Pre-B acute lymphoblastic leukemia cells may induce T-cell anergy to alloantigen

Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T- cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance.     

High incidence of monoclonal proteins in the serum and urine of chronic lymphocytic leukemia patients

Chronic lymphocytic leukemia (CLL) is generally considered a nonsecretory B cell immunoproliferative disorder. Conventional electrophoretic and immunoelectrophoretic methods have revealed serum monoclonal proteins in less than 10% of these patients. However, there is increasing experimental evidence from in vitro studies demonstrating that CLL cells may secrete immunoglobulins, particularly free light chains. We examined the serum and urine of 36 consecutive CLL patients for monoclonal proteins using sensitive immunochemical methods (high resolution agarose gel electrophoresis combined with immunofixation). The results obtained were correlated with the Rai stage, quantitative immunoglobulin levels, and lymphocyte membrane immunoglobulin phenotype of the leukemic cells. Twenty-three monoclonal proteins were identified in the serum or urine of 22 patients, an incidence of 61%. Six patients had serum monoclonal proteins, seven had only urinary monoclonal proteins, and nine had monoclonal proteins in serum and urine. In every instance the monoclonal protein was the same light chain type as expressed on the leukemic cells. Our findings suggest that the monoclonal proteins observed in the serum or urine of CLL patients are secretory products of the tumor cells and that their discovery is a function of the sensitivity of the method used for their detection.     

Role of accessory cells in cytokine production by T cells in chronic B- cell lymphocytic leukemia

We investigated the production of cytokines by highly purified T helper cells from B-cell chronic lymphocytic leukemia (B-CLL) patients stimulated by different activation pathways, and we studied the influence of various accessory cell populations on the pattern of the secretion of cytokines, including interleukin (IL)-2, IL-4, interferon- gamma (IFN-gamma), and IL-10. Neither a qualitative nor a quantitative difference in cytokine production and proliferative capacity was observed in CLL-derived purified T cells compared with normal individuals, when T cells were stimulated by different pathways, including CD3, CD2, and costimulation with CD28. Addition of autologous accessory cells (aAC), however, dramatically influenced the cytokine pattern of normal versus B-CLL-derived T cells. CLL cells as aAC caused a marked increase of IL-2, whereas IFN-gamma was only slightly induced and IL-4 was not influenced. In contrast, in normal individuals addition of aAC, which predominantly consisted of monocytes, resulted in a significant increase of IFN-gamma and a reduction of IL-4 secretion. IL-2 production was inhibited by higher concentrations of aAC. The increased stimulation of IL-2 production by CLL cells was not specific to the leukemic cell population, as purified B cells from normal individuals had the same effect. On the other hand, purified monocytes from CLL patients and controls both induced IFN-gamma production and inhibited IL-4 secretion. After antigen-specific stimulation with tetanus toxoid, cytokine secretion was influenced by the type of aAC in a similar pattern. We conclude that T helper cells derived from patients with B-CLL are intrinsically normal and that the predominance of B cells as accessory cells in CLL significantly alters the immune function of T helper cells in vitro.     

Phase I study of Topotecan, a new topoisomerase I inhibitor, in patients with refractory or relapsed acute leukemia

The purpose of this study was to define, in a phase I study in leukemia, the maximally tolerated dose (MTD), major toxicities, and possible antitumor activity of Topotecan, a new topoisomerase I (topo I) inhibitor. Topotecan was delivered by a 5-day continuous infusion every 3 to 4 weeks to patients with refractory or relapsed acute leukemia, at doses ranging from 3.5 mg/m2 to 18 mg/m2 per course. Twenty-seven patients were treated, including 17 patients with acute myelogenous or undifferentiated leukemia, 7 with acute lymphocytic leukemia, and 3 with chronic myelogenous leukemia in blastic phase. Severe mucositis was the dose-limiting toxicity occurring in two of five patients treated with Topotecan 11.8 mg/m2 per course; a third patient had prolonged myelosuppression. At the MTD of 10 mg/m2 per course, 1 of 12 patients had severe mucositis and 5 had mild-to- moderate mucositis. Nausea, vomiting, diarrhea, and prolonged myelosuppression were uncommon. Three patients (11%) achieved a complete response, two (7%) had a partial response, and one (4%) had a hematologic improvement. The overall complete plus partial response rate was 19%, and 24% in acute myelogenous or undifferentiated leukemia. A novel in vitro assay that quantifies Topotecan-stabilized topo I-DNA complexes in patient samples was used, which demonstrated heterogeneity in the ability of Topotecan to interact with topo I, the intracellular target of Topotecan. This phase I study defined the MTD of Topotecan to be 10 mg/m2 by continuous infusion over 5 days every 3 to 4 weeks in patients with refractory or relapsed acute leukemia. Severe mucositis was the dose-limiting toxicity. Future studies will define the precise activity of Topotecan in different leukemia subsets, its efficacy in combination with other antileukemic drugs, and correlations between Topotecan-induced topo I-DNA complex formation and individual patient response to Topotecan.     

