Associations of PD-L1, PD-L2, and HLA class I expression with responses to immunotherapy in patients with advanced sarcoma: post hoc analysis of a phase 1/2 trial.

BACKGROUND: Although immunotherapy is thought to be a promising cancer treatment, most patients do not respond to immunotherapy. In this post hoc analysis of a phase 1/2 study, associations of programmed death ligand 1 (PD-L1), PD-L2, and HLA class I expressions with responses to dendritic cells (DCs)-based immunotherapy were investigated in patients with advanced sarcoma. METHODS: This study enrolled 35 patients with metastatic and/or recurrent sarcomas who underwent DC-based immunotherapy. The associations of PD-L1, PD-L2, and HLA class I expressions in tumor specimens, which were resected before immunotherapy, with immune responses (increases of IFN-γ and IL-12) and oncological outcomes were evaluated. RESULTS: Patients who were PD-L2 (+) showed lower increases of IFN-γ and IL-12 after DC-based immunotherapy than patients who were PD-L2 (-). The disease control (partial response or stable disease) rates of patients who were PD-L1 (+) and PD-L1 (-) were 0% and 22%, respectively. Disease control rates of patients who were PD-L2 (+) and PD-L2 (-) were 13% and 22%, respectively. Patients who were PD-L1 (+) tumors had significantly poorer overall survival compared with patients who were PD-L1 (-). No associations of HLA class I expression with the immune response or oncological outcomes were observed. CONCLUSIONS: This study suggests that PD-L1 and PD-L2 are promising biomarkers of DC-based immunotherapy, and that addition of immune checkpoint inhibitors to DC-based immunotherapy may improve the outcomes of DC-based immunotherapy.

Color-coding cancer and stromal cells with genetic reporters in a patient-derived orthotopic xenograft (PDOX) model of pancreatic cancer enhances fluorescence-guided surgery.

Precise fluorescence-guided surgery (FGS) for pancreatic cancer has the potential to greatly improve the outcome in this recalcitrant disease. To achieve this goal, we have used genetic reporters to color code cancer and stroma cells in a patient-derived orthotopic xenograft (PDOX) model. The telomerase-dependent green fluorescent protein (GFP)-containing adenovirus OBP-401 was used to label the cancer cells of a pancreatic cancer PDOX. The PDOX was previously grown in a red fluorescent protein (RFP) transgenic mouse that stably labeled the PDOX stroma cells bright red. The color-coded PDOX model enabled FGS to completely resect the pancreatic tumors including stroma. Dual-colored FGS significantly prevented local recurrence, which bright-light surgery or single-color FGS could not. FGS, with color-coded cancer and stroma cells has important potential for improving the outcome of recalcitrant-cancer surgery.

Indoleamine 2,3-dioxygenase in the pathogenesis of tuberculous pleurisy.

BACKGROUND: Pleural fluid is a frequent manifestation in pulmonary diseases, such as lung cancer and infectious diseases, including pulmonary tuberculosis (TB). The enzyme indoleamine 2,3-dioxygenase (IDO) catalyses tryptophan through the kynurenine pathway, and is considered a crucial immunoregulatory molecule mediating immune tolerance. Recent studies have shown IDO activity to be a novel prognostic factor not only in cancer patients but also in those with infectious diseases, including pneumonia and pulmonary TB. However, no studies have measured and determined the clinical significance of IDO activity in pleural fluid. METHODS: We enrolled 92 patients, including 34 with tuberculous pleurisy (TBP), 36 with malignant pleuritis and 15 with parapneumonic effusions. IDO activity was evaluated using liquid chromatography/electrospray ionisation tandem mass spectrometry, and was estimated by calculating kynurenine-to-tryptophan ratio. RESULTS: Pleural fluid from patients with TBP had significantly higher kynurenine concentrations and significantly lower tryptophan concentrations, resulting in significantly higher IDO activity compared with pleural effusion or serum from non-tuberculous pleuritis (all P < 0.001). Pleural tissue from TBP showed enhanced IDO expression in epithelioid granuloma regions by immunohistochemistry. CONCLUSIONS: These results suggest that IDO is strongly involved in the pathogenesis of TBP.

Impact of recipient statin treatment on graft-versus-host disease after allogeneic hematopoietic cell transplantation.

