Randomized controlled trial of pilocarpine hydrochloride for the moderation of oral mucositis during autologous blood stem cell transplantation

Pilocarpine hydrochloride has been reported to increase salivation and decrease oral mucositis in patients receiving head and neck radiotherapy, but there is only one report of its use in a cancer chemotherapy patient population. This prospective, double-blinded, randomized, placebo-controlled trial was undertaken to determine the efficacy of pilocarpine for the moderation of oral mucositis during autologous blood stem cell transplantation. Subjects were randomized to receive a 5 mg tablet of pilocarpine, or a placebo, during and following chemotherapy. Subjects were seen every other day and evaluated for gingival, oral, and oropharyngeal mucositis; nutrition; oral hygiene; eating; speaking; sleeping; pain at rest and/or with swallowing; and mouth dryness. We recorded the mean and highest scores and duration of problems, along with white blood cell counts and differentials, and the use of systemic narcotics for oral mucosal pain. We enrolled and randomized 36 subjects, and there were no statistically or clinically significant differences for the primary outcome of severity of mucositis and no clinically significant differences in any of the other outcome measures. Pilocarpine has no benefit for the moderation of the incidence, severity, or duration of mucositis in patients receiving autologous blood stem cell transplantation.

Treatment of chronic myelogenous leukemia with autologous bone marrow transplantation followed by roquinimex

Unmanipulated autologous bone marrow transplant (ABMT) offers patients with chronic myelogenous leukemia (CML) a long-term survival of 10%, at best. Immunotherapy has a role in the myeloid leukemias, and there is increasing evidence that of all hematopoietic neoplasms, CML may be the most susceptible to immune regulation. Roquinimex is known to enhance T cell, NK cell and macrophage activity. A phase II study was initiated in March 1992 to evaluate the role of roquinimex in Ph chromosome-positive CML post ABMT. Patients were conditioned with busulfan/ cyclophosphamide followed by reinfusion of unmanipulated Ph-positive bone marrow stem cells (>1 x 108 NBC/kg). When engraftment of neutrophils (ANC) reached 100/microl, patients received oral roquinimex twice weekly, escalating to a maximal dose of 0.2 mg/kg in 2 weeks. Seventeen patients have entered the study; 11 in first chronic phase (CP1); two in second chronic phase (CP2) and four in accelerated phase (AP). All required significant myelosuppressive therapy prior to ABMT to maintain stable blood counts and most had also received prior interferon therapy. All patients survived the transplant. Subsequent toxicity consisted mainly of musculoskeletal aches and peripheral edema. Additionally, specific skin changes were observed including graft-versus-host-like disease and eccrine sweat gland necrosis. Eight out of 17 patients are alive 28-60 months post ABMT. Of the nine patients who died, two were in CP2 and three in AP. All patients in CP1 went into a complete hematological remission post ABMT and seven of the 11 patients had at least a major cytogenetic response (greater than 65% Ph-negative metaphases) at 1 year or beyond and four of the 11 patients had a complete cytogenetic response at 2 years or beyond. Cytogenetic response post transplant often developed over time and did not simply represent post ABMT engraftment with Ph-negative cells. The clinical and cytogenetic data in these patients are encouraging and suggest that roquinimex may have significant activity when given post ABMT to patients with Ph-positive CML.

Analysis of factors that correlate with mucositis in recipients of autologous and allogeneic stem-cell transplants

PURPOSE

To identify predictors of oral mucositis and gastrointestinal toxicity after high-dose therapy.

PATIENTS AND METHODS

Mucositis and gastrointestinal toxicity were prospectively evaluated in 202 recipients of high-dose therapy and autologous or allogeneic stem-cell rescue. Of 10 outcome variables, three were selected as end points: the peak value for the University of Nebraska Oral Assessment Score (MUCPEAK), the duration of parenteral nutritional support, and the peak daily output of diarrhea. Potential covariates included patient age, sex, diagnosis, treatment protocol, transplantation type, stem-cell source, and rate of neutrophil recovery. The three selected end points were also examined for correlation with blood infections and transplant-related mortality.

RESULTS

A diagnosis of leukemia, use of total body irradiation, allogeneic transplantation, and delayed neutrophil recovery were associated with increased oral mucositis and longer parenteral nutritional support. No factors were associated with diarrhea. Also, moderate to severe oral mucositis (MUCPEAK > or = 18 on a scale of 8 to 24) was correlated with blood infections and transplant-related mortality: 60% of patients with MUCPEAK > or = 18 had positive blood cultures versus 30% of patients with MUCPEAK less than 18 (P =.001); 24% of patients with MUCPEAK > or = 8 died during the transplantation procedure versus 4% of patients with MUCPEAK less than 18 (P =.001).

CONCLUSION

Gastrointestinal toxicity is a major cause of transplant-related morbidity and mortality, emphasizing the need for corrective strategies. The peak oral mucositis score and the duration of parenteral nutritional support are useful indices of gastrointestinal toxicity because these end points are correlated with clinically significant events, including blood infections and treatment-related mortality.

Autotransplantation for relapsed or refractory Hodgkin's disease: long-term follow-up and analysis of prognostic factors

Seventy consecutive patients with refractory or relapsed Hodgkin's disease who received high-dose chemotherapy followed by autologous stem cell rescue were analyzed to identify clinically relevant predictors of long-term event-free survival. High-dose therapy consisted primarily of carmustine (BCNU), etoposide, cytarabine and cyclophosphamide (BEAC). The 5-year Kaplan-Meier event-free survival (EFS) for the entire cohort was 32% (95% confidence interval; 18-45%) with a median follow-up of 3.6 years (range 7 months-7.6 years). The most significant predictor of improved survival was the presence of minimal disease (defined as all areas < or =2 cm) at the time of transplant: the 5 years EFS was 46 vs 10% for patients with bulky disease (P = 0.0002). Other independent predictors identified by step-wise regression analysis included the presence of non-refractory disease and the administration of post-transplant involved-field radiotherapy (XRT). Treatment-related mortality occurred in 13 of 70 patients: nine patients (13%) died within the first 100 days, mainly from cardiopulmonary toxicity. However, only one of 24 patients (4%) transplanted during the last 4.5 years died from early treatment-related complications. While high-dose therapy followed by autotransplantation led to long-term EFS of 50% for patients with favorable prognostic factors, a substantial proportion of patients relapsed, indicating that new therapeutic strategies are needed.

Treatment of multifocal lymphoma of bone with intensified ProMACE-CytaBOM chemotherapy and involved field radiotherapy

Primary bone involvement is an unusual extranodal presentation of non-Hodgkin lymphoma (NHL). The optimal treatment for this entity has not been determined. While solitary bone lymphomas can be eradicated with local radiation in 50% of patients, distant relapses occur frequently, and the treatment of patients with multifocal osseous disease, or those presenting with associated soft tissue invasion or adenopathy is even less satisfactory. Over a 4-year period, nine patients with multifocal bone lymphoma were treated with intensified versions of the ProMACE-CytaBOM regimen and involved-field radiation. Seven patients had diffuse large cell histology and two patients had diffuse mixed type. Seven patients survived event-free at a median follow-up of 2.3 years (range .5-3.5). In most survivors, there was little or no change in the abnormal radiographic bone findings despite the clinical response to therapy. In one patient, magnetic resonance imaging (MRI) established that bone infarction rather than relapse of lymphoma was the cause of a new lytic bone lesion that developed during treatment.

