High dose chemotherapy followed by autologous stem cell transplantation for relapsed or refractory Hodgkin’s lymphoma

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Background: High dose chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) can produce long-term durable remissions in patients (PTS) with relapsed or refractory Hodgkin’s lymphoma (HL). We investigated whether previously reported prognostic factors could predict overall survival (OS) and progression free survival (PFS) in a modern cohort of PTS, and attempted to identify any subgroup with a particularly inferior survival. Methods: A retrospective chart review was performed on all PTS with relapsed or refractory HL who received HDT and ASCT at a single institution. Results: From 1990 to 2001, 115 PTS received HDT followed by ASCT for relapsed or refractory HL. 76/109 PTS (70%) had achieved a complete response to initial therapy. Median time from initial therapy to relapse (TTR) was 18 months (range, 0–220 months). 105 PTS (91%) received HDT with cyclophosphamide, BCNU, and VP-16. The source of stem cells was bone marrow in 68 PTS (59%) and peripheral blood in 47 PTS (41%). Five year PFS and OS were 46% and 58%, respectively, with a median follow-up of 58 months (range, 1–175 months). The five year PFS and OS of the 13 PTS (11%) with primary refractory disease was 39% and 54%, respectively, not significantly different. 59 PTS (51%) died after HDT and ASCT. The most common cause of death was relapsed HL. Regimen related mortality accounted for 8 deaths (7%). Male gender and TTR <12 months were associated with decreased OS by univariate analysis (P = 0.04 and P = 0.03, respectively). Similar, but non-significant trends were noted in PFS. In multivariate analysis, only TTR <12 months was associated with a statistically significant decrease in OS (P = 0.04). Five year OS for patients with TTR <12 and ≥12 months was 44% and 63%, respectively. Second malignancies occurred in 9 PTS (8%). The most common diagnosis was myelodysplastic syndrome/acute myelogenous leukemia [n = 6 (67%)]. Conclusions: We have confirmed that HDT and ASCT produces long-term PFS and OS in a proportion of PTS with relapsed or refractory HL. TTR <12 months was associated with a statistically significant decrease in OS by multivariate analysis; however, no group of PTS, including those with primary refractory disease, could be identified who did not benefit from HDT and ASCT.

No significant financial relationships to disclose.

Tenocyte response to cyclical strain and transforming growth factor beta is dependent upon age and site of origin

The effect of strain and transforming growth factor beta on equine tendon fibroblasts (tenocytes) was assessed in vitro. Tenocytes were isolated from flexor and extensor tendons of horses from foetal to 10 years of age. These cells were cultured until confluent on collagen-coated silicone dishes. Cyclic biaxial strain of 9+/-1% was applied at 0.5 Hz for 24 hours with or without added TGFbeta1 or 3 (10 ng/ml). Proliferation and synthetic responses were dependent on the tendon of origin. Neither strain nor TGFbeta caused flexor tenocytes to proliferate significantly, while strain alone did proliferate extensor tenocytes. TGFbeta, with or without strain, increased the incorporation of [3H]-proline and the production of types I and III collagen and COMP in both cell types, although the effect on COMP production was more marked in flexor tenocytes, perhaps reflecting the higher levels found in this tendon in vivo. Immature flexor tenocytes synthesised more collagen and COMP than those from mature animals, while age had little effect in extensor tenocytes. Our results suggest that tenocytes become differentiated at an early age and present tendon-specific responses.

Valacyclovir for the prevention of cytomegalovirus infection after allogeneic stem cell transplantation: a single institution retrospective cohort analysis

A retrospective single center study was performed to evaluate the safety and efficacy of valacyclovir for prevention of cytomegalovirus (CMV) infection (reactivation) after allogeneic stem cell transplantation (SCT). We compared a group of 31 patients at risk for CMV reactivation (donor, recipient or both seropositive for CMV) who received valacyclovir at an oral dose of 1 g three times a day for CMV prophylaxis with a matched cohort of 31 patients who did not receive the drug or any other form of CMV prophylaxis. Valacyclovir was used as primary prophylaxis in 12 patients and as secondary prophylaxis (after a prior CMV reactivation was effectively treated with either ganciclovir or foscarnet and without CMV antigenemia at the start of valacyclovir) in the remaining 19 patients. The two treatment groups were well matched for the donor-recipient CMV serological status and other pre-transplant characteristics. CMV reactivation was detected by blood antigenemia testing using a commercially available immunofluorescence assay for CMV lower matrix protein pp65 in circulating leukocytes. For primary prophylaxis, 3/12 patients who received valacyclovir reactivated CMV compared to 24/31 patients in the control group (P < 0.001). For secondary prophylaxis, 5/19 valacyclovir patients reactivated compared to 16/24 control patients (P < 0.05). Valacyclovir was well tolerated except for infrequent and mild gastrointestinal side-effects. There was no difference in the incidence of CMV disease in the two groups. Prophylaxis with valacyclovir appears to be safe and efficacious in preventing both primary and secondary CMV reactivation in at-risk patients after allogeneic SCT. Larger prospective randomized studies will be required to confirm these observations.