We retrospectively analyzed outcomes among 1206 patients with hematologic malignancies who had hematopoietic cell transplantation (HCT) from HLA-identical siblings (n = 630) or HLA-matched unrelated donors (n = 576) at a single institution between 2001 and 2007 for a correlation between recipient statin use and risk of graft-versus-host disease (GVHD). Among recipients with cyclosporine-based postgrafting immunosuppression (n = 821), statin use at the time of transplant (6%) was associated with a decreased risk of extensive chronic GVHD (cGVHD) (multivariate hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.4-1.0; P = .05) and an increased risk of recurrent malignancy (HR, 1.75; 95% CI, 1.0-3.0; P = .04). Recipient statin use, however, had no apparent impact on the risks of cGVHD and recurrent malignancy among recipients given tacrolimus-based immunosuppression (n = 385; 8% statin treated). Risks of acute GVHD, nonrelapse mortality, and overall mortality were not significantly affected by recipient statin use. Hence, recipient statin treatment at the time of allogeneic HCT may decrease the risk of cGVHD in patients with cyclosporine-based immunosuppression, but at the expense of a compromised graft-versus-tumor effect.

Disease recurrence patterns after R0 resection of hilar cholangiocarcinoma.

BACKGROUND: There is little information regarding the clinical behaviour of hilar cholangiocarcinoma after curative resection. METHODS: A retrospective study was undertaken of 79 consecutive patients with hilar cholangiocarcinoma who had undergone major hepatectomy (three or more Couinaud segments) concomitant with caudate lobectomy, and had negative resection margins. Sites of initial disease recurrence were classified as locoregional (porta hepatis) or distant (intrahepatic, peritoneal, para-aortic lymph nodal or extra-abdominal). Univariable and multivariable analyses were performed to determine the factors potentially related to recurrence. RESULTS: Disease recurrence was observed in 42 (53 per cent) of the 79 patients. Cumulative recurrence rates at 3 and 4 years after surgery were 52 and 56 per cent respectively. Locoregional recurrence alone was observed in eight (10 per cent) and distant metastasis in 34 (43 per cent) of the 79 patients after R0 resection. Positive nodal involvement and high International Union Against Cancer tumour (T) stage were independent prognostic factors associated with distant metastasis. CONCLUSION: Distant metastases are more common than locoregional recurrence after R0 resection for hilar cholangiocarcinoma, and associated with nodal involvement and high T stage.

Arterial reconstruction in a case of subintimal dissection of celiac arterial tributaries in living donor liver transplantation: a case report.

BACKGROUND: Hepatic arterial reconstruction is one of the critical issues in living donor liver transplantation (LDLT). Herein we have reported an LDLT case whose celiac arterial trunk tributaries were insufficient as host arteries because of extensive subintimal dissection proceeding to all tributaries of the celiac arterial trunk. PATIENTS AND METHODS: A 45-year-old woman with fulminant hepatic failure underwent LDLT. After reperfusion of the hepatic and portal veins, subintimal dissection of the recipient right and left hepatic arteries was found to extend to all tributaries of the celiac arterial trunk, preventing an anastomosis using the more proximal part of these arteries. Therefore, a jejunal arterial arcade of Roux-en-Y limb mobilized for biliary reconstruction was anastomosed to the donor left hepatic artery in end-to-end fashion. RESULTS: Arterial blood flow to the grafted liver was established successfully, and the patient's postoperative recovery was excellent. Postoperative computed tomography demonstrated sufficient hepatic arterial blood flow. The patient is doing well 4 years after transplantation. CONCLUSION: The method of hepatic graft arterialization described herein is an important option for LDLT recipients when tributaries of the celiac arterial trunk are insufficient as host arteries.

Upregulated EMMPRIN/CD147 might contribute to growth and angiogenesis of gastric carcinoma: a good marker for local invasion and prognosis.