Pathogenesis and management of paroxysmal nocturnal haemoglobinuria

Over the past 30 years, our understanding of the pathogenesis of paroxysmal nocturnal haemoglobinuria (PNH) has increased dramatically. During that time, the events during complement activation and regulation have been described, the molecular basis for the exaggerated complement sensitivity of PNH cells has been uncovered, and the responsible gene mutation has been identified. It is now possible to relate almost all the protean manifestations of PNH to a single gene mutation in a haematopoietic stem cell. Unfortunately, our ability to manage these patients has not kept pace, and, with the exception of bone marrow transplantation, our major efforts are still directed toward control of complications rather than interruption of the disease process.

Autotransplantation for relapsed or refractory non-Hodgkin's lymphoma (NHL): long-term follow-up and analysis of prognostic factors

One hundred and thirty-six patients autografted for relapsed or refractory non-Hodgkin's lymphoma (NHL) were evaluated to assess long-term event-free survival and to identify important prognostic factors. High-dose therapy consisted primarily of carmustine (BCNU), etoposide, cytarabine, and cyclophosphamide (BEAC) followed by unpurged autologous stem cell rescue. The 5-year Kaplan-Meier event-free survival (EFS) for the entire cohort was 34% (95% confidence interval: 24-44%) with a median follow-up of approximately 3 years (range 0-7.5 years). For patients entering with minimal disease (defined as all areas < or = 2 cm), the 5-year EFS was 40 vs 26% for those entering with bulky disease (P = 0.0004). In the multivariate analysis, minimal disease on entry and administration of involved-field XRT post-transplant were significantly associated with improved EFS; the latter association was observed mainly in the cohort of patients with bulky disease. The overall 100-day treatment-related mortality rate was 4.4% (3% for the last 71 patients). New strategies are needed to reduce the high rate of relapse (50-60%) following auto-transplantation for relapsed or refractory NHL.

Treatment of the neutropenia of Felty syndrome

This review sets out to synthesize and critically evaluate the current reported data regarding therapeutic options for the neutropenia associated with Felty syndrome (Felty neutropenia). A MEDLINE search and bibliographies from recent reviews were used to identify trials and case reports that provided sufficient data to evaluate the effect of various interventions on both the neutropenia and the clinical course of patients with Felty syndrome. Data were obtained on baseline hematologic profiles, bone-marrow biopsies, and patient characteristics; length of follow-up; hematologic and clinical responses to the various interventions; and side-effect profiles. Treatment with hemopoietic growth factors or methotrexate can produce sustained hematologic and clinical responses with an acceptable side-effect profile. Splenectomy produces a long-term hematologic response in 80% of patients. Patients who do not respond hematologically have a higher incidence of non-fatal infections, but a significant minority (46%) do not experience any infections; the incidence of fatal infections is 12%, regardless of whether a hematologic response occurs. Of the patients who had infections prior to surgery, 55% did not experience further infections after splenectomy. Initial treatment of Felty neutropenia should consist of hemopoietic growth factors because of their rapid onset of action and relatively low incidence of side-effects. Splenectomy is a reasonable option if growth factors are ineffective and rapid amelioration of neutropenia is needed. Methotrexate offers a potentially promising alternative for the treatment of both the rheumatologic and the hematologic manifestations of Felty syndrome.

The effect of dexamethasone on functional properties of HL60 cells during all-trans retinoic acid induced differentiation. Are there implications for the retinoic acid syndrome?

Differentiation therapy for acute promyelocytic leukemia (APL) using all-trans-retinoic acid (ATRA) has improved the prognosis of the disease. ATRA therapy also causes a newly recognized clinical syndrome, the "retinoic acid syndrome" (RAS), which can be successfully managed with dexamethasone. Because aberrant function of maturing leukemic granulocytes may cause this syndrome, and because dexamethasone is useful clinically, we studied functional properties of maturing HL60 cells cultured in the presence and absence of dexamethasone. HL60 cells were cultured for 4 days with ATRA and studied daily to determine acquisition of mature neutrophil-like properties including phagocytosis, NBT reduction, actin polymerization, chemotaxis and adhesion molecule expression. Undifferentiated HL60 cells could not polymerize actin or reduce NBT, and exhibited only a minimal ability to undergo chemotaxis or ingest latex beads. Following 4 days of maturation with ATRA, the cells would increase F-actin content in response to interleukin-8, ingest latex beads, migrate in a chemotaxis chamber, reduce NBT, and express CD11b. When dexamethasone was added to the cells in culture, there was no major enhancement or suppression of these properties. We also studied the effect of dexamethasone on functional properties of normal neutrophils and found minimal if any effect on their function. Overall, these studies suggest that in vitro, dexamethasone has little effect on the function of leukemic and normal granulocytes. To further investigate the pathophysiology of the retinoic acid syndrome, future studies may need to use endothelial cells, cytokines, or granulocytes obtained from APL patients.

Changes in cytoskeletal actin content, F-actin distribution, and surface morphology during HL-60 cell volume regulation

Cell volume regulation occurs via the regulated fluxes of ions and solutes across the cell membrane in response to cell volume perturbations under anisotonic conditions. Our earlier studies in human promyelocytic leukemic HL-60 cells showed that volume-dependent changes in total cellular F-actin content occur concomitantly as an inverse function of acute cell volume changes in anisotonic media (Hallows et al., 1991, Am. J. Physiol., 261:C1154-C1161). Although treatment with cytochalasin under anisotonic conditions significantly reduced total cellular F-actin levels, cytochalasin did not significantly affect the ability of cells to undergo normal volume regulation responses, which suggested that these volume-dependent changes in F-actin content may not play a critical role in HL-60 cell volume regulation. To examine more closely the possible role of the actin cytoskeleton in HL-60 cell volume regulation, we quantitated changes in Triton-insoluble cytoskeletal actin in the presence and absence of cytochalasin and also observed changes in F-actin distribution and surface morphology during volume regulation. The quantity of cytoskeletal-associated F-actin, like total F-actin, shifts inversely with initial cell volume changes in anisotonic media; however, subsequent changes in cytoskeletal actin levels during volume regulation are not significant. The soluble F-actin pool in HL-60 cells may thus be more susceptible to the physicochemical effects of shifts in cell volume than the insoluble (cytoskeletal) F-actin pool. Twenty-five micromolar dihydrocytochalasin B (DHB) treatment dramatically lowers cellular cytoskeletal actin levels by approximately 75% under resting (isotonic) conditions, but there are no significant further changes in cytoskeletal actin as cells undergo anisotonic volume regulation in the presence of DHB. These results suggest that volume-dependent changes in the absolute amounts of cytoskeletal-associated F-actin are not critical for HL-60 cell volume regulation. However, because some portions of the actin cytoskeleton are resistant to cytochalasin disruption during volume regulation, a role for the cytoskeleton in the sensing and signaling of HL-60 cell volume regulatory responses cannot be rigorously excluded. Particular F-actin distribution patterns, as observed using confocal fluorescent microscopy, were correlated with particular phases of volume regulation. Also, comparison of cellular F-actin distribution with surface morphology (observed by scanning electronic microscopy) of cells during volume regulation reveals a positive correlation between surface blebs and increased cortical F-actin staining intensity.