Zinc stimulates the activity of the insulin- and nutrient-regulated protein kinase mTOR

Recent studies indicate that zinc activates p70 S6 kinase (p70(S6k)) by a mechanism involving phosphatidylinositol 3-kinase (PI 3-kinase) and Akt (protein kinase B). Here it is shown that phenanthroline, a zinc and heavy metal chelator, inhibited both amino acid- and insulin-stimulated phosphorylation of p70(S6k). Both amino acid and insulin activations of p70(S6k) involve a rapamycin-sensitive step that involves the mammalian target of rapamycin (mTOR, also known as FRAP and RAFT). However, in contrast to insulin, amino acids activate p70(S6k) by an unknown PI 3-kinase- and Akt-independent mechanism. Thus the effects of chelator on amino acid activation of p70(S6k) were surprising. For this reason, we tested the hypothesis that zinc directly regulates mTOR activity, independently of PI 3-kinase activation. In support of this, basal and amino acid stimulation of p70(S6k) phosphorylation was increased by zinc addition to the incubation media. Furthermore, the protein kinase activities of mTOR immunoprecipitated from rat brain lysates were stimulated two- to fivefold by 10-300 microM Zn2+ in the presence of an excess of either Mn2+ or Mg2+, whereas incubation with 1,10-phenanthroline had no effect. These findings indicate that Zn2+ regulates, but is not absolutely required for, mTOR protein kinase activity. Zinc also stimulated a recombinant human form of mTOR. The stimulatory effects of Zn2+ were maximal at approximately 100 microM but decreased and became inhibitory at higher physiologically irrelevant concentrations. Micromolar concentrations of other divalent cations, Ca2+, Fe2+, and Mn2+, had no effect on the protein kinase activity of mTOR in the presence of excess Mg2+. Our results and the results of others suggest that zinc acts at multiple steps in amino acid- and insulin cell-signaling pathways, including mTOR, and that the additive effects of Zn2+ on these steps may thereby promote insulin and nutritional signaling.

Outcome of allogeneic stem cell transplantation for B cell chronic lymphocytic leukemia

The objective of this study was to describe the outcome of allogeneic stem cell transplantation (alloSCT) in a series of patients with B cell chronic lymphocytic leukemia (B-CLL). Twenty-three B-CLL patients were transplanted between 1988 and 1997 using stem cells from a related (n = 20) or an unrelated donor (n = 3). The median age of the patients was 46 years, and the median number of prior chemotherapy regimens received was two. At transplantation, 14 patients had chemorefractory disease and 12 of these were refractory to fludarabine. The preparative regimens included total body irradiation (TBI) in 22 of the 23 cases. All patients received graft-versus-host disease (GVHD) prophylaxis with cyclosporine and methotrexate. Twenty patients (87%) achieved a complete remission (CR). The incidence of grade II-IV acute GVHD was 54%. Fourteen (61%) patients are alive and disease-free, including two with unrelated donors, at a median of 26 months (range, 9-115 months). Nine patients (39%) have died, one of whom had progressive B-CLL. The only favorable prognostic factor for failure-free survival (FFS) and overall survival (OS) after alloSCT was the use of a cyclophosphamide/TBI rather than an etoposide/cyclophosphamide/TBI regimen (P = 0.03). The projected 5-year FFS, OS, and relapse rates after alloSCT were 65% (95% CI, 48-88%), 62% (95% CI, 43-88%), and 5% (95%, CI 0-13%), respectively. These findings demonstrate the potential of high-dose therapy and alloSCT for inducing and maintaining a remission in patients with advanced or chemorefractory B-CLL. The low relapse rate may be due to an allogeneic graft-versus-leukemia effect.

Fluconazole vs low-dose amphotericin B for the prevention of fungal infections in patients undergoing bone marrow transplantation: a study of the North American Marrow Transplant Group