Tumour growth depends on angiogenesis, which is closely associated with vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). Extracellular MMP inducer (EMMPRIN) was reported to involve in the progression of malignancies by regulating expression of VEGF and MMPs in stromal cells. To clarify the role of EMMPRIN in progression and angiogenesis of gastric carcinoma, expression of EMMPRIN, ki-67, MMP-2, MMP-9 and VEGF was examined on tissue microarray containing gastric carcinomas (n=234) and non-cancerous mucosa adjacent to carcinoma (n=85) by immunohistochemistry. Additionally, microvessel density (MVD) was assessed after labelling with anti-CD34 antibody. Extracellular MMP inducer expression was compared with clinicopathological parameters of tumours, including levels of ki-67, MMP-2, MMP-9 and vascular endothelial growth factor (VEGF), MVD as well as survival time of carcinoma patients. Gastric carcinoma cell lines (HGC-27, MKN28 and MKN45) were studied for EMMPRIN expression by immunohistochemistry and Western blot. Extracellular MMP inducer expression was gradually increased from normal mucosa to carcinomas through hyperplastic or metaplastic mucosa of the stomach (P<0.05). There was strong EMMPRIN expression in all gastric carcinoma cell lines despite different levels of glycosylation. Extracellular MMP inducer expression was positively correlated with tumour size, depth of invasion, lymphatic invasion, expression of ki-67, MMP-2, MMP-9 and VEGF of tumours (P<0.05), but not with lymph node metastasis, UICC staging or differentiation (P>0.05). Interestingly, there was a significantly positive relationship between EMMPRIN expression and MVD in gastric carcinomas (P<0.05). Survival analysis indicated EMMPRIN expression to be negatively linked to favourable prognosis (P<0.05), but not be independent factor for prognosis (P>0.05). Further analysis showed three independent prognostic factors, depth of invasion, lymphatic and venous invasion, to influence the relationship between EMMPRIN expression and prognosis. Upregulated expression of EMMPRIN possibly contributes to genesis, growth and local invasion of gastric carcinomas. Altered EMMPRIN expression might enhance growth, invasion and angiogenesis of gastric carcinoma via upregulating MMP expression of both stromal fibroblasts and gastric cancer cells and could be considered as an objective and effective marker to predict invasion and prognosis.

[Isolated coronary artery bypass grafting in octogenarians].

We evaluate the outcomes of isolated coronary artery bypass grafting (CABG) in high-risk octogenarians. There are 20 cases in 5 years, which contain 1 re-operation case, and 10 emergency cases. Nineteen cases were performed off-pump CABG (OPCAB), and conventional CABG was performed for only 1 case because of unstable hemodynamics with intraaortic balloon pumping (IABP). We generally performed CABG with aorta no-touch technique. There is no death case, and no serious complication like stroke. We used 23 artery and 11 vein grafts for CABG, and mean number of grafts per patient was 1.8+/-0.7. And "hybrid therapy" with percutaneous transluminal coronary angioplasty (PTCA) was done for 5 cases. Octogenarians are at increased risk for perioperative morbidity and mortality after CABG, but we have performed OPCAB for them and have had good results. And we think that aorta no-touch technique, proper selection and use of graft are important.

Transitional cell carcinoma of the renal pelvis in a long-term hemodialysis patient with autosomal dominant polycystic kidney.

We present a case of renal pelvic transitional cell carcinoma (TCC) accompanied by autosomal dominant polycystic kidney disease (ADPKD). An 81-year-old woman on long-term hemodialysis for ADPKD visited the Department of Urology at Kouseiren Takaoko Hospital, complaining of asymptomatic macroscopic hematuria. Retrograde pyelogram showed an irregular filling defect in the right renal pelvis, which suggested the right renal pelvic tumor. We performed right nephrectomy and transurethral removal of the right ureter. Histological diagnosis demonstrated renal pelvic TCC.

A rat model of dilated cardiomyopathy to investigate partial left ventriculectomy.

BACKGROUND: This study is the first to assess a small animal model of dilated cardiomyopathy (DCM) for evaluation of partial left ventriculectomy. METHOD: Eighteen Dahl salt-sensitive (DS) rats were divided into three groups. Six rats were fed an 8% high-salt diet from the age of 7 weeks (Group 1), and similarly six rats from 8 weeks (Group 2) and six from 9 weeks (Group 3). Blood pressure (BP) was measured by the tail-cuff method and left ventricular (LV) dimensions by echocardiography. RESULTS: In Groups 1 and 2, systolic BP rose and reached 200 mmHg by the 10th to 11th week, when all rats died within a week without signs of heart failure. However, in Group 3, systolic BP gradually rose to 196+/-15 mmHg (mean +/- SD) at the age of 14 weeks, when LV end-diastolic diameter (EDD) was 6.2+/-0.4 mm (control 5.1+/-0.7 mm) and LV fractional shortening (FS) was 77+/-3% (control 68+/-3%). At the age of 25 to 30 weeks, all rats in Group 3 showed signs of congestive heart failure, systolic BP remained high, EDD markedly increased (8.7+/-0.6 mm), and LVFS decreased (38.9+/-8.1%). From this stage, rats survived for 13.7+/-5.9 days. We employed the Group 3 model for our pilot PLV study. Eight rats had PLV with a beating heart by plicating the LV area between the papillary muscle bases. Two rats died perioperatively but the rest survived (60% survival 3 weeks after PLV). Postoperatively, the rats' LVEDD decreased and FS improved significantly. CONCLUSIONS: Using DS rats, we developed a DCM model for investigating PLV. The model may contribute to scientific investigation of PLV.