Functional characteristics of mature granulocytes in a patient with acute promyelocytic leukemia treated with all-trans retinoic acid

All-trans retinoic acid (ATRA) is a differentiating agent that has been successfully used in the treatment of patients with acute promyelocytic leukemia (APL). Functional properties of peripheral blood neutrophils from a patient with APL during treatment with ATRA have been studied. Wright stain of patient neutrophils showed hypogranulation and loose nuclear chromatin when compared with normal neutrophils. These cells were of lower density than normal neutrophils and separated on density gradient centrifugation with mononuclear cells. Surface antigen expression by FACS distinguished these cells from lymphocytes. The histograms showed a population of larger cells expressing CD18 and CD11b, distinct from the smaller cells which did not express CD11b. fMLP caused an increase in intracellular calcium (measured spectrophotometrically) that was inhibited by the calcium chelator BAPTA. Actin polymerization following cell activation was measured using NBD-phallacidin staining and FACS. Both IL-8 and fMLP caused rapid increases using F-actin content (2.5-3.0 fold), which were of greater magnitude than generally seen with normal neutrophils. Treatment with BAPTA before activation with fMLP did not blunt the actin responses, despite complete inhibition of an intracellular calcium increase. In summary, neutrophils derives from differentiated APL cells express CD18/CD11b, and exhibit a similar degree of actin polymerization in response to fMLP and IL-8, independent of an increase in intracellular calcium. Although the actin responses are greater than normal neutrophils, most properties are similar, supporting the contention that these cells can protect the host. The exaggerated actin response to inflammatory mediators, however, may play a role in the 'retinoic acid syndrome'.

Patients > or = age 40 years undergoing autologous or allogeneic BMT have regimen-related mortality rates and event-free survivals comparable to patients < age 40 years

To evaluate the safety and efficacy of marrow transplantation for older adults, the regimen-related mortality and event-free survival for patients > or = 40 years were compared with those for patients < 40 years. Of 148 consecutive patients receiving autotransplants for lymphoma or Hodgkin's disease, 70 were < 40 years and 78 were > or = 40 years at the time of transplant, including 40 who were > or = 50 years and 12 who were > or = 60 years. Eleven patients (16%) in the younger age group died from transplant-related complications compared with 4 (5%) in the older age group. The 4-year actuarial event-free survivals (EFS) for the younger and older age groups were 43% and 48%, respectively. After adjustment for covariates with prognostic significance, older age was marginally associated with improved event-free survival (P = 0.08). Of 92 consecutive patients undergoing allogeneic BMT during the same period, 62 patients were < 40 years and 30 patients were > or = 40 years, including 8 patients > or = 50 years, and 1 patient > 60 years. Non-relapse mortality (including deaths from GVHD) occurred in 28 of the younger patients (45%) and 9 of the older patients (30%). The 3-year actuarial EFS for the younger patients was 26% vs. 56% for the patients > or = 40 years (P = 0.057). However, this difference was mainly due to the higher proportion of patients with CML and early-stage leukemia in the older age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute cell volume changes in anisotonic media affect F-actin content of HL-60 cells

Page C1160: K. R. Hallows, C. H. Packman, and P. A. Knauf.“Acute cell volume changes in anisotonic media affect F-actin content of HL-60 cells.” The acknowledgments should include the following sentence: K. R. Hallows is a student in the Medical Scientist Training Program funded by National Institute of General Medicine Sciences Grant T32 GM-07356.

Functional properties of HL60 cells matured with all-trans-retinoic acid and DMSO: differences in response to interleukin-8 and fMLP

All-trans-retinoic acid (ATRA) causes granulocyte differentiation in patients with acute promyelocytic leukemia. HL60 cells are frequently used as an in vitro model for studying granulocytes during maturation. We have previously studied actin polymerization in response to fMLP in HL60 cells undergoing DMSO induced maturation, and reported that IL-8 causes actin polymerization in neutrophils in a manner similar to fMLP. We now compare chemotaxis and actin polymerization in response to IL-8 and fMLP, and nitroblue tetrazolium (NBT) reduction in HL60 cells matured with ATRA and DMSO. Cells cultured for 4 days with ATRA and DMSO showed morphologic evidence of maturation. NBD-phallacidin staining and flow cytometry were used to measure changes in F-actin content in response to IL-8 and fMLP. Uninduced cells were not capable of actin polymerization or chemotaxis. Cells matured with ATRA exhibited a 2.6-fold increase in F-actin content in response to IL-8, but only a 1.2-fold increase in response to fMLP. Cells matured with DMSO responded to both IL-8 and fMLP in an equal manner with 1.6-fold increases in F-actin. The 2 h migration for ATRA induced cells was 124 microns in response to IL-8, 107 microns with fMLP, and 105 microns in buffer. DMSO induced cells migrated 89 microns in response to IL-8, 106 microns with fMLP, and 66 microns in buffer. With maturation, 65% of the ATRA induced cells reduced NBT compared with only 15% of the DMSO induced cells. In summary, HL60 cells cultured in ATRA develop greater functional maturity than those cultured in DMSO, and a greater responsiveness to IL-8 than fMLP, a finding distinct from previously reported work in neutrophils.

The Rochester practice-based experience. An experiment in medical education

BACKGROUND

Recent changes in the organization and financing of medical practice have resulted in a shift of patient care from the hospital to ambulatory locations and dramatically changed the mix and severity of the inpatient population. Medical educators are concerned that hospitalized patients are not truly representative of the practice of internal medicine and may be unsuitable for the education of third-year medical students. The University of Rochester (NY) Department of Medicine recently established a "practice-based" component to complement the inpatient segment of the third-year medicine clerkship.

METHODS

Participating students work with a practicing internist for the second half of the 12-week clerkship. Students evaluate office and hospital patients in the internist's practice and attend didactic conferences. We used a multi-measurement curriculum evaluation system to assess the new program and compare it with the established hospital experience. Evaluation components included the following: logs in which students profiled their clinical activities; questionnaires that assessed opinions and satisfaction about the clerkship; group interviews with students; and visits to practice-based sites to interview both preceptor and student.

RESULTS

Practice-based students saw many more patients with a broader range of illnesses and had more observation and supervision from faculty than hospital-based students. Practice-based students discussed all of their patients with their preceptors, who were perceived as being excellent teachers. Hospital-based students, although generally positive, were also generally less enthusiastic about the amount and quality of teaching, observation, and supervision. Practice-based and hospital-based students achieved similar grades on the final examination and received a similar number of honors grades. Preceptors were enthusiastic in their endorsement of the practice-based experience and patient acceptance of students was high.

CONCLUSION

The practice-based experience is feasible and of equal academic rigor to the hospital experience. This realistic immersion into the daily activities of an internist provides an enriching balance to the traditional hospital-based clerkship.

