomenon remains to be elucidated.

Prolonged survival of rat hepatic allografts pretreated with a single donor-specific blood transfusion: the distribution of donor cells expressing class I major histocompatibility complex antigens in the recipient

We previously reported that a pretransplant transfusion of either ACI strain rat donor blood or PVG.r1 strain blood, which shares only the RT1.A class I major histocompatibility complex (MHC) region with an ACI donor, significantly prolonged the survival of ACI-to-LEW rat hepatic allografts, suggesting that the class I MHC antigens can be immunosuppressive in rat hepatic allografts. The distribution of the donor cells expressing RT1.Aa class I MHC antigens in the recipients was investigated using a MN4-91-6 mouse anti-rat class I (RT1.Aa) MHC monoclonal antibody. The donor class I MHC-positive cells accumulated mainly in the splenic white pulp and lymph nodes at 12 and 24 hr after blood transfusion, while very few cells were seen in the thymus, liver, lungs, and kidneys. The number of cells began to decrease in the splenic white pulp and lymph nodes at 24 hr after transfusion. This may indicate the destruction of donor cells by the recipient cells. Within 48 hr after transfusion, most cells disappeared from the recipient tissue. In an attempt to study the role of the spleen in inducing immunological unresponsiveness, a splenectomy was performed at the time of transplantation and this abrogated the prolongation of hepatic allograft survival in the recipients which received the donor blood. These findings suggest that the presence of class I MHC-positive cells in the splenic white pulp, a T-dependent area, may play an important role in inducing immunological unresponsiveness.

Uncoupling between cortical glucose metabolism and blood flow after ibotenate lesion of the rat basal forebrain: a PET study

We evaluated the cerebral metabolic rate of glucose (CMRGlu) and cerebral blood flow (CBF) after unilateral lesioning of the rat basal forebrain cholinergic projection system using ibotenic acid. Using positron emission tomography, we measured CMRGlu and CBF with [18F]-2-fluoro-2-deoxy-D-glucose (FDG) and with H2(15)O, respectively. Three days after surgery, CMRGlu and k3* (the rate constant for the phosphorylation of FDG) were reduced in the frontal cortex on the ibotenic acid-injected side, whereas CBF and K1* (the rate constant for the FDG transport from the plasma to brain) in the same rats remained in the normal range. It is concluded that the decreased cortical CMRGlu after the lesion of the cholinergic system projecting from the basal forebrain is due to the diminished neural activity rather than to decreased CBF.

The expression of truncated MK in human tumors

Midkine (MK) is a heparin binding growth/differentiation factor different from fibroblast growth factors (FGFs), and is largely composed of two domains which are found by a folded polypeptide chain interconnected by disulfide bridges. Polymerase chain reaction revealed the presence of a short MK mRNA in 7 among 12 human tumor cells which expressed MK mRNA. All of 4 pancreatic carcinoma cell lines expressed the short species in addition to the full size mRNA. The short mRNA lacked an exon and resulted in the lack of a more N-terminally located domain. The truncated form of MK was found also in some surgically removed specimens of human tumors, but not in noncancerous tissue.

Postoperative adjuvant randomised trial comparing chemoendocrine therapy, chemotherapy and immunotherapy for patients with stage II breast cancer: 5-year results from the Nishinihon Cooperative Study Group of Adjuvant Chemoendocrine Therapy for Breast Cancer (ACETBC) of Japan

Between 1985 and 1988, the effect of using ftorafur (FT) or PSK (an immunotherapy agent) in combination with the conventional postoperative adjuvant therapy using mitomycin (MMC) plus tamoxifen (TAM) was assessed in stage II, oestrogen receptor-positive (ER+) breast cancer patients. Furthermore, in ER- breast cancer stage II patients, the effects of postoperative adjuvant therapy using MMC plus FT were compared with the effects of postoperative adjuvant therapy using MMC plus PSK. Patients had primary stage II breast cancer and had undergone total mastectomy plus axillary dissection or more radical surgery. On the day of surgery, MMC (13 mg/m2) was administered intravenously. Then, ER+ patients received one of three regimens of drug therapy, starting 2 weeks after surgery: regimen A (daily oral treatment with 30 mg of TAM), regimen B (daily oral treatment with 30 mg of TAM and 600 mg of FT) or regimen C (daily oral treatment with 30 mg of TAM and 3 g of PSK) [corrected]. ER- patients received either regimen D (daily oral treatment with 600 mg of FT) or regimen E (daily oral treatment with 3 g of PSK), starting 2 weeks after surgery. Of the 540 ER+ patients registered, 525 were evaluated. The 5-year overall survival rate for ER+ patients was higher for patients who received regimen B (94.2%) than for those who received regimen A (86.9%) or regimen C (89.9%) (P = 0.063). The 5-year relapse-free survival rate was higher for regimen B (88.9%) than for regimen A (78.6%) and regimen C (77.2%) (P = 0.010). Stratified analysis revealed better results with the FT-combined therapy in patients positive for lymph node metastasis and premenopausal patients. These results indicate the effectiveness of using FT in combination with TAM. Of the 376 ER- patients registered, 364 were evaluated. The 5-year overall and relapse-free survival rate for ER- patients did not differ significantly between patients who received regimen D and those who received regimen E.