Interferon-alpha stimulates production of interleukin-10 in activated CD4+ T cells and monocytes

In the present study, we investigated the effect of interferon-alpha (IFN-alpha) on the expression of interleukin-10 (IL-10) mRNA and protein synthesis in human monocytes and CD4+ T cells. In mononuclear cells, IFN-alpha induced expression of IL-10 mRNA and further enhanced lipopolysaccharide (LPS)-stimulated IL-10 expression. In purified monocytes, a strong expression of IL-10 mRNA induced by LPS was not further enhanced by IFN-alpha. In highly purified CD4+ T cells, IFN- alpha upregulated IL-10 mRNA upon activation with phytohemagglutinin and phorbol myristate acetate. In purified monocytes, an effect of IFN- alpha on IL-10 protein synthesis was dependent on costimulation with LPS. Maximal stimulation of IL-10 protein by IFN-alpha was seen after prolonged incubation periods of 48 to 96 hours, whereas IFN-gamma reduced IL-10 production in the early incubation period. Similar effects of IFN-alpha were observed in CD4+ T cells activated with CD3 and CD28 monoclonal antibodies. Addition of IFN-alpha caused an increase of IL-10 in culture supernatants of activated T-helper cells of more than 100% after 96 hours of incubation. In contrast, other cytokines, including IFN-gamma and IL-4, had no influence on IL-10 secretion stimulated by CD3 and CD28 in CD4+ T cells. In serum samples of IFN-alpha-treated individuals, we failed to detect an influence of cytokine treatment on IL-10 serum levels, confirming the requirement of additional activating signals for IFN-alpha-mediated effects on IL-10 synthesis. In conclusion, IFN-alpha enhances the late induction of IL- 10, which physiologically occurs upon stimulation of monocytes and T cells. Biologically, this effect might enhance the negative-feedback mechanism ascribed to IL-10, which limits inflammatory reactions.     

Radiation exposure from head computed tomography scans in pediatric trauma

Background

We have previously reported that children receive significantly less radiation exposure after abdominal and/or pelvis computed tomography (CT) scanning for acute appendicitis when performed at our children's hospital (CH) rather than at outside hospitals (OH). In this study, we compare the amount of radiation children receive from head CTs for trauma done at OH versus those at our CH.

Methods

A retrospective chart review was performed on all children transferred to our hospital after receiving a head CT for trauma at an OH between July 2012 and December 2012. These children were then blindly case matched based on date, age, and gender to children at our CH.

Results

There were 50 children who underwent head CT scans for trauma at 28 OH. There were 21 females and 29 males in each group. Average age was 7.01 ± 0.5 y at the OH and 7.14 ± 6.07 at our CH (P = 0.92). Average weight was 30.81 ± 4.69 kg at the OH and 32.69 ± 27.21 kg at our CH (P = 0.81). Radiation measures included dose length product (671.21 ± 22.6 mGycm at OH versus 786.28 ± 246.3 mGycm at CH, P = 0.11) and CT dose index (53.4 ± 2.26 mGy at OH versus 49.2 ± 12.94 mGy at CH, P = 0.56).

Conclusions

There is no significant difference between radiation exposure secondary to head CTs for traumatic injuries performed at OH and those at a dedicated CH.     