Systemic fungal infections are a major problem in bone marrow transplant recipients who have prolonged neutropenia or who receive high-dose corticosteroids. Prophylaxis with Fluconazole or low-dose amphotericin B reduces, but does not eliminate these infections. To determine which prophylactic agent is better, we performed a prospective randomized study. Patients undergoing allogeneic (related or unrelated) or autologous marrow or peripheral stem cell transplantation were randomized to receive Fluconazole (400 mg/day p. o. or i.v.) or amphotericin B (0.2 mg/kg/day i.v.) beginning 1 day prior to stem cell transplantation and continuing until recovery of neutrophils to >500/microl. Patients were removed from their study drug for drug-associated toxicity, invasive fungal infection or suspected fungal infection (defined as the presence of fever >38 degrees C without positive culture while on broad-spectrum anti-bacterial antibiotics). Proven or suspected fungal infections were treated with high-dose amphotericin B (0.5-0.7 mg/kg/day). Patients were randomized at each institution and stratified for the type of transplant. The primary end-point of the study was prevention of documented fungal infection; secondary endpoints included fungal colonization, drug toxicity, duration of hospitalization, duration of fever, duration of neutropenia, duration and total dose of high-dose amphotericin B and overall survival to hospital discharge. From July 1992 to October 1994, a total of 355 patients entered into the trial with 159 patients randomized to amphotericin B and 196 to Fluconazole. Patient groups were comparable for diagnosis, age, sex, prior antibiotic or antifungal therapy, use of corticosteroids prior to transplantation and total duration of neutropenia. Amphotericin B was significantly more toxic than Fluconazole especially in related allogeneic transplantation where 19% of patients developed toxicity vs 0% of Fluconazole recipients (p < 0.05). Approximately 44% of all patients were removed from prophylaxis for presumed fungal infection. Proven fungal infections occurred in 4.1% and 7.5% of Fluconazole and amphotericin-treated patients, respectively. Proven fungal infections occurred in 9.1% and 14.3% of related allogeneic marrow recipients receiving Fluconazole or amphotericin B, respectively, and 2.1% and 5.6% of autologous marrow recipients receiving Fluconazole or amphotericin B, respectively (P > 0.05). In this prospective trial, low-dose amphotericin B prophylaxis was as effective as Fluconazole prophylaxis, but Fluconazole was significantly better tolerated.

Oxidative stress and NF-kappaB activation: correlation in patients following allogeneic bone marrow transplantation

Although in vitro data has linked reactive oxygen species (ROS) to activation of nuclear factor kappaB (NF-kappaB), little data exist regarding this relationship in human disease. We hypothesized that bone marrow transplantation (BMT) would impart a degree of oxidative stress that might lead to in vivo activation of the redox-sensitive transcription factor NF-kappaB. Because NF-kappaB regulates transcription of many proinflammatory mediators, we reasoned that activation of NF-kappaB might contribute to the development of transplant-related complications. To evaluate NF-kappaB activation in humans, we measured NF-kappaB binding activity in nuclear extracts of bronchoalveolar lavage (BAL) cells obtained before and after allogeneic bone marrow transplantation (BMT) in 7 patients. Changes in BAL cell NF-kappaB binding activity were compared with changes in urinary F2-isoprostane concentration, an indicator of in vivo free radical-catalyzed lipid peroxidation. Although the extent of in vivo lipid peroxidation has substantial interindividual variability over time, we found a strong correlation between the pre/post-BMT ratio of urinary isoprostane concentrations and pre/post-BMT ratio of NF-kappaB binding activity in BAL cells, R = 0.96, p = 0.0005). This correlation is selective, because no relationship was found between the transcription factor CREB and urinary F2-isoprostane excretion. Although limited by the small number of patients studied, our data link oxidant stress to NF-kappaB activation in human alveolar macrophages following BMT. It is possible that such interactions may contribute to the clinical course after BMT by affecting transcription of proinflammatory genes.

Protracted results of dose-intensive therapy using cyclophosphamide, carmustine, and continuous infusion etoposide with autologous stem cell support in patients with relapse or refractory Hodgkin's disease: a phase II study from the North American Marrow Transplant Group

To determine the long-term results of high-dose chemotherapy and stem cell support in relapsed or primary refractory Hodgkin disease patients. One hundred and thirty-one patients with relapsed or primary refractory Hodgkin's disease were treated with a dose-intensive therapy protocol consisting of etoposide (2400 mg/m2 continuous intravenous infusion) cyclophosphamide (7200 mg/m2 intravenously), and carmustine (300-600 mg/m2 intravenously) CBVi. All patients had previously failed conventional chemoradiotherapy. Severe toxicities were related to infectious, hepatic, and pulmonary complications. Fatal, regimen-related toxicity was 19%; liver and lung dysfunction, as well as infection, were the most frequent problems. Ninety-one (69%) of the patients achieved a complete response (CR) (95% CI = 59% to 75%) after CBVi and autologous stem cell infusion. With a median follow-up of 5.1 years (range 3.0 to 9.5 years), overall and event-free survival are 44% (95% CI = 33% to 47%) and 38% (95% CI = 28% to 46%) respectively. While univariate analysis did not reveal a statistically significant variable to predict a better response, responsiveness to therapy demonstrated a trend. We conclude that CBVi is an effective therapy for relapsed or refractory Hodgkin's disease, producing long-term, durable remissions.