Isolation and characterization of primitive hematopoietic progenitors of murine fetal liver

We have isolated hematopoietic progenitors from mouse fetal liver using a sequential protocol of density gradient centrifugation, panning, and cell sorting. Isolated AA4.1+Ly-6A/E+CD43++ cells with density ranging from 1.0631 to 1.0770 g/cm3 were 480- to 600-fold enriched for multipotential progenitors relative to unfractionated cells and showed 40 to 60% colony-forming efficiency. We then examined the effects of various cytokines on the colony formation from enriched fetal liver cells. Steel factor (SF), interleukin-3 (IL-3), IL-4, IL-6, IL-11, and granulocyte colony-stimulating factor (G-CSF) as single agents supported formation of significant numbers of colonies, but flt3/flk-2 ligand (FL) and IL-12 did not. When the cytokines were combined, FL, SF, IL-3, and IL-4 each synergized individually with IL-6, IL-11, IL-12, or G-CSF to support formation of various types of colonies. Next we analyzed the growth factor requirements for proliferation and differentiation of lymphohematopoietic progenitors by using the two-step methylcellulose culture assay we established recently. None of the early-acting factors were effective as a single agent, but combinations of SF or FL with IL-6, IL-11, or G-CSF were effective in supporting B cell potential of the primary colonies. Of these, the combination of FL plus IL-11 appeared to be the most effective.

Establishment of a hepatocyte cell line producing growth-promoting factors for liver-colonizing tumor cells

A hepatocyte-derived cell line designated MLE-15A2 was established from a primary culture of mouse hepatocytes. The MLE-15A2 cells appeared to retain the basic nature of hepatocytes in that they showed morphology of an epithelial cell type and secreted albumin into the culture medium. These cells were grown on collagen-coated plates and could be easily expanded to a large-scale culture. Therefore, MLE-15A2 cells may provide a more useful model for studying liver microenvironments than primary cultures of hepatocytes. We found that conditioned media from MLE-15A2 cells, as well as from primary cultures of hepatocytes, promoted the proliferation of highly liver-colonizing colon 26 NL-17 cells better than the poorly liver-colonizing colon 26 NL-4 cells. Moreover, the conditioned media stimulated the growth of some human colon cancer cell lines. These results indicate that MLE-15A2 cells secrete growth factors that selectively stimulate certain tumor cell types. Hepatocyte-derived growth factors may regulate selective survival and colonization of tumor cells in the process of liver metastasis. The growth-promoting activity was unaffected by dialysis, was stable at 80 degrees C for 30 minutes and was bound to a heparin-Sepharose column. The major activity was eluted from the column with 0.7-0.75 M NaCl, and some minor activities eluted with lower concentrations of NaCl. These results suggest that the active components are heterogeneous heparin-binding proteins with lower affinity to heparin than platelet-derived and fibroblast growth factors.

Compartment analysis of cerebral glucose metabolism and in vitro glucose-metabolizing enzyme activities in the rat brain

To clarify the relationship between cerebral glucose metabolic rate constants and glucose-metabolizing enzyme activities in the cerebral cortex, we evaluated the cerebral metabolic rate of glucose (CMRGlu), metabolic rate constants of [18F]-2-fluoro-2-deoxy-D-glucose (FDG) and related enzyme activities in the frontal cortex under normal and glucose metabolism-suppressed conditions. Applying a three-compartment four-parameter model, metabolic rate constants were obtained by dynamic positron emission tomography with FDG, and CMRGlu was calculated based on these rate constants. The glycolytic enzyme activities were determined by in vitro biochemical assay. Three days after ibotenic acid injection into the basal forebrain, CMRGlu was decreased in the ibotenic acid-treated frontal cortex as well as k3* (phosphorylation), while K1* (plasma to brain) showed no remarkable change. No significant reductions of the enzyme activities except for hexokinase activity were found in the frontal cortex. Regression analysis showed a significant positive correlation between k3* and the hexokinase activity. These results suggested that k3* in the compartment analysis reflects hexokinase activity.