Serum uric acid predicts vascular complications in adults with type 1 diabetes: the coronary artery calcification in type 1 diabetes study

Epidemiologic evidence supports a link between serum uric acid (SUA) and vascular complications in diabetes, but it remains unclear whether SUA improves the ability of conventional risk factor to predict complications. We hypothesized that SUA at baseline would independently predict the development of vascular complications over 6 years and that the addition of SUA to American Diabetes Association’s ABC risk factors (HbA1c, BP, LDL-C) would improve vascular complication prediction over 6 years in adults with type 1 diabetes. Study participants (N = 652) were 19–56 year old at baseline and re-examined 6 years later. Diabetic nephropathy was defined as incident albuminuria or rapid GFR decline (>3.3 %/year) estimated by the CKD-EPI cystatin C. Diabetic retinopathy (DR) was based on self-reported history, and proliferative diabetic retinopathy (PDR) was defined as laser eye therapy; coronary artery calcium (CAC) was measured using electron-beam computed tomography. Progression of CAC (CACp) was defined as a change in the square-root-transformed CAC volume ≥2.5. Predictors of each complication were examined in stepwise logistic regression with subjects with complications at baseline excluded from analyses. C-statistics, integrated discrimination indices and net-reclassification improvement were utilized for prediction performance analyses. SUA independently predicted development of incident albuminuria (OR 1.8, 95 % CI 1.2–2.7), rapid GFR decline (1.9, 1.1–3.3), DR (1.4, 1.1–1.9), PDR (2.1, 1.4–3.0) and CACp (1.5, 1.1–1.9). SUA improved the discrimination and net-classification risk of vascular complications over 6 years. SUA independently predicted the development of vascular complications in type 1 diabetes and also improved the reclassification of vascular complications.     

Elsibucol inhibits atherosclerosis following arterial injury: Multifunctional effects on cholesterol levels,oxidative stress and inflammation

Background: Elsibucol is a metabolically stable derivative of probucol with antioxidant, anti-inflammatory and antiproliferative properties. Here we investigated the effect of elsibucol on the development of atherosclerosis following arterial injury in hypercholesterolemic rabbits. Methods and results: New Zealand White rabbits were fed a high cholesterol diet that was supplemented or not with 0.5% elsibucol, 1% elsibucol or 1% probucol. An angioplasty of the iliac artery was performed after 3 weeks of diet. We found that treatment with elsibucol significantly decreases blood total cholesterol, LDLc and triglyceride levels. This is associated with a significant 46% reduction of neointimal hyperplasia following arterial injury. Interestingly, the effect of elsibucol on cholesterol levels and neointimal formation appears to be more pronounced than that of probucol. In vitro, elsibucol reduces vascular smooth muscle cell proliferation without affecting cell viability. In vivo, treatment with elsibucol is associated with a significant reduction of cellular proliferation (PCNA immunostaining), oxidative stress (nitrotyrosine immunostaining), VCAM-1 expression and macrophage infiltration in injured arteries. Despite its potent effect on neointimal hyperplasia, elsibucol does not prevent endothelial healing (Evans blue staining) following arterial injury. Conclusions: In hypercholesterolemic animals, elsibucol inhibits atherosclerosis and preserves endothelial healing following arterial injury. The mechanisms involved include lowering of blood cholesterol levels together with a reduction of oxidative stress and inflammation in injured arteries.     

Construct validity of individual and summary performance metrics associated with a computer-based laparoscopic simulator

Background

Computer-based surgical simulators capture a multitude of metrics based on different aspects of performance, such as speed, accuracy, and movement efficiency. However, without rigorous assessment, it may be unclear whether all, some, or none of these metrics actually reflect technical skill, which can compromise educational efforts on these simulators. We assessed the construct validity of individual performance metrics on the LapVR simulator (Immersion Medical, San Jose, CA, USA) and used these data to create task-specific summary metrics.

Methods

Medical students with no prior laparoscopic experience (novices, N = 12), junior surgical residents with some laparoscopic experience (intermediates, N = 12), and experienced surgeons (experts, N = 11) all completed three repetitions of four LapVR simulator tasks. The tasks included three basic skills (peg transfer, cutting, clipping) and one procedural skill (adhesiolysis).

Results

We selected 36 individual metrics on the four tasks that assessed six different aspects of performance, including speed, motion path length, respect for tissue, accuracy, task-specific errors, and successful task completion. Four of seven individual metrics assessed for peg transfer, six of ten metrics for cutting, four of nine metrics for clipping, and three of ten metrics for adhesiolysis discriminated between experience levels. Time and motion path length were significant on all four tasks. We used the validated individual metrics to create summary equations for each task, which successfully distinguished between the different experience levels.

Conclusion

Educators should maintain some skepticism when reviewing the plethora of metrics captured by computer-based simulators, as some but not all are valid. We showed the construct validity of a limited number of individual metrics and developed summary metrics for the LapVR. The summary metrics provide a succinct way of assessing skill with a single metric for each task, but require further validation.