Determination of normal values using an automated coagulation timer for activated coagulation time and its application in dogs with hemophilia

The present study was performed to determine normal values for the Medtronic HemoTec automated activated coagulation time (ACT) analyzer (Medtronic HemoTec Inc, Parker, CO, distributed in Switzerland by Convergenza AG, Vaduz, Liechtenstein), and to evaluate its ability to detect dogs with hemophilia. ACT was measured in 43 healthy dogs presented to the Companion Animal Hospital, University of Bern, Bern, Switzerland, with the Medtronic HemoTec ACT analyzer to determine normal values. The mean +/- 2 standard deviations (SDs) of the values obtained was defined as the normal range. ACT was measured 8-10 times on the same day in 6 dogs to determine repeatability. ACT also was measured in 11 dogs with hemophilia and compared with a conventional visual ACT measurement test and with the activated partial thromboplastin time (APTT). ACT values of the 43 dogs used to determine normal values ranged from 66.5 to 97.0 seconds (mean, 79.3 seconds; SD, 7.35 seconds; median, 78.5 seconds). A range of 64-95 seconds (mean +/- 2 SDs) was defined as the normal range for the tested device. Repeatability was poor (r = 0.256). ACT values measured with the automated device did not correlate with ACT values measured with a conventional visual test or with APTT Sensitivity of the test was 90.9%, specificity was 98.0%, and accuracy was 96.7%. Variability in the test results was large and may lead to incorrect results. The automated measurement device was not superior to the conventional visual method in evaluating dogs with hemophilia.

BMP1-related metalloproteinases promote the development of ventral mesoderm in early Xenopus embryos

Bone morphogenetic protein 1 (BMP1) is a metalloproteinase closely related to Drosophila Tolloid (Tld). Tld regulates dorsoventral patterning in early Drosophila embryos by enhancing the activity of Dpp, a member of the TGF-beta family most closely related to BMP2 and BMP4. In Xenopus BMP4 appears to play an essential role in dorsoventral patterning, promoting the development of ventral fates during gastrula stages. To determine if BMP1 has a role in regulating the activity of BMP4, we have isolated cDNAs for Xenopus BMP1 and a novel closely related gene that we have called xolloid (xld). Whereas xbmp1 is uniformly expressed at all stages tested, the initial uniform expression of xld becomes localized to two posterior ectodermal patches flanking the neural plate and later to the inner ectoderm of the developing tailbud. xld is also expressed in dorsal regions of the brain during tailbud stages and is especially abundant in the ventricular layer of the dorsal hindbrain caudal to the otic vesicle. Overexpression of either gene inhibits the development of dorsoanterior structures in whole embryos and ventralizes activin-induced dorsal mesoderm in animal caps. Since ventralization of activin-induced animal caps can be blocked by coinjecting a dominant-inhibitory receptor for BMP2 and BMP4, we suggest a role for BMP1 and Xld in regulating the ventralizing activity of these molecules.

Donor leukocyte infusions in 140 patients with relapsed malignancy after allogeneic bone marrow transplantation

PURPOSE

Recipients of allogeneic bone marrow transplants (BMTs) who have relapsed may attain complete remissions when treated with transfusions of leukocytes obtained from the original bone marrow donor. We performed a retrospective study to characterize better this new treatment modality.

PATIENTS AND METHODS

We surveyed 25 North American BMT programs regarding their use of donor leukocyte infusions (DLI). Detailed forms were used to gather data regarding the original BMT, relapse, DLI, response to DLI, complications of DLI, and long-term follow-up evaluation. Reports of 140 patients were thus available for analysis.

RESULTS

Complete responses were observed in 60% (95% confidence interval [CI], 51.9% to 68.1%) of chronic myelogenous leukemia (CML) patients who received DLI and did not receive pre-DLI chemotherapy; response rates were higher in patients with cytogenetic and chronic-phase relapse (75.7%; 95% CI, 68.2% to 83.2%) than in patients with accelerated-phase (33.3%; 95% CI, 19.7% to 46.9%) or blastic-phase (16.7%; 95% CI, 1.9% to 31.9%) relapse. The actuarial probability of remaining in complete remission at 2 years was 89.6%. Complete remission rates in acute myelogenous leukemia (AML) (n = 39) and acute lymphocytic leukemia (ALL) (n = 11) patients who had not received pre-DLI chemotherapy were 15.4% (95% CI, 9.6% to 21.2%) and 18.2% (95% CI, 6.6% to 29.8%), respectively. Complete remissions were also observed in two of four assessable myeloma patients and two of five assessable myelodysplasia patients. Complications of DLI included acute graft-versus-host disease (GVHD) (60%; 95% CI, 51.4% to 68.6%), chronic GVHD (60.7%; 95% CI, 50.3% to 71.1%), and pancytopenia (18.6%; 95% CI, 12.2% to 25.0%). Pre-DLI characteristics predictive of complete response in CML patients were post-BMT chronic GVHD, pre-DLI disease status of chronic phase, and time interval between BMT to DLI less than 2 years. Acute and chronic GVHD post-DLI were highly correlated with disease response (P < .00001).