Multi-layer amniotic membrane graft for pterygium in a patient with xeroderma pigmentosum.

BACKGROUND: Xeroderma pigmentosum (XP) is a rare, autosomal recessive, premalignant condition of the skin, and is reported to be associated with ocular surface disorders such as conjunctival malignancy and pterygium. Herein, we report a case of successful management of pterygium with multi-layer amniotic membrane graft (AMG) in a young XP patient. CASE: An 11-year-old Japanese girl, who had been diagnosed as having XP, was referred to us for treatment of her bilateral pterygium. Surgical intervention was attempted for a temporal, presumably fast-growing pterygium in her left eye. Multi-layer amniotic membrane grafting was performed. OBSERVATIONS: The surgery-induced pain and irritation disappeared within a day. The limbal conjunctival autograft survived on the AMG and re-epithelialization over the AMG was completed in 2 weeks. Best corrected visual acuity improved from 20/32 to 20/16 one month postoperatively. During the 1-year follow-up period, no recurrence was noted. CONCLUSIONS: The present case exemplifies that AMG as an adjunct to primary pterygium resection is effective even in a young patient with XP. In addition, multi-layer AMG, which we first demonstrated in this report, seems to be useful for protecting bare sclera and extraocular muscles from mechanical injury.

Initial effects of the left ventricular repair by plication may not last long in a rat ischemic cardiomyopathy model.

BACKGROUND: Long term effects of left ventricle (LV) repair surgery (LVR) for ischemic cardiomyopathy are not well understood. METHODS AND RESULTS: Sixty-nine rats developed ischemic cardiomyopathy with large akinetic LV area 4 weeks after the left anterior descending artery was ligated. In a second surgery 4 weeks later, 33 rats underwent LVR by plication of the akinetic LV area (LVR group), and 36 underwent rethoracotomy alone (sham group). No medication was used in either group. All rats survived the second surgery. LV end-diastolic dimension as measured by echocardiography, LV fractional shortening, and the maximal end-systolic pressure-volume relationship (E(max)) as calculated from the data by catheter-tipped manometer and echocardiography improved in the LVR group after the second surgery, but LV end-diastolic dimension and E(max) gradually deteriorated as time passed. LV end-diastolic pressure improved 1 week after LVR but rose significantly 4 weeks after LVR. Brain natriuretic peptide mRNA was lower in the LVR group than in the sham group 1 week after LVR but not 4 weeks postoperatively. CONCLUSIONS: Initial improvement in LV function and neurohormonal status after LVR did not last for 4 weeks in this rat model when untreated medically. The mechanism of deterioration should be elucidated to improve long-term results of LVR.

Value of lipiodol computed tomography and digital subtraction angiography in the era of helical biphasic computed tomography as preoperative assessment of hepatocellular carcinoma.

OBJECTIVE: To compare the diagnostic accuracies of Lipiodol computed tomography (CT) and helical biphasic CT as preoperative imaging modalities for hepatocellular carcinoma (HCC). SUMMARY BACKGROUND DATA: Lipiodol CT after digital subtraction angiography has long been used as a highly sensitive imaging modality for HCC. The recent advent of helical CT has allowed scanning the entire liver during both the arterial and portal venous phase of contrast enhancement. METHODS: The authors analyzed data from 164 patients who underwent hepatic resection for HCC to calculate the sensitivity and specificity of these modalities. Findings of intraoperative ultrasonography followed by histologic confirmation were set as the gold standard. RESULTS: Although sensitivity decreased with both modalities as tumors became small and well differentiated, helical CT showed a higher sensitivity than Lipiodol CT in detecting well-differentiated HCC nodules smaller than 2 cm. In contrast, Lipiodol CT was superior to helical CT for the detection of small but moderately to poorly differentiated nodules. The overall sensitivity of helical CT was higher than that of Lipiodol CT. These findings suggest that helical CT is superior in delineating early HCC, whereas Lipiodol CT is specific to the detection of intrahepatic metastases. In terms of specificity, helical CT was superior to Lipiodol CT. CONCLUSIONS: Helical CT and Lipiodol CT are complementary modalities. At present, helical biphasic CT does not obviate the need for invasive techniques such as angiography and Lipiodol CT as preoperative examinations for HCC.