Engagement of the T-cell antigen receptor by anti-CD3 monoclonal antibody causes a rapid increase in lymphocyte F-actin

Activation of protein kinase C (PKC) causes a rapid and sustained increase in the F-actin of T lymphocytes. Because the phosphatidylinositol pathway and the cytoskeleton play a role in lymphocyte activation, we examined the relationship between signal transduction and the F-actin increase in human blood T cells. Anti-CD3 monoclonal antibodies (mAbs) initiate signals which result in activation of T lymphocytes through the T-cell receptor (TCR), involving the phosphatidylinositol pathway, activation of PKC, and increasing intracellular calcium (Cai2+). The fluorescent probe NBD-phallacidin was used to examine the conformational state of actin following stimulation of T lymphocytes with anti-CD3 mAb. Each of three different murine anti-CD3 mAbs caused rapid increases in lymphocytic F-actin content, which was enhanced by cross-linking with a goat anti-mouse IgG. A maximally effective dose of the mAb Leu 4 caused a rise in cellular F-actin of 1.8-fold at 2 minutes and a three-fold increase in Cai2+. Ionomycin, 100 nM, caused a Cai2+ rise similar in magnitude to that caused by anti-CD3 mAb but had no effect on F-actin content. Inhibitors of PKC, 1(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), sphingosine, and sphinganine lowered the resting cellular F-actin and partially blocked the increase in F-actin caused by either anti-CD3 mAb or ionomycin; however, they had no effect on the rise in Cai2+. Cells leached of Ca2+ with EGTA and ionomycin exhibited no Cai2+ increase in response to anti-CD3 mAb or ionomycin; such cells retained the F-actin increase caused by anti-CD3 mAb. We conclude that stimulation of human T lymphocytes via the TCR causes an early rapid increase in F-actin content. Activation of PKC may play a role but the concomitant Cai2+ increase is neither sufficient nor necessary for the F-actin increase.

One hundred autotransplants for relapsed or refractory Hodgkin's disease and lymphoma: value of pretransplant disease status for predicting outcome

PURPOSE

One hundred autotransplants for Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) were examined prospectively to identify variables with prognostic significance.

PATIENTS AND METHODS

Ninety-six patients with relapsed or refractory HD or NHL underwent 100 autotransplants. Patients received high-dose carmustine (BCNU), etoposide, cytarabine, and cyclophosphamide (BEAC) followed by unpurged autologous stem-cell rescue.

RESULTS

The 3-year actuarial event-free survival (EFS) rate for the 47 HD patients is 49%, with a median followup duration of 2 years. For the 53 NHL patients, the 3-year actuarial EFS rate is 40%, with a median follow-up duration of 19 months. By multivariate analysis, minimal disease on admission (all areas < or = 2 cm) is associated with improved EFS (HD, P = .003, NHL, P = .03). The projected EFS rate for HD patients entering with minimal disease is 70% versus 15% for patients with bulky disease (P = .0001). The projected EFS rate for NHL patients with minimal disease is 48% versus 25% for patients with bulky disease (P = .04). Posttransplant involved-field radiotherapy, administered to 26 of the last 61 patients, was associated with an improved EFS rate for NHL patients (P = .015). The BEAC regimen was well tolerated by patients who entered the study with minimal disease (mortality rate, < 5%), but caused significant toxicity in patients with bulky disease (mortality rate, 25%).

CONCLUSION

Disease burden before autotransplantation is an important predictor of regimen-related toxicity and EFS. Posttransplant involved-field radiotherapy may improve outcomes in select patients with NHL. The BEAC regimen is safe and effective, particularly for patients with minimal disease.

The "bystander effect": tumor regression when a fraction of the tumor mass is genetically modified

Tumor cells expressing the herpes simplex virus thymidine kinase (HSV-TK) gene are sensitive to the drug ganciclovir (GCV). We demonstrate here that HSV-TK-positive cells exposed to GCV were lethal to HSV-TK-negative cells as a result of a "bystander effect." HSV-TK-negative cells were killed in vitro when the population of cultured cells contained only 10% HSV-TK-positive cells. The mechanism of this "bystander effect" on HSV-TK-negative cells appeared to be related to the process of apoptotic cell death when HSV-TK-positive cells were exposed to GCV. Flow cytometric and electron microscopic analyses suggested that apoptotic vesicles generated from the dying gene-modified cells were phagocytized by nearby, unmodified tumor cells. Prevention of apoptotic vesicle transfer prevented the bystander effect. The toxic effect of HSV-TK-positive cells on HSV-TK-negative cells was reproduced in an in vivo model. A mixed population of tumor cells consisting of HSV-TK-positive and HSV-TK-negative cells was inoculated s.c. into mice. Regression of the tumor mass occurred when the inoculum consisted of as few as 10% HSV-TK-expressing tumor cells. The bystander effect was also demonstrated in i.p. tumor studies. Initial experiments demonstrated that prolonged survival (> 70 days) occurred when a mixture containing 50% HSV-TK-positive and 50% HSV-TK-negative cells was injected i.p. followed by GCV treatment. Further, survival was prolonged for mice with a preexisting HSV-TK-negative i.p. tumor burden by injecting HSV-TK-positive cells and GCV. These results suggest that genetic modification of tumor cells may be useful for developing cancer therapies.

Signal pathway regulation of interleukin-8-induced actin polymerization in neutrophils

Interleukin-8 (IL-8), a recently described peptide cytokine, is a neutrophil chemoattractant and activator that exerts effects similar to fMLP, yet their receptors and their roles in pathophysiology differ. The effect of IL-8 on the neutrophil cytoskeleton has not been well studied; therefore, we compared and contrasted the effects of IL-8 and fMLP on neutrophil actin conformation and on the signal pathway regulation of actin responses. IL-8 caused a rapid, dose-dependent increase in neutrophil F-actin content within 30 seconds. The maximum increase was twofold. These changes were accompanied by the development of F-actin-rich pseudopods, as noted with fluorescence microscopy and scanning electron microscopy. Selected biochemical inhibitors were used to study the regulation of the IL-8-induced actin changes. Incubation of neutrophils with 2 micrograms/mL pertussis toxin resulted in a 67% inhibition of the IL-8-induced F-actin increase. The protein kinase C (PKC) inhibitors, staurosporine and H7, did not inhibit the increase in F-actin caused by IL-8. IL-8 caused a rapid increase in neutrophil intracellular calcium that could be completely inhibited by the chelating agent 1,2-bis(o-aminophenoxy)ethane-N,N-N',N'-tetraacetic acid (BAPTA). However, BAPTA-treated neutrophils retained the ability to increase F-actin in response to IL-8. Similar results were seen with fMLP, indicating that, similar to fMLP, the IL-8-induced actin response is mediated through pertussis-toxin-sensitive G-proteins but is neither dependent on PKC nor increases in cytosolic calcium. Thus, although IL-8 and fMLP exert their effects on neutrophils through different receptors, the signal transduction pathways used and the effects on actin conformation and pseudopod formation are similar.