CONCLUSION

DLI results in complete remissions in a high percentage of patients with relapsed chronic-phase CML. Complete remissions are observed less frequently in patients with advanced CML and acute leukemia. GVHD and pancytopenia occur commonly; GVHD is highly correlated with response.

Nocardial infections in bone marrow transplant recipients

Infections caused by Nocardia species have been infrequently described in bone marrow transplant (BMT) recipients. We reviewed six cases of nocardiosis occurring in our population of BMT recipients and the four cases previously reported in the literature. The rate of nocardial infection at our institution was 0.2% (1 of 554) among autologous BMT recipients and 1.7% (5 of 302) among allogeneic BMT recipients (odds ratio, 9.3 [95% confidence interval, 1.1-80.1]; P = .046). All 10 patients had received immunosuppressive medications, and all but one allogeneic BMT recipient had acute or chronic graft-vs.-host disease (GVHD). Four patients had extensive exposure to soil or dust before nocardiosis developed. Seventy percent of the patients died, but death was less often due to progressive nocardial infection than to complications of GVHD and associated invasive infection with Aspergillus species. Three patients had nocardiosis despite receiving prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) on an intermittent basis two or three times a week. These data show that nocardial infection is an important if infrequent complication of bone marrow transplantation and is associated with a high rate of invasive fungal infection. TMP-SMZ prophylaxis given intermittently does not reliably protect against infection.

The effects of bone morphogenetic protein-2, -4, and -6 on differentiation of rat osteoblast cells in vitro

The effects of bone morphogenetic protein-2 (BMP-2), -4, and -6 were tested on the differentiation of rat osteoprogenitor cells using a bone nodule-forming assay system, and the kinetics of their actions were investigated by double labeling for alkaline phosphatase (ALP) and bromodeoxyuridine (BrdU) uptake in log phase cultures. All BMPs stimulated bone nodule formation, with an optimal concentration of 25 ng/ml resulting in nodule numbers of approximately 250% of controls using BMP-4 and -6. BMP-2 showed reduced potency compared to either BMP-4 or -6. No evidence of chondrocytic differentiation was found in any of the cultures. The effect of BMPs on nodule formation was seen after only 24 h of exposure to BMPs, but only affected nodule numbers when added to early cultures. Nodule size and number of cells per nodule were increased with BMP6 only. Continuous or 24-h exposure to BMP-2 or -4 increased the number of postmitotic ALP-positive cells in log phase cultures, whereas BMP-6 increased the number of postmitotic ALP-negative cells. The results demonstrate that BMP-6, like other BMPs, can stimulate osteoblast differentiation independent of any chondrogenic effects and suggest that an early osteoprogenitor cell is an important target cell for the action of BMPs during bone induction. Overall, BMP-2 and -4 showed differences in potency in the assay systems used, but had qualitatively similar effects. In contrast, the qualitative differences found with BMP-6 suggest that BMP-6 may be acting principally on an early stage osteoprogenitor cell.

The molecular basis of canine pyruvate kinase deficiency

Inherited hemolytic anemia due to pyruvate kinase (PK) deficiency is an autosomal recessive disease of the Basenji dog that closely resembles human PK deficiency. Characterization of transcriptional and translational expression of PK isozymes and sequencing of DNA from normal and mutant dogs were performed to identify the genetic defect in Basenji dogs. Measurement of erythrocytic PK activity by ion exchange chromatography, substrate kinetics, immunologic reactivity, and electrophoretic mobility suggests that M2-type PK is the major form of PK activity in erythrocytes of PK-deficient dogs, in contrast to normal dogs having only R-type PK activity. Both R-type and M2-type PK mRNA are detectable in reticulocytes of PK-deficient dogs, suggesting that the aberrant isozyme expression is not due to a failure in the erythroid maturational switch from M2- to R-type isozymes. Nucleotide sequence data from wild-type and mutant R-type PK cDNA identified a single nucleotide deletion, delta C433, in the mutant cDNA. The deduced amino acid sequence predicts a truncated mutant protein devoid of all residues contributing to the catalytic site of the wild-type protein. In the absence of R-type PK activity, there is anomalous compensatory expression of M2-type PK in erythroid cells of PK-deficient Basenjis. The PK-deficient Basenji dog may be valuable in somatic cell gene therapy trials involving manipulation of hematopoietic stem cells.