Identification of hepatic venous territories in liver resection by using color Doppler ultrasonography: report of two cases.

OBJECTIVE: Resection of the hepatic vein because of the proximity of tumors may result in increased congestion in the noncancerous parenchyma, which in turn may lead to functional hepatic volume loss and postoperative hepatic failure, especially in a case of low hepatic reserve. However, to our knowledge, no technique for estimating the extent of dependent hepatic venous territories before hepatic resection has been established. We examined the possibility of using color Doppler ultrasonography for this purpose. METHODS: A color Doppler system and a linear array transducer equipped with multiple Doppler frequencies ranging from 7 to 13 MHz were used intraoperatively. Two patients with hepatocellular carcinomas were examined. By tracking entire branches of the targeted vessel, from the trunk to the terminal branches extending to the liver surface, it was possible for the boundaries of the dependent areas to be projected and marked on the liver surface with either ink or electrocautery. RESULTS: In both cases, this method was effective for either minimizing the congestive area or preserving the hepatic mass that was being drained via aberrant routes. CONCLUSIONS: Identification of hepatic venous territories by means of color Doppler ultrasonography may provide new information about intrahepatic blood circulation and may increase the safety and curability of hepatic resection.

[Clinicopathological study of the testicular microlithiasis].

PURPOSE: Testicular microlithiasis (TM) is a relatively rare condition characterized by calcific concref1p4 within the seminiferous tubules. Little has been reported on the incidence or the clinical implication of TM among Japanese. To address the problem, we evaluated pathologic specimens from biopsies and orchiectomies, of testes with various conditions. MATERIALS AND METHODS: Pathologic specimens of the testes of 200 cases, 56 from orchiectomy and 144 from testicular biopsy, were investigated. RESULTS: The pathological diagnosis of TM was confirmed in seven (3.5%) cases, four of which were associated with germ cell tumors and the other three were obtained from testicular biopsies performed for examination of infertile men. Of the 41 patients with germ cell tumors, four (9.8%) were found to have TM, and another three (2.5%) were identified among 122 patients with infertility. The prevalence of TM is significantly higher in specimen with germ cell tumors than those without germ cell tumors (p < 0.05). CONCLUSIONS: Although TM is rarely encountered, this condition is relatively often accompanied by testicular malignancy. Further investigation would be fundamental to ascertain the relationship between TM and testicular malignancy.

[Torsion of the spermatic cord in undescended testis: report of two cases].

We report two cases of torsion of the spermatic cord in undescended testis. Case 1: A 23-year-old man was admitted to our hospital with the complaints of fever and left inguinal pain. He had cerebral palsy in his past history. Tentative diagnosis of acute epididymitis of left undescended testis was made, and antibacterial drugs were given. Response was poor, and torsion of the spermatic cord was suspected strongly. Torsion of the spermatic cord in undescended testis and severe testicular infarction were seen in surgery after 13-day conservative treatment. Orchiectomy was performed. Case 2: A 6-year-old boy was admitted to our hospital with the chief complaints of left inguinal mass and pain. He had felt abdominal pain for 3 days. Scrotal contents were impalpable and the diagnosis of torsion of the spermatic cord was made. Orchiectomy was performed due to severe testicular infarction.

Sonographic detection of visceral adhesion in percutaneous drainage of afferent-loop small-intestine obstruction.

To facilitate the percutaneous drainage of an afferent-loop small-intestine obstruction, we used sonography to detect visceral adhesions and select a safe puncture route. The portion of the small intestine that was fixed to the anterior abdominal wall was sonographically identified by using a high-frequency transducer to locate the area of restricted visceral sliding. The needle was then inserted into the intestine. In 3 cases, we have found that this technique improves the confidence of the physicians who perform the percutaneous drainage and may help to minimize the risks associated with the percutaneous drainage.

Erythrocyte enzyme activities in cord blood of extremely low-birth-weight infants.