Acute cell volume changes in anisotonic media affect F-actin content of HL-60 cells

To investigate the possible role of the cytoskeleton in volume regulatory responses of human promyelocytic leukemic (HL-60) cells, we monitored and modulated the F-actin content of these cells undergoing volume regulation in anisotonic media. Initial volume changes of HL-60 cells suspended in hypertonic media followed a Van't Hoff relationship, and intracellular F-actin content during volume regulatory responses in anisotonic media changed concomitantly as an inverse function of the volume shifts. These F-actin changes were shown to be an explicit function of cell volume and not tonicity of the medium. The data fit with the idea that changes in affinity of actin-binding proteins (ABPs) for actin and/or changes in the overall effective critical concentration of actin occur during acute cell volume changes, producing shifts in the relative amounts of G- and F-actin. Treatment of HL-60 cells with dihydrocytochalasin B (DHB), which perturbs cellular actin assembly, lowered resting levels of intracellular F-actin but did not prevent volume-associated F-actin changes in anisotonic media. Despite the lowered F-actin levels, HL-60 cells in the presence of DHB still undergo normal volume regulatory responses. Thus the absolute amount of intracellular F-actin does not appear to be critical for volume regulation in HL-60 cells.

Cardiac arrest after autologous marrow infusion

A 27-year-old woman undergoing autologous bone marrow transplantation for relapsed, refractory Hodgkin's disease developed acute non-cardiogenic pulmonary edema immediately after transfusion of autologous bone marrow. A few similar cases in the literature are identified. Although the precise mechanisms for these rare reactions are not clear, several possibilities including anaphylaxis due to dimethylsulfoxide, leukoagglutination, complement activation, and transient left ventricular dysfunction are proposed and discussed. Features which might allow patients at risk for similar events to be identified include the presence of active pulmonary tumor, and a history of dyspnea and pulmonary infiltrates following transfusion of homologous blood products.

Signal transduction and the regulation of actin conformation during myeloid maturation: studies in HL60 cells

Maturation of human myeloid cells is associated with quantitative and qualitative changes in protein kinase C (PKC) and increases in N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) receptors, actin, and actin regulatory proteins. We have studied the actin responses and cell shape changes caused by FMLP and its second messenger pathways in HL60 cells undergoing neutrophilic maturation. In uninduced cells, the PKC activators 12-O-tetradecanoyl phorbol-13-acetate (TPA), bryostatin, and 1-oleyl-2-acetylglycerol (OAG) resulted in 15% to 30% decreases in F-actin, whereas FMLP had no effect. Ionomycin had no effect on actin but did cause a 10-fold increase in intracellular calcium. Cells grown for 24 hours in 1% dimethyl sulfoxide (DMSO) acquired the ability to polymerize actin in response to FMLP and ionomycin. TPA continued to cause a decrease in F-actin at 24 hours, but caused an increase in F-actin at 48 to 72 hours of maturation. The PKC inhibitor 1-5-isoquinolinesulfonyl 2-methylpiperazine (H7) partially blocked the F-actin increase caused by TPA in induced cells, but had no effect on the decrease in F-actin caused by TPA in uninduced cells or the increase in F-actin seen in FMLP-treated neutrophils. F-actin rich pseudopods developed following TPA or FMLP stimulation of induced HL60 cells; in uninduced cells neither agent caused pseudopod formation but TPA caused a dramatic loss of surface ruffles. The ability of FMLP and ionomycin to elicit a neutrophil-like actin response in HL60 cells within 24 hours after DMSO treatment shows that the actin regulatory mechanism is mature by that time. The inability of ionomycin to increase F-actin in uninduced cells supports the view that calcium increases alone are insufficient for actin polymerization. The longer maturation time required for HL60 cells to develop an actin polymerization response to TPA compared with FMLP, coupled with the inability of H7 to block the FMLP-mediated F-actin increase in neutrophils, suggests that the F-actin increase caused by FMLP is not mediated solely by PKC. Lastly, the TPA-induced F-actin decrease and shape changes in uninduced HL60 cells, and the longer time required for a "mature" response to TPA, may reflect immaturity in the PKC isoenzyme pattern rather than immaturity of the actin regulatory mechanism.

Control of actin conformation in AML myeloblasts: the effects of bryostatin and TPA

Protein kinase C (PKC), an enzyme involved in signal transduction, is the receptor for both the tumor-promoting phorbol esters and the anti-neoplastic bryostatins. In many cells, phorbol esters and bryostatins cause similar effects; we have found that both agents increase actin polymerization in neutrophils. In some cells, however, the two agents result in different cell processes; we have found consistently different effects of these agents on actin conformation in myeloblasts obtained from leukemic patients. The patients tested all had increases in F-actin in response to 12-O-tetradecanoylphorbol-13-acetate (TPA) and most had decreases in F-actin in response to bryostatin. The data suggests that leukemic myeloblasts have a different cytoskeletal response to a tumor promoter and an antineoplastic agent despite their common receptor.

Protein kinase C modulates actin conformation in human T lymphocytes

We studied the effect of activators and inhibitors of protein kinase C on actin conformation in human blood lymphocytes by flow cytometry and gel electrophoresis. PMA, 1-oleyl-2-acetyl-glycerol, and mezerein, activators of protein kinase C, caused an increase in lymphocyte F-actin within 2 to 5 min. After stimulation with PMA, lymphocytes formed pseudopods containing an increased concentration of F-actin and had an increase of actin in the Triton-insoluble cytoskeletal fraction. Sphingosine and H-7, inhibitors of protein kinase C activation, inhibited the increase in F-actin induced by PMA. The increase in F-actin in response to PMA was striking in Th and Ts lymphocytes (2- to 3-fold increase), but B lymphocytes had only a slight increase (1.15-fold). Thus, activation of protein kinase C modulates actin conformation specifically in T lymphocytes.

Protein kinase C modulates actin conformation in human T lymphocytes

We studied the effect of activators and inhibitors of protein kinase C on actin conformation in human blood lymphocytes by flow cytometry and gel electrophoresis. PMA, 1-oleyl-2-acetyl-glycerol, and mezerein, activators of protein kinase C, caused an increase in lymphocyte F-actin within 2 to 5 min. After stimulation with PMA, lymphocytes formed pseudopods containing an increased concentration of F-actin and had an increase of actin in the Triton-insoluble cytoskeletal fraction. Sphingosine and H-7, inhibitors of protein kinase C activation, inhibited the increase in F-actin induced by PMA. The increase in F-actin in response to PMA was striking in Th and Ts lymphocytes (2- to 3-fold increase), but B lymphocytes had only a slight increase (1.15-fold). Thus, activation of protein kinase C modulates actin conformation specifically in T lymphocytes.