Activation of two Cynops genes, fork head and sonic hedgehog, in animal cap explants

We have isolated cDNAs of sonic hedgehog (shh) and fork head from Cynops (Japanese newt) embryo. Their expression was investigated in relation to mesoderm induction by activin and basic fibroblast growth factor (bFGF). Different from these homologs in Xenopus, they are activated not only by activin but also by bFGF in animal cap explants, showing a difference of animal pole cells in responsiveness to bFGF between Cynops and Xenopus. We also investigated the involvement of fork head in shh activation. The expression of shh was activated in animal caps which overexpressed either of two Xenopus fork head homologs, pintallavis/XFD-1 or XFKH-1/XFD-1', indicating that fork head up-regulates the transcription of shh in Cynops embryo.

Suppression of hepatic allograft rejection in the rat by mitomycin C-treated donor splenocytes: in situ splenic distribution of donor class I major histocompatibility complex antigen-positive cells in the recipient

A single intravenous injection of 3 x 10(6) donor splenocytes treated with mitomycin C (MMC) 7 days before hepatic transplantation prolongs survival of hepatic allografts in the ACI(RT1a) to LEW(RT1(1)) rat combination. This effect is donor specific. The in situ distribution in the recipient of the donor cells administered preoperatively was investigated using intracellularly fluorescence-labeled donor splenocytes. The donor cells were accumulated mainly in the splenic white pulp and lymph nodes at 12 and 24 hr after injection. Contrarily, very few cells were seen in the thymus, liver, kidney, and lung. The number of cells with dull and weak fluorescence began to increase in the splenic white pulp and lymph nodes at 24 hr after injection. This may indicate the breakdown of donor cells by recipient cells. In contrast, a number of donor cells could be detected even after 48 hr and a few cells at 7 days after splenocyte injection in the LEW-to-LEW isogeneic combination. As we previously revealed the role of class I major histocompatibility complex (MHC) antigens in prolonging hepatic allograft survival in the rat, the splenic distribution of donor class I MHC-positive cells in the recipient after intravenous administration of MMC-treated donor splenocytes was studied using immunostaining with a MN4-91-6 mouse anti-rat RT1.Aa class I MHC monoclonal antibody. The donor class I-positive cells accumulated mainly in the splenic white pulp at 12 and 24 hr after injection. This is similar to that observed in the fluorescence study. Within 48 hr after injection, most cells had disappeared from the recipient tissue. These findings suggest that the splenic white pulp, a T-dependent area, may play an important role in inducing immunological unresponsiveness.

[Early clinical trials in ECTG. Early Clinical Trial Group]

Methodology to conduct phase I trials in the Early Clinical Trial Group (ECTG) in Europe was reviewed and compared with current status of the trials in Japan. Single dose acute toxicity studies and repeated dose toxicity studies were required in order to enter phase I trials in Europe, while in Japan those results and various other toxicity studies such as mutagenecity, carcinogenecity and reproductive toxicity were required. Since significant numbers of new anticancer drugs are dropped in the early stage of clinical investigations, it is recommended that unnecessary toxicological studies be avoided. Repeated administration and dose escalations in the same patients are allowed during phase I trials in ECTG, partly in consideration of the patient's desire to obtain antitumor effects. Dose intensity and quality of life are considered in order to decide the optimal dose and schedule in phase II trials.