To investigate the features of erythrocyte metabolism in extremely immature infants, we assayed 21 enzyme activities and glutathione level in cord erythrocytes from 28 extremely low-birth-weight infants (ELBWI; defined as birth weight <1,000 g). The results were compared with those from normal adults and non-neonatal reticulocyte-rich controls. Statistical analysis revealed that activities of six enzymes (glucosephosphate isomerase, phosphoglycerate kinase, monophosphoglycerate mutase, enolase, glucose-6-phosphate dehydrogenase (G6PD), and glutathione reductase) were significantly higher, and those of eight other enzymes (phosphofructokinase, 6-phosphogluconate dehydrogenase (6PGD), glutathione peroxidase, adenylate kinase, adenosine deaminase, acetylcholinesterase, NADH methemoglobin reductase, and catalase) were lower in ELBWI taking their marked reticulocytosis into consideration. The 6PGD/G6PD ratio, which is consistently unchanged under various physiological and pathological conditions, was markedly reduced in ELBWI. Our results support the previous reports that neonatal erythrocytes have a unique metabolic pattern which is different from that of adult erythrocytes, and also suggest that the 6PGD/G6PD ratio might be an index for the developmental immaturity of fetal erythrocytes. This is the first report describing the pattern of erythrocyte enzyme activities in ELBWI.

Evaluation of the blue formazan spot test for screening glucose 6 phosphate dehydrogenase deficiency.

Several screening tests for glucose 6 phosphate dehydrogenase (G6PD) deficiency have been reported thus far, and a standardized method of testing was proposed by the International Council for Standardization in Hematology (ICSH). The screening test used in any particular laboratory depends upon a number of factors such as cost, time required, temperature, humidity, and availability of reagents. In this study, a direct comparison between three different G6PD screening methods has been undertaken. In 71 cases (50 hematologically normal volunteers, 9 hemizygous G6PD-deficient males, and 12 heterozygous deficient females), the blue formazan spot test (BFST) was compared with the conventional methemoglobin reduction test (HiRT) and the ICSH-recommended fluorescent spot test (FST-ICSH). In all cases, the results obtained with the three screening tests were correlated with the enzyme activity assayed spectrophotometrically. In hemizygous G6PD-deficient males, all cases were equally detected with the three methods: BFST (4.7-6.64, controls: 11.1-13.4), BMRT (score +3 in all 9 cases), and FST (no fluorescence in 9 cases). In heterozygous G6PD-deficient females, two methods detected 7 out of 12 cases (BFST: 8.71-11.75, controls: 11.1-13.4; and BMRT: score +3 in 7 cases), whereas the FST-ICSH missed all 12 cases that presented a variable degree of fluorescence. Although the sensitivity for G6PD-deficient carrier detection is the same for the BMRT and the BFST, the latter has the advantage of being semiquantitative and not merely qualitative. Unfortunately, none of the three screening tests compared here allowed the detection of the 100% heterozygote carrier state of G6PD deficiency.

Apoptotic changes precede mitochondrial dysfunction in red cell-type pyruvate kinase mutant mouse erythroleukemia cell lines.

Two erythroleukemia cell lines have been established from the splenic lesions of red blood cell-type pyruvate kinase (R-PK) activity-deficient mice of CBA/N origin infected with a polycythemic strain of Friend leukemia virus complex (FVp). Ten to 30% of the cells of these cell lines undergo apoptotic changes in routine passage, as shown by nuclear fragmentation, DNA laddering, DNA content (propidium iodide (PI) staining), and annexin V binding assay. In these cells, however, although adenosine 5'-triphosphate (ATP) levels were lower than in the control cells, the mitochondrial inner transmembrane potential (delta psi m), detected by rhodamine 123 (R123) and diSC3(5) staining, remained unchanged until the final stage of apoptosis. No evidence was obtained to relate this finding to R-PK mutation due to difficulty in cloning stable, conditionally inducible R-PK gene transfectants. However, low delta psi m in the apoptotic cell population of the control T3-K-1 (K-1) and T3-CI-2-0 (2-0) Friend erythroleukemia cells supports a possible relationship, as do results obtained in two Friend erythroleukemia cells recently isolated from normal CBA/N mice. These cell lines are expected to be useful for clarifying both the primary apoptotic changes independent of mitochondrial dysfunction and the PK-isozyme changes during erythrodifferentiation, for example, the decreased muscle type 2 (M2) PK level. Modification of growth signals in these cell lines may modulate differentiation and/or apoptosis and allow further elucidation of the signaling networks.