Aberrant immunoglobulin and c-myc gene rearrangements in patients with nonmalignant monoclonal cryoglobulinemia

The status of the immunoglobulin (Ig) genes was investigated in patients with idiopathic nonmalignant monoclonal IgG cryoglobulinemia (NCG). In NCG, monoclonal antibodies are synthesized at an accelerated rate by nonmalignant B lymphocytes. In order to determine whether this high production rate is related to a clonal B cell expansion, the rearrangement of the Ig genes was investigated by Southern blot analysis of genomic DNA extracted from the peripheral blood lymphocytes of four NCG patients. In three of four (VI, BR, and CH) clonal expansion of B cells was detected using probes specific for the c kappa, JH, c gamma 4 genes (in accordance with detecting IgG kappa cryoproteins in these patients). BamHI digestion of DNA from VI and BR produced three rearranged fragments which cohybridized with JH and c mu probes. This finding suggested the presence of additional nonsecretory B cell clones and/or disruption of the gene segments spanned by and detected with the probes. In VI the idiotype of the IgG cryoglobulin was also detected in association with IgM in the supernatant of Epstein-Barr virus-stimulated B lymphocytes using a murine monoclonal anti-idiotypic antibody. In addition, the possibility of aberrant gene rearrangements was supported by noting the alteration of the c-myc gene locus in genomic DNA from peripheral blood leukocytes of VI and CH. Northern blot analysis of RNA isolated from peripheral blood B cells of VI and CH demonstrated aberrant transcripts of the c-myc gene, showing an active role of the altered c-myc locus. Detection of c-myc rearrangement in NCG patients clearly shows that this event may not be a final step in malignant B cell transformation; however, it may be related to the clonal expansion and high rate of cryoglobulin synthesis of nonmalignant B lymphocytes.

Aberrant immunoglobulin and c-myc gene rearrangements in patients with nonmalignant monoclonal cryoglobulinemia

The status of the immunoglobulin (Ig) genes was investigated in patients with idiopathic nonmalignant monoclonal IgG cryoglobulinemia (NCG). In NCG, monoclonal antibodies are synthesized at an accelerated rate by nonmalignant B lymphocytes. In order to determine whether this high production rate is related to a clonal B cell expansion, the rearrangement of the Ig genes was investigated by Southern blot analysis of genomic DNA extracted from the peripheral blood lymphocytes of four NCG patients. In three of four (VI, BR, and CH) clonal expansion of B cells was detected using probes specific for the c kappa, JH, c gamma 4 genes (in accordance with detecting IgG kappa cryoproteins in these patients). BamHI digestion of DNA from VI and BR produced three rearranged fragments which cohybridized with JH and c mu probes. This finding suggested the presence of additional nonsecretory B cell clones and/or disruption of the gene segments spanned by and detected with the probes. In VI the idiotype of the IgG cryoglobulin was also detected in association with IgM in the supernatant of Epstein-Barr virus-stimulated B lymphocytes using a murine monoclonal anti-idiotypic antibody. In addition, the possibility of aberrant gene rearrangements was supported by noting the alteration of the c-myc gene locus in genomic DNA from peripheral blood leukocytes of VI and CH. Northern blot analysis of RNA isolated from peripheral blood B cells of VI and CH demonstrated aberrant transcripts of the c-myc gene, showing an active role of the altered c-myc locus. Detection of c-myc rearrangement in NCG patients clearly shows that this event may not be a final step in malignant B cell transformation; however, it may be related to the clonal expansion and high rate of cryoglobulin synthesis of nonmalignant B lymphocytes.

The effects of sulfhydryl inhibitors and cytochalasin on the cytoplasmic and cytoskeletal actin of human neutrophils

To better understand the changes that occur in cytoplasmic actin during cell movement, we studied the effect of inhibitors of cell movement on the molecular conformation of actin and its incorporation into the Triton-insoluble cytoskeleton of human neutrophils. The sulfhydryl reactive compound N-ethylmaleimide caused an increase in cellular F-actin as measured by uptake of the F-actin specific fluorescent probe 7-nitrobenz-2-oxadiazole-phallacidin. However, N-ethylmaleimide reduced the amount of actin associated with the Triton-insoluble cytoskeleton. Dithiobisnitrobenzoic acid, a sulfhydryl reagent that does not cross cell membranes efficiently, did not alter the F-actin content of neutrophils. The effect of N-ethylmaleimide was blocked by the presence of dithiothreitol, a donor of sulfhydryl groups. N-ethylmaleimide did not affect the polymerization of actin in a cell-free system. Cytochalasin B did not alter F-actin content of neutrophils but did decrease actin in cytoskeletons of resting neutrophils. Cytochalasin inhibited the increase in F-actin initiated by the chemoattractant N-formylmethionylleucylphenylalanine. We propose that N-ethylmaleimide blocks the stabilization of G-actin in cytoplasm, interferes with the incorporation of F-actin polymer into the cytoskeleton, and depolymerizes the cytoskeleton. In contrast cytochalasin stabilizes G-actin in the presence of chemotactic peptide. These data suggest that reversible conversion of G-actin to F-actin and incorporation of F-actin into the Triton-insoluble cytoskeleton are important for neutrophil movement.

Characterization of monoclonal IgG cryoglobulins: fine-structural and morphological analysis

The morphology of the amorphous, gelatinous, and crystalline varieties of monoclonal IgG cryoglobulins was analyzed by light and transmission and scanning electron microscopy. Each cryoglobulin had a characteristic fine structure that correlated with its gross morphology. Transmission electron microscopy showed that the amorphous precipitates were random and disorganized molecular clumps. In contrast, cryogels were thin-walled, well-organized, and hydrated strawlike clusters, whereas cryocrystals formed tightly compacted, highly structured molecular clusters. Crystals that formed in blood produced rouleaux, and analysis by scanning electron microscopy indicated that the crystals could form thick-walled, branching, macromolecular nets that could physically trap cells. The morphological properties provided visual impressions by which cryoglobulins could cause clinical disease secondary to vascular occlusion produced by self-associated IgG cryoglobulin molecules.

Maturation-associated changes in the peripheral cytoplasm of human neutrophils: a review

The process of hemopoietic stem cell differentiation and proliferation leads to a large number of precursor cells committed to the neutrophil lineage. These precursor cells undergo a further limited degree of proliferation but, most importantly, undergo a dramatic process of maturation which alters the phenotype of the cell from a myeloblast, which is incapable of normal circulation and function into a segmented neutrophil capable of chemokinesis, chemotaxis, particle ingestion, microbicidal action, and other functions required to subserve the inflammatory process. This review describes the changes in the cell surface and cell cytoplasm that occur during precursor cell maturation and, to the extent possible, correlates molecular and macromolecular changes during maturation with the development of functional capacity.

The mechanisms of sulfonylurea-induced immune hemolysis: case report and review of the literature

Chlorpropamide, a sulfonylurea antidiabetic drug, was found to be the etiologic agent in a patient with immune hemolytic anemia. Hemolysis was severe, and ceased promptly when the drug was discontinued. The direct antiglobulin test was positive for complement, and the indirect antiglobulin test was also positive when the drug, patient serum, and fresh serum complement were all present. In this patient, and in four other patients described in the literature, hemolysis was mediated by the immune complex mechanism. In reports of two other patients taking a sulfonylurea drug, a milder form of hemolysis was mediated by the hapten mechanism. Sulfonylurea drugs are widely used. Since immune complex-mediated hemolysis in these patients is dramatic, it is not likely to be missed. However, the slower, milder hemolysis mediated by the hapten mechanism may be more common than is realized. Such patients may have only mild anemia and a near-normal reticulocyte count, making the diagnosis difficult. It is thus important to consider drug-immune hemolysis in patients who become anemic while taking sulfonylurea drugs.