Cholinergic projection from the basal forebrain and cerebral glucose metabolism in rats: a dynamic PET study

To investigate the influence of cholinergic projections from the basal forebrain on cerebral cortex metabolism, we evaluated the cerebral metabolic rate of glucose (CMRGlu) after selective inhibition of cholinergic neurons in the rat basal forebrain using the pyruvate dehydrogenase complex inhibitor 3-bromopyruvic acid (BPA), and compared the results with those obtained after lesioning the basal forebrain with ibotenic acid, as well as with those from a sham-operated control group. CMRGlu was measured using positron emission tomography (PET) with [18F]-2-fluoro-2-deoxy-D-glucose (FDG). Three days after surgery, CMRGlu and k3 (phosphorylation of FDG) were reduced similarly in the frontal cortex on the BPA-injected side and in the ibotenic acid-treated group, whereas K1 (transport rate of FDG from the plasma to brain) showed no marked changes. At 3 weeks postoperatively, the CMRGlu and k3 of the frontal cortex in both groups recovered to levels similar to those of the sham-operated group. The main difference between the BPA and ibotenic acid groups was that CMRGlu showed mild reduction on the side contralateral to the operation in the former, while such reduction was confined to the ipsilateral hemisphere in the latter. The present results indicate that the cholinergic system in the basal forebrain regulates cerebral cortex glucose metabolism through direct excitation of cortical neurons.

Association of tumor cell proliferation with lymph node metastasis in early gastric cancer

Recently, many studies have reported on the relationship between malignant potential of neoplasms and cell proliferation. Proliferating cell nuclear antigen (PCNA) is an auxiliary protein of DNA polymerase delta and is considered to correlate with the cell's proliferative state. In this study, we investigated the correlation between tumor cell proliferation and nodal status of early gastric carcinoma. One hundred two endoscopically biopsied specimens from patients with early gastric carcinoma prior to operation were investigated by an immunohistochemical study, using anti-PCNA monoclonal antibody. Correlation of PCNA labeling index (percentage of positive cells per over 500 tumor cells) with nodal status were studied. PCNA labeling index in patients with lymph node metastasis was significantly higher in those without metastasis. Moreover, multivariate analysis indicated that PCNA labeling index is an independent significant factor for lymph node metastasis. As a result of this study, PCNA labeling index was suggested to be effective as one of the predictors of lymph node metastasis.

The protective effects of long-acting recombinant human pancreatic secretory trypsin inhibitor (R44S-PSTI) in a rat model of cerulein-induced pancreatitis

The effects of pancreatic secretory trypsin inhibitor (PSTI) on cerulein-induced pancreatitis were studied in a rat model. Arg44 of PSTI was replaced by Ser using site-directed mutagenesis (R44S-PSTI). R44S-PSTI has a longer half-life than the natural form. Pancreatitis was induced by four intramuscular injections of cerulein (50 microgram/kg at 1 h intervals). Continuous intravenous infusion of R44S-PSTI began at a dose of 20 micrograms/kg/h 30 min before the first cerulein injection, and was completed 3 h after the last cerulein injection. Tumour necrosis factor (TNF-alpha) production by isolated peritoneal macrophages from rats with cerulein-induced pancreatitis increased following lipopolysaccharide stimulation, compared to control rats (P < 0.01). R44S-PSTI administration significantly decreased the TNF-alpha production by peritoneal macrophages from rats with cerulein-induced pancreatitis (P < 0.05). In addition, R44S-PSTI significantly reduced serum amylase activity (P < 0.01) and pancreatic wet weight after pancreatitis induction (P < 0.05). Histological examination revealed marked acinar cell vacuolization, interstitial oedema, and cellular infiltration in cerulein-induced pancreatitis, but a lesser degree of histological change in rats that were treated with R44S-PSTI. Prophylactic use of intravenous R44S-PSTI infusion may reduce the severity of acute pancreatitis either histologically or serologically.

A case of Trichuris trichiura infection diagnosed by colonoscopy

A 65-year-old Japanese female was admitted to our hospital because of right lower abdominal pain. Laboratory and roentgenological tests revealed no abnormalities. Repeated stool examinations revealed no ovum or parasite. However, colonoscopic examination demonstrated the presence of a parasite on the edematous mucosa of cecum. The adult male whipworm (Trichuris trichiura) was then removed endoscopically. Her symptoms disappeared quickly, and no additional parasite was found in the feces during or after the mebendazole treatment. Repeated stool examinations failed to show any ova, because this patient was infected by a single male parasite. Colonoscopic study should be considered a useful tool for the diagnosis of T. trichiura infection, even if no ovum is found in stool examination.

Postoperative chemotherapy for colorectal cancer by combining 5-fluorouracil infusion and 1-hexylcarbamoyl-5-fluorouracil administration after curative resection

BACKGROUND

Colorectal cancer is one of the major malignant diseases and, recently, its incidence appears to be increasing. Surgical resectability is an important prognostic determinant; however, recurrent tumors are commonly noted, even after apparently curative surgery. Because such metastatic disease cannot be cured, better adjuvant therapies are urgently called for.