Effect of an angiotensin-converting enzyme inhibitor on blood pressure and erythropoiesis in rats

Positive correlation between systolic blood pressure and plasma renin substrate was demonstrated in Wistar-Kyoto rats when plasma renin substrate was reduced to within a range of 18 and 88% of control values with varying amounts of ramipril. When ramipril was given in amounts that had a maximum effect on systolic blood pressure, marked changes in erythropoietin, reticulocyte count and hematocrit % were observed. Consistent blood pressure-lowering effect was evident for several weeks after ramipril withdrawal. Furthermore, blood pressure obtained 3 days after the rats were taken off ramipril correlated positively with the hematocrit % measured while the rats were still on ramipril (r = 0.83; P less than 0.001). Mean blood volume of 17 rats receiving ramipril was similar to that of the 10 control rats. Plasma and renal renin substrate were highly and positively correlated (r = 0.86; P less than 0.001). Inasmuch as plasma renin substrate is rate-limiting for angiotensin I, it may reflect intrarenal AII and prove to be a useful clinical assessment of converting enzyme inhibition. The increased levels of renin, renin substrate and packed cell volume seen in rats fed Purina basal diet (10% fat) as compared with rats fed Purina lab chow (4.5% fat), support the working hypothesis that intrarenal angiotensin II controls both blood pressure and erythropoiesis.

Insulin and phorbol myristic acetate induce ornithine decarboxylase in Reuber H35 rat hepatoma cells by different mechanisms

Reuber H35 rat hepatoma cells respond to insulin or to tumor promoting phorbol esters with an increase in ornithine decarboxylase enzyme activity. This occurs in a time- and dose-dependent manner with both types of agonist. We report here that the increase in ornithine decarboxylase activity with optimal concentrations of both agonists is additive. Furthermore, the initial increase is dependent on continued RNA and protein synthesis. We also find that both of these agonists cause an increase in mRNA coding for ornithine decarboxylase in a time- and dose-dependent manner which suggests that the increase in enzyme activity can be accounted for by the increase in transcript levels. The difference in the time course of induction by the agonists, the additivity of induction by the two agonists, the differential sensitivity of induction to cycloheximide and RNA synthesis inhibitors, and the observation that phorbol myristic acetate causes a further increase in ornithine decarboxylase activity and transcript levels in cells already maximally induced by insulin suggest that these two agonists act through separate mechanisms.

Effect of a renin-system inhibitor on blood-vessel adaptation in spontaneously hypertensive rats

We tested the hypothesis that a metabolic error may be the triggering mechanism which leads to blood-vessel hypertrophy and hypertension. Young spontaneously hypertensive rats (SHR) were fed a moderately high salt diet to exacerbate the purported metabolic error. Haematocrit values and rubidium transport were measured as evidence of renal ATP deficiency and blood-vessel adaptation. The renin system was inhibited in two groups of SHR by giving them enalapril to determine whether angiotensin II was involved in blood-vessel adaptation. Spontaneously hypertensive rats fed the moderately high salt diet had higher haematocrit values than normotensive rats fed the same diet or SHR fed Purina rat food, suggesting a renal ATP deficiency. Spontaneously hypertensive rats had higher Na+,K+-ATPase activity in thoracic aorta after 60 min incubation than a similar group given enalapril (P less than 0.001), suggesting blood-vessel adaptation. Possibly, angiotensin II within the vasa vasorum stimulates hypertrophy which, according to the Folkow hypothesis, leads to higher blood pressure, but may concomitantly increase the respiratory chain units which provide ATP for renal function and ion transport.

Lipopolysaccharide receptors on lymphocytes. I. Lack of immunologic recognition of a putative LPS receptor on LPS-responder lymphocytes by LPS-nonresponder mice

We have examined the potential immunogenicity of viable lymphocytes from C3HeB/FeJ responder mice adoptively transferred into congenic nonirradiated C3H/HeJ nonresponder mice. Immunologic rejection or acceptance of donor cells was employed as indirect evidence for the presence or absence of an antigenically distinct "LPS receptor" present on donor lymphocytes. Immunogenicity was evaluated by in vitro assessment of the subsequent proliferative response of recipient splenocytes to protein-free LPS after multiple i.p. injections of responder lymphocytes. Control experiments have made use of syngeneic donor lymphocytes differing immunologically by the presence of the H-Y minor histocompatibility antigen. The results of these experiments provide evidence for the concept that if the phenotypic difference between LPS responder and nonresponder mice is also expressed antigenically in the form of an LPS receptor, that antigenic difference is significantly less immunogenic than a minor histocompatibility antigen.

Lipopolysaccharide receptors on lymphocytes. I. Lack of immunologic recognition of a putative LPS receptor on LPS-responder lymphocytes by LPS-nonresponder mice

We have examined the potential immunogenicity of viable lymphocytes from C3HeB/FeJ responder mice adoptively transferred into congenic nonirradiated C3H/HeJ nonresponder mice. Immunologic rejection or acceptance of donor cells was employed as indirect evidence for the presence or absence of an antigenically distinct "LPS receptor" present on donor lymphocytes. Immunogenicity was evaluated by in vitro assessment of the subsequent proliferative response of recipient splenocytes to protein-free LPS after multiple i.p. injections of responder lymphocytes. Control experiments have made use of syngeneic donor lymphocytes differing immunologically by the presence of the H-Y minor histocompatibility antigen. The results of these experiments provide evidence for the concept that if the phenotypic difference between LPS responder and nonresponder mice is also expressed antigenically in the form of an LPS receptor, that antigenic difference is significantly less immunogenic than a minor histocompatibility antigen.