Neutrophilic eccrine hidradenitis associated with Hodgkin's disease and chemotherapy. A case report

A 44-year-old man with Hodgkin's disease developed fever and erythematous macules and plaques associated with doxorubicin, bleomycin, vinblastine, and dacarbazine chemotherapy. Biopsy results demonstrated a neutrophilic infiltrate around sweat glands and degeneration of eccrine glands. These findings are characteristic of neutrophilic eccrine hidradenitis, which, to our knowledge, has previously been reported only in patients with acute myelogenous leukemia who were receiving cytarabine chemotherapy. Neutrophilic eccrine hidradenitis may represent a reaction pattern to chemotherapeutic agents and may not be specific for a particular disease or drug.

High-density lipoprotein and its apolipoproteins inhibit cytolytic activity of complement. Studies on the nature of inhibitory moiety

Human high-density lipoprotein (HDL) and its apolipoproteins A-I and A-II inhibit complement-mediated lysis of human and sheep erythrocytes. This inhibitory activity under study is exerted after C9 is bound to membrane-associated C5b-8 complexes but prior to completed assembly and insertion of the C5b-9 complex. In this paper, we define some structure-activity relationships of the inhibitory moiety. With the exception of weak lytic inhibitory activity found in LDL/VLDL pools and in some unconcentrated minor fractions of plasma obtained by hydrophobic chromatography, all inhibitor activity was found in fractions which contained either apolipoprotein A-I, apolipoprotein A-II, or both. Intact HDL has a high level of inhibitor activity but delipidation by chloroform-methanol extraction was associated with an increase in activity on a protein-weight basis. Purified apolipoprotein A-I and apolipoprotein A-II exhibited equal inhibitory activity, greater than that exhibited by intact HDL. Nevertheless, ultracentrifugal fractions in which no free apolipoproteins could be demonstrated still possessed inhibitory activity. These experiments suggest that delipidation of HDL is not necessary for expression of inhibitor activity, although we could not rule out the possibility that apolipoproteins in dynamic equilibrium with HDL are responsible for the inhibitor activity observed in whole serum and plasma and in HDL preparations. Limited proteinase digestion completely abolished the inhibitory activity of partially delipidated HDL. Phospholipase C had little or no effect on the inhibitory activity of delipidated HDL, apolipoprotein A-I or apolipoprotein A-II, but reduced the inhibitory activity of intact HDL. These data suggest that the phospholipid polar headgroups are not necessary for inhibitory activity. However, the loss of these headgroups is associated with decreased activity, possibly due to increased hydrophobicity of HDL, or increased association among HDL micelles, and subsequent decrease in effective molar concentration of the inhibitory moiety.

Chemotactic peptide-induced changes in neutrophil actin conformation

The effect of the chemotatic peptide, N-formylmethionylleucylphenylalanine (FMLP), on actin conformation in human neutrophils (PMN) was studied by flow cytometry using fluorescent 7-nitrobenz-2-oxa-1,3-diazole (NBD)-phallacidin to quantitate cellular F-actin content. Uptake of NBD-phallacidin by fixed PMN was saturable and inhibited by fluid phase F-actin but not G-actin. Stimulation of PMN by greater than 1 nM FMLP resulted in a dose-dependent and reversible increase in F-actin in 70-95% of PMN by 30 s. The induced increase in F-actin was blocked by 30 microM cytochalasin B or by a t-BOC peptide that competitively inhibits FMLP binding. Under fluorescence microscopy, NBD-phallacidin stained, unstimulated PMN had faint homogeneous cytoplasmic fluorescence while cells exposed to FMLP for 30 s prior to NBD-phallacidin staining had accentuated subcortical fluorescence. In the continued presence of an initial stimulatory dose of FMLP, PMN could respond with increased F-actin content to the addition of an increased concentration of FMLP. Thus, FMLP binding to PMN induces a rapid transient conversion of unpolymerized actin to subcortical F-actin and repetitive stimulation of F-actin formation can be induced by increasing chemoattractant concentration. The directed movement of PMN in response to chemoattractant gradients may require similar rapid reversible changes in actin conformation.

Amino-sugars enhance recognition and phagocytosis of particles by human neutrophils

Neutrophils were examined for their ability to recognize and ingest beads coated with amino-derivatives of glucose, mannose, and galactose. Radioactive or fluorescent beads coated with any of the three sugars were ingested to an extent three times that observed with albumin-coated beads. Enhancement of ingestion of sugar-coated beads was much more evident when examined by electron micrographic studies. Inclusion of glucose or mannose in the medium with glucose- or mannose-coated beads caused a dose-dependent reduction of ingestion to control levels, but ingestion of galactose-coated beads was poorly inhibited. Similarly, galactose or fucose (6-deoxy-galactose) markedly inhibited ingestion of galactose-coated beads, but caused only a slight decrease in ingestion of glucose- or mannose-coated beads. Thus, neutrophils possess carbohydrate-binding membrane structures that can mediate recognition and ingestion of sugar-coated beads. Such carbohydrate recognition systems may underlie certain interactions of neutrophils and other surfaces.

Inhibition of the lytic action of cell-bound terminal complement components by human high density lipoproteins and apoproteins

Human serum lipoproteins are known to participate in or modify several immunologically relevant responses, including the inhibition of target cell lysis initiated by fluid-phase C5b-7 (reactive lysis). We now report that human high density lipoproteins (HDL) can inhibit the complement (C) lytic mechanism after C5b-7, C5b-8, and even C5b-9 have been bound to the target membrane. This inhibitory activity of serum or plasma copurifies in hydrophobic chromatography with antigenically detected apolipoprotein A-I (apoA-I), the major HDL apoprotein, and with HDL in CsCl density gradient ultracentrifugation. Although HDL is more active than its apoproteins in fluid-phase inhibition of C5b-7-initiated reactive lysis, the HDL apoproteins are more effective after C5b-7, C5b-8, or C5b-9 have become bound to human or sheep erythrocytes (E). Highly purified HDL apoproteins, apoA-I and apoA-II, both have greater inhibitory activity than whole HDL on a protein weight basis, and some evidence has been obtained that apoA-I dissociating spontaneously from HDL may be the principal inhibitory moiety in physiological situations. HDL lipids themselves are inactive. The HDL-related inhibitors are ineffective when incubated with EC5b-7 and removed before C8 and C9 are added, and only minimally effective on cell-bound C5b-8 sites before C9 is added. They exert their most prominent inhibitory activity after C9 has been bound to EC5b-8 at low temperature, but before the final temperature-dependent, Zn(++)-inhibitable membrane damage steps have occurred. Therefore, HDL or its apoproteins do not act to repair already established transmembrane channels, but might interfere either with insertion of C9 into the lipid bilayer or with polymerization of C9 at C5b-8 sites. This heat-stable inhibitory activity can be demonstrated to modify lysis of erythrocytes in whole serum, i.e., it does not depend upon artificial interruption of the complement membrane attack sequence at any of the above-mentioned stages. Contributions of the target membrane itself to the mechanism of inhibition are suggested by the observations that, in contrast to sheep or normal human E, lysis of guinea pig E or human E from patients with paroxysmal nocturnal hemoglobinuria is inhibited poorly. This is the first description of a naturally occurring plasma inhibitor acting on the terminal, membrane-associated events in complement lysis. Although further study is required to assess the physiologic or immunopathologic significance of this new function of HDL, the HDL apoproteins or their relevant fragments should be useful experimentally as molecular probes of the lytic mechanism.