METHODS

We studied the effect of postoperative chemotherapy using 5-fluorouracil (5-FU) infusions and 1-hexylcarbamoyl-5-fluorouracil (HCFU) oral administration for curatively resected Stage II to IV colorectal cancer. This study was prospectively randomized and controlled and 251 (93.3%) of 269 patients were determined to be candidates for statistical assessment. The inductive regimen for Group A included a total of 6 5-FU intravenous injections, 10 mg/kg, on postoperative days 0, 1, 2, 7, 8, and 9. For maintenance therapy, Group A also received oral HCFU, 300 mg daily for 52 weeks beginning 2 weeks after surgery. The regimen for Group B included only 5-FU injections of Group A.

RESULTS

There were no differences in the prognostic factors or doses of 5-FU between Groups A and B. In addition, no difference was observed in the toxicity rate between the two groups. Group A, with 5-FU infusions plus oral HCFU administration, produced a reduction in the recurrence rate and a prolongation of the survival time for patients with rectal cancer. In a retrospective analysis, this protocol was also effective for patients with Stage III to IV, wall invasion-positive, and lymph node metastasis-positive colorectal cancers.

CONCLUSIONS

This study suggests that the combination of 5-FU infusions and the continuous oral administration of HCFU is a reasonable therapeutic approach for patients with surgically resected colorectal cancer and a high risk of recurrence.

Functional hierarchy of c-kit and c-fms in intramarrow production of CFU-M

Whereas the molecular natures of M-CSF/CSF-1 and its receptor c-fms are well characterized, its actual role in the intramarrow hematopoiesis remains obscure. This is because disruption of this signaling pathway results in the osteopetrosis mouse that lacks the bone cavity for hematopoiesis. To elucidate the role of c-fms in intramarrow hematopoiesis, we produced an antagonistic monoclonal antibody to murine c-fms and investigated its expression and function in the normal bone marrow. c-fms+ cells were detected both in mature and immature hematopoietic cells. Morphologically, c-kit+c-fms-, c-kit+c-fms+ and c-kit-c-fms+ cells were medium sized blasts, large promyelocytes with azurophilic granules and mature monocytes respectively. CFU-M was 10-fold more enriched in the c-kit+c-fms- than c-kit+c-fms+ fraction. Moreover, injection of the anti c-fms antibody had no effect on the production of CFU-M in the bone marrow, while anti-c-kit mAb could deplete them. As c-kit+c-fms+ cells were readily generated in the culture of c-kit+c-fms- cells, most of the CFU-M in the bone marrow are, in fact, c-fms- cells that differentiate into c-fms+ upon culture. These observations indicate a clear functional hierarchy of c-kit and c-fms in the bone marrow. Namely, c-kit plays the primary role in the production and maintenance of CFU-M, while c-fms, though it co-expressed with c-kit and functions as the growth receptor for M-CSF in the culture, has only a minimum role in the proliferation of c-fms+ cells in the bone marrow.

Negative regulation of early T lymphopoiesis by interleukin-3 and interleukin-1 alpha

We recently developed a two-step clonal cell culture system for murine lymphohematopoietic progenitors that are capable of producing myeloid and B-lymphoid progenies and characterized their cytokine requirements. We subsequently observed that addition of interleukin-3 (IL-3) or IL-1 alpha to permissive cytokine combinations in primary culture abrogates the B-lymphoid potential but not the myeloid potential of the lymphohematopoietic progenitors. We now describe a similar negative regulation of the T-cell potential of the lymphohematopoietic progenitors. Lin- Ly-6A/E+ marrow cells from 5-fluorouracil-treated mice were plated individually by micromanipulation in methylcellulose culture with steel factor (SF) and IL-11 for 8 days. The resulting colonies were tested for myeloid potential by reculturing part of each colony in secondary myeloid suspension culture. Remainders of individual primary colonies were injected intravenously into scid mice for determination of T- and B-lymphoid potentials. Approximately 10% of the progenitors that differentiated along myeloid lineages in culture reconstituted T- and B-cell compartments in scid mice. However, when scid mice were injected with colonies pooled from cultures containing steel factor, IL-11, and either IL-3 or IL-1 alpha, there was no reconstitution of thymocytes or spleen T cells. These results suggest negative regulatory roles for IL-3 and IL-1 alpha in the early stages of T lymphopoiesis.