Selective association of lipid-rich R-like lipopolysaccharide subunits with murine spleen cells

SDS-PAGE was used to analyze the subunit composition of 125I-lipopolysaccharide (LPS) in the cell-associated and supernatant fractions of murine spleen cells after culture with radiolabeled LPS from the smooth strain of E. coli O55:B5. Quantitative estimates from densitometric scans of autoradiographs indicated that certain R-like subunits were selectively enriched in cell-associated fractions by a factor of 2.8 as compared to native O55 LPS. Coincident with this selective enrichment was a 57% decrease in these subunits in supernatant fractions. In contrast, the level of polysaccharide-containing subunits in cell-associated fractions was equivalent to or less than the corresponding subunit in native LPS. LPS bound at 37 degrees C was capable of eliciting a significant B-lymphocyte proliferative response in responder spleen cells. However, this selective binding of lipid-rich R-like subunits to splenocytes is insufficient, by itself, to initiate a triggering event since it is both quantitatively and qualititatively indistinguishable in lymphoid cells from the LPS responder (C3HeB/FeJ) mouse and the LPS non-responder (C3H/HeJ) mouse.

Selective interaction between lymphocytes and lipid A subunits in lipopolysaccharide macromolecular aggregates

The interaction between bacterial lipopolysaccharides (LPS) and murine spleen cells was examined. The results indicate that lipid A-rich subunits, contained within the heterogeneous LPS macromolecule, associated selectively with spleen cells. In the LPS not associated with spleen cells, the relative amounts of lipid A-rich subunits were reduced; however, this reduction was not of a sufficient magnitude to be reflected in the stimulation of B cells. By constructing hybrid LPS macromolecules with various amounts of lipid A-rich subunits it was documented that mitogenic activity of B cells was relatively refractory to lipid A subunit composition. Furthermore, the presence of polysaccharide-rich subunits regulated downward the expression of lipid A-dependent activity.

Immunological identification of lactoferrin as a shared antigen on radioiodinated human sperm surface and in radioiodinated human seminal plasma

After lactoperoxidase-catalyzed iodination of either human sperm surface or human seminal plasma, a 72-76 kdalton component was resolved on SDS-7.5% polyacrylamide gels. The approximate molecular weight of this component was consistent with that of human lactoferrin, a major sperm-coating antigen. Immunoprecipitation of labeled sperm surface and of labeled seminal plasma with specific anti-human lactoferrin antibody identified lactoferrin as a constituent of this 72-76 kdalton component both on human sperm surface and in human seminal plasma. These data show that components which have been inferred to be shared because of similarities in biochemical characteristics also contain immunologically identical components.

Characterization of radiolabeled components of human sperm surface and seminal plasma

Externally oriented components on the human sperm cell surface and components in human seminal plasma were labeled by enzymatic iodination with lactoperoxidase and [¹²⁵I] NaI. SDS-7.5% PAGE of labeled sperm surface resolved one minor and four major components with approximate molecular weights of 92, 72, 46, 30, and 20K daltons, respectively. SDS-7.5% PAGE of labeled seminal plasma resolved five components with approximate molecular weights of 74, 51, 43, 28, and 20K daltons. Three of the five moieties seen on the sperm surface and in seminal plasma were similar in molecular weight. This suggested that these surface components were adsorbed from seminal secretions. Because the iodination procedure used labels both proteins and lipids, labeled sperm surface and labeled seminal plasma were subjected to isopycnic density gradient centrifugation to identify the chemical composition of the radioiodinated components. With human sperm surface, two areas of radioactivity were resolved in CsCl gradients, one corresponding to protein and the other to lipid. With human seminal plasma, only one area of radioactivity, corresponding to protein, was identified. Electrophoretic analysis of each peak of radioactivity obtained from the gradients demonstrated that all of the sperm surface and four of five seminal plasma components were in the protein fractions. All three of the seminal plasma components which correspond to sperm surface components were recovered in the protein fraction. This observation supports our hypothesis that some of the proteins labeled on the human sperm cell surface are adsorbed from seminal secretions.

Cell Surface Immunoglobulin. XIII. Distribution of IgM and IgD-Like Molecules on Small and Large Cells of Mouse Spleen

The distribution among murine spleen cells of a newly described class of surface immunoglobulin (Ig) with properties similar to human IgD was studied. Splenocytes were separated on the basis of size and the surface Ig on large cells (sedimenting faster than 6 mm/hr in a 1 × G velocity gradient) and small cells (sedimenting between 2.5 and 3.0 mm/hr) was analyzed. Spleen cells from young animals had virtually only IgM on the large cells but had substantial amounts of IgM and the IgD-like molecule (IgD) on small cells. Spleen cells from older animals, which have larger amounts of IgD, had IgM and IgD on both cell types; however, the amount of IgD relative to IgM on the large cells was always substantially less than that on the small ones. These observations taken together with those of other investigators support the hypothesis that a large lymphocyte with surface IgM is the precursor of a small lymphocyte with both surface IgM and IgD.