Attachment of particle-bound IgG and complement to human neutrophils

The attachment of particle-bound IgG in a nonphagocytic system stimulates formation of a microfilament-rich, organelle-poor zone in the subjacent cytoplasm of human neutrophils. The attachment site is characterized by ruffling and invagination of the neutrophil membrane. Both IgG attachment and formation of the organelle-poor zone are inhibited by the microfilament inhibitor cytochalasin-B, but not by inhibitors of microtubules, such as colchicine or vinca alkaloids. In contrast, attachment of particle-bound complement is not inhibited by cytochalasin-B in doses known to disrupt actin filaments. There is no discernable change in the subjacent cytoplasm of the neutrophil in response to complement and the membrane attachment site is smooth, without ruffling or invagination. These studies disclose that both IgG-mediated attachment to neutrophils and its sequel, peripheral cytoplasmic reorganization, are mediated by cytochalasin-sensitive structures, possibly actin. Complement-mediated attachment to neutrophils is insensitive to high doses of cytochalasin, suggesting that actin integrity is not required.

Complement lysis of human erythrocytes. Differeing susceptibility of two types of paroxysmal nocturnal hemoglobinuria cells to C5b-9

Although enhanced sensitivity of erythrocytes to complement-mediated lysis is a hallmark of paroxysmal nocturnal hemoglobinuria (PNH), subpopulations of erythrocytes in such patients vary significantly in this respect. One PNH erythrocyte subpopulation (termed type III) comprises exquisitely sensitive cells, whereas type II PNH erythrocytes are intermediate in complement sensitivity between PNH type III and normal human erythrocytes. Differences in the action of the terminal complement components that would account for the differing lytic behavior of types II and III PNH erythrocytes have been proposed but not directly demonstrated. The present studies, making use of carefully selected cases with pure populations of type II or type III erythrocytes, confirm a prior observation that antibody-coated PNH erythrocytes of both types II and III display comparably supranormal C3 binding in whole human serum. However, when lysis was induced by the isolated C5b-9 membrane attack mechanism, bypassing the requirement for C3 binding, only type III PNH cells exhibited greater than normal lysis. This finding suggests that type III PNH erythrocytes have an additional membrane abnormality not present in type II cells. Thus, the differing lytic behavior of these two cell types in whole serum may reflect the additive effects on type III cells of both exaggerated C3 binding and enhanced sensitivity to C5b-9, whereas the more moderate lysis of type II PNH cells may be determined mainly or entirely by the earlier-acting mechanism producing augmented C3 binding. The failure of guinea pig C8 and C9, as opposed to human C8 and C9, to reveal the true lytic sensitivity of PNH-III E in our earlier study is illustrated, and its implications briefly discussed.

Studies on the Lytic Sensitivity of Paroxysmal Nocturnal Hemoglobinuria (PNH) Erythrocytes (E)

PNH E have an unexplained membrane defect making them highly susceptible to complement (C) lysis. Studies by others have found: 1) equal binding of antibody (Ab), C1 and C4, and similar C2 Tmax and decay, on PNH and normal human E; 2) markedly increased C3 binding by PNH E relative to Ab or C4 binding; 3) supranormal lysis per unit of C3 bound; 4) comparable numbers of 10nm electron microscopic (EM) ring lesions on lysed PNH and normal E membranes; and 5) in the presence of fluid phase and C5–C9, increased lysis of and C5 binding to PNH E, but equal lysis of PNH and normal E for a given quantity of C5 bound.

Our studies sought to further define the lytic behavior of PNH E. The PNH patients studied included cases with predominant populations of highly C-sensitive E (“type III”), or with intermediately sensitive E (“type II”), or with mixtures of E types.

Complement-induced ultrastructural membrane lesions: requirement for terminal components

The step in the complement (C) sequence at which 8- to 11-nm ring-shaped lesions are formed on antibody-coated erythrocytes (EA) has remained controversial. Some workers have concluded that these lesions appear at the C5 step and are not ultrastructural correlates of lysis; others hold that these lesions are formed only after the action of C8 and C9 in association with lysis. We have re-examined this problem by using sheep EA and human sera genetically lacking C5, C6, C7, or C8. Electron micrographs of negatively stained membranes (x 220,000) were read in blind fashion and the results correlated with 125I-C5 binding. Rare structures resemblind C-induced ring lesions were found on EA exposed to C5-deficient (C5D), C6D, C7D and C8D sera or to heated normal serum, with no significant differences among these sera (lesion density 0 to 0.26/mum2). Fresh normal serum (NHS) produced 140 to 220 ring lesions/mum2. C5 binding to EA in C8D serum was 60% of that observed in an NHS control; in C6D and C7D sera C5 binding was 4 to 11% of the normal value. Iodine treatment of sera (to enhance C5 uptake by C2 oxidation) increased C5 binding in C6D serum to 40 to 65% of that seen in native NHS; in iodine-treated C7D and C8D sera C5 binding was 250 and 440%, respectively, of the native NHS value. No increase in ring lesions was observed, however, except in the iodine-treated NHS. Thus, in whole serum, C5 binding is not sufficient to produce ultrastructural membrane rings in the absence of later-acting C components, at least through C8. The formation of ring lesions appears to have C requirements similar to those necessary for lysis.

Veno-occlusive disease of the liver after chemotherapy of acute leukemia. Report of two cases

Two adult male patients with acute leukemia developed a fatal Budd-Chiari-like illness while receiving 6-thioguanine. Both had previously received cytosine arabinoside. Antemortem and postmortem specimens of liver showed changes characteristic of toxic veno-occlusive disease. Similar findings have been described after ingestion of certain plant alkaloids and after treatment with arsphenamine, urethane, and ionizing radiation to the liver. We are unaware of any published reports of veno-occlusive disease of the liver after treatment with either 6-thioguanine or cytosine arabinoside. Although 6-thioguanine was most likely responsible for this syndrome, it is not possible to eliminate cytosine arabinoside as the causative agent. Since both drugs are occasionally used for benign conditions, physicians should be aware of this possible complication.

Complement-Induced Ultrastructural Membrane Lesions: Requirement for Late-Acting Components

Complement-induced ultrastructural ring-shaped changes in EA have been known since 1963. Initially it was thought that the entire C sequence was necessary for this phenomenon. However, Polley et al., using purified human C components added stepwise to EA, found ring structures on the membrane after the EAC14235 step. Stepwise addition of C6–C9 did not produce more rings, but lysis required the full C sequence. Polley also noted rings on EA exposed to C6-deficient (C6D) rabbit serum, but not C5D mouse serum. Other workers have been unable to find rings on either sheep E or liposomes by using C6D rabbit serum as C source. We have re-examined this problem by using several human sera each genetically deficient in one of the late components.

Sheep EA (108/ml) were incubated for 1 hr at 37°C with an equal volume of a 1:2 dilution of each C-deficient serum (C5D, C6D, C7D, C8D), normal human serum (NHS) and serum heated at 56°C for 30 min (CΔ).