Cell surface immunoglobulin. XIII. Distribution of IgM and IgD-like molecules on small and large cells of mouse spleen

The distribution among murine spleen cells of a newly described class of surface immunoglobulin (Ig) with properties similar to human IgD was studied. Splenocytes were separated on the basis of size and the surface Ig on large cells (sedimenting faster than 6 mm/hr in a 1 times G velocity gradient) and small cells (sedimenting between 2.5 and 3.0 mm/hr) was analyzed. Spleen cells from young animals had virtually only IgM on the large cells but had substantial amounts of IgM and the IgD-like molecule (IgD) on small cells. Spleen cells from older animals, which have larger amounts of IgD, had IgM and IgD on both cell types; however, the amount of IgD relative to IgM on the large cells was always substantially less than that on the small ones. These observations taken together with those of other investigators support the hypothesis that a large lymphocyte with surface IgM is the precursor of a small lymphocyte with both surface IgM and IgD.

The late effects of selected immunosuppressants on immunocompetence, disease incidence, and mean life-span. II. Cell-mediated immune activity

The late effects of various immunosuppressive insults on cell-mediated immunity in mice were studied in an attempt to assess the role of immune surveillance in the aging process. Results were obtained using susceptibility to allogeneic tumor cell challenge, graft-versus-host reaction (GVHR), blastogenic response to PHA, a thymus derived T cell-specific plant mitogen, and cytolytic activity against allogeneic tumor cells as measures of immunologic activity. In vivo studies late in life show that resistance to allogeneic tumor cells is significantly decreased in thymectomized mice, whereas those treated with cortisone, cyclophosphamide and sublethal X-ray remain unchanged. Spleen cells from only the thymectomized and the sublethally irradiated mice show reduced activity in the GVHR. No difference is seen in the activity of bone marrow cells. Results consistent with these findings were obtained in in vitro studies. Thus spleen cells from thymectomized or sublethally irradiated mice show decreased activity is response to PHA, whereas no change is seen in spleen cells from other treated groups. Hence, surgical and physical insults are more likely to induce long-lasting immunosuppression in those immunocompetent tissues whose activity normally diminishes with advancing age. Furthermore, the degree of immunosuppression seen in this study is not of the order of magnitude that one could reasonably predict a significant decrease in mean life-span.

Effect of age on cell-mediated immunity in long-lived mice

The cytolytic ability of sensitized spleen cells to kill allogeneic target cells in vitro, a correlate of cell-mediated immune activity, was assessed in aging long-lived hybrid mice. There was about a 4-fold decline with age, of which about 2-fold could be accounted for by the decrease in relative numbers of immunocompetent precursor cell units. The terminally differentiated progeny cells of antigen-stimulated precursor cells of old mice were as efficient in killing target cells as were those of precursor cells of young mice. Thus, it would appear that a decrease in the proliferative and transforming capacities of antigen-stimulated precursor cells of old mice can account for the other 2-fold decline with age in the cytolytic activity. Cytolytic activity may not be the limiting function in resistance to tumour formation. This was indicated by the observation that resistance to allogeneic tumor cell challenge declines with age by as much as 500-fold in mice, showing only a 4-fold decline in their cytolytic activity.

An Improved Primary Response from Mouse Spleen Cells Cultured in Vivo in Diffusion Chambers

The optimum conditions for the hemolytic plaque-forming cell response of mouse spleen cells to sheep red blood cells (SRBC) in Millipore diffusion chambers were determined because of the wide applicability of the technique as an in vivo but closed system for the study of the immune response. The effect of pretreatment of chamber recipients with x-rays or cyclophosphamide, as well as the effects of chamber volume, culture medium, chamber detoxification and sterilization techniques, were investigated. The improvement in response over that previously reported by this laboratory was attributed to larger chamber volume, chamber detoxification twice over a 24-hr period, culture medium supplemented with horse serum, and lethally irradiated or cyclophosphamide-treated recipient C31F1 mice. With the improved conditions the peak primary response of mouse spleen cells to SRBC (104 direct plaque-forming cells per 106 nucleated cells harvested) was almost 20-fold greater than that obtained in the cell transfer system and about 5-fold greater than the best response obtained both in vitro and in situ. The burst size was also significantly larger than that obtained in the other systems, and culturing efficiency was twofold greater than previously reported from this laboratory for the diffusion chamber technique. The improved technique was used to determine the response of mouse spleen cells to SRBC in both allogeneic (across H-2 and non-H-2 barriers) and xenogeneic hosts. The enhanced response obtained by the present method is attributed to increased culturing efficiency and burst size, but not increased efficiency of interaction of the cells initiating the response.