Peter Bucsky

Contemporary classification of histiocytic disorders

Pathologists and pediatric hematologist/ oncologists of the World Health Organizations Committee on Histiocytic/Reticulum Cell Proliferations and the Reclassification Working Group of the Histiocyte Society present a classification of the histiocytic disorders that primarily affect children. Nosology, based on the lineage of lesional cells and biological behavior, is related to the ontogeny of histiocytes (macrophages and dendritic cells of the immune system). Dendritic cell-related disorders of varied biological behavior are dominated by Langerhans cell histiocytosis, but separate secondary proliferations of dendritic cells must be differentiated. Juvenile xanthogranuloma represents a disorder of dermal dendrocytes, another dendritic cell of skin. The hemophagocytic syndromes are the most common of the macrophage-related disorders of varied biological behavior. Guidelines for distinguishing the exceedingly rare malignant diseases of histiocytes from large cell lymphomas through the use of a battery of special studies are provided.

Enhanced Interleukin-6 and Interleukin-8 Synthesis in Term and Preterm Infants

There is growing evidence that sepsis-related complications in neonates are crucially mediated by the action of proinflammatory cytokines. It has previously been demonstrated that elevated IL-6 and IL-8 levels can predict brain damage and chronic lung disease in preterm infants. However, it is the current view that neonates have a reduced capability to produce proinflammatory cytokines. To clarify this issue, we analyzed the inflammatory response in term and preterm infants directly at the single cell level by flow cytometry. Endotoxin challenge was performed under defined conditions on monocytes obtained from 50 healthy adults and 119 neonates, which consist of 45 term infants, 63 preterm infants (26.1–36.7 wk of gestational age), and 11 preterm infants with proven infection (24.6–29.9 wk). Our results challenge the existing view of an immature inflammatory response by demonstrating that term infants and preterm infants display a higher percentage of IL-6– and IL-8–positive cells than adults. After preincubation with dexamethasone the number of cytokine-positive cells decreased in all groups, but the number of IL-8–positive cells remained higher in term and preterm infants >32 wk compared with adults. These observations demonstrate not only a well-developed but also an enhanced inflammatory response in term and preterm infants. Under consideration of several detrimental effects of IL-6 and IL-8, our data may have major implications on the pathophysiology of inflammatory-triggered neonatal diseases.

Immature anti-inflammatory response in neonates

The inflammatory response plays a major role in the induction of several neonatal diseases. We hypothesize that an imbalance between the pro‐ and anti‐inflammatory response is crucial for the previously shown enhanced production of proinflammatory cytokines in term and preterm infants during infection. To test this hypothesis, we compared the capacity to produce the main anti‐inflammatory cytokines IL‐10 and TGF‐β in term infants, preterm infants and adults at different levels of synthesis by quantitative real time reverse‐transcribed PCR, flow cytometry, as well as enzyme‐linked immunoassay. Term and preterm infants showed a profoundly diminished IL‐10 mRNA‐expression and IL‐10 production after stimulation. In addition, the amount of TGF‐β‐positive lymphocytes was significantly less in neonates than adults. Furthermore, there was a considerably lower inhibition of production of IL‐1α, IL‐6, IL‐8 and TNF‐α by the use of recombinant IL‐10 in term and preterm infants compared with adults. These results demonstrate not only a diminished anti‐inflammatory capacity but also a reduced response to anti‐inflammatory stimuli in term and preterm infants. From these data we conclude that neonates display an immature compensatory anti‐inflammatory response syndrome (CARS) which may predispose preterm infants to harmful effects of proinflammatory cytokines resulting in severe organ sequelae during infection.

Differential Maturation of the Innate Immune Response in Human Fetuses

Newborns and especially preterm infants show a unique susceptibility to severe bacterial infections that cause significant morbidity and mortality. As very few data are available on innate immune functions in human fetuses, we conducted a comprehensive study to investigate the expression of several adhesion molecules essentially involved in migration (CD11a, CD11b, CD11c, CD18, and CD62L). Furthermore, phagocytic activity, generation of respiratory burst products, and production of several proinflammatory cytokines were assessed. Various functions of the fetal innate immune system were demonstrated to be essentially different from those observed in term neonates or adults. Expression of several surface markers was significantly diminished on fetal granulocytes. Furthermore, a significantly reduced phagocytic activity of fetal granulocytes and monocytes was found, contrasted by an enhanced generation of reactive oxygen products. In addition, we demonstrate that significant numbers of fetal monocytes are capable of the production of proinflammatory cytokines in response to stimulation. However, the pattern of cytokine production is different from the more mature individuals: the number of IL-6 – and tumor necrosis factor-α–positive monocytes were significantly diminished, whereas more IL-8 –producing monocytes were found compared with adults. The results of our study add significantly to our understanding of the maturation and impairment of the innate immune response.

Maturational Changes of Lymphocyte Surface Antigens in Human Blood: Comparison between Fetuses, Neonates and Adults

The objective of this study was to investigate the maturational changes of lymphocyte surface antigens during ontogeny from fetuses to adults using the proven whole blood lysis technique. Two-color flow cytometric analysis of lymphocyte surface markers was performed on 20 fetal blood samples obtained by cordocentesis, 70 cord blood and 30 adult blood samples. The leukocyte count and all T-cell subsets were highest in neonates compared to fetuses and declined into adulthood. In contrast, the percentage of CD2+ T cells (fetal blood 57% versus adult blood 82%; p ≤ 0.001), CD3+ T cells (fetal blood 52% versus adult blood 77%; p ≤ 0.001), CD4+ T cells (fetal blood 39% versus adult blood 50%; p ≤ 0.05) and CD8+ T cells (fetal blood 15% versus adult blood 24%; p ≤ 0.001) showed a significant increase from fetuses to adults. The absolute and relative amounts of B cells were highest in fetuses (fetal blood 547 × 106/l, 18%) followed by a steady decline to adulthood (adult blood 243 × 106/l, 13%; p ≤ 0.001). The discordance between the absolute and relative size of lymphocyte subpopulations emphasizes the consideration of both variables in the assessment of lymphocyte maturation. The presented data may contribute to a better knowledge of the maturation of the immune system.

Antiphospholipid Antibodies in Children without and in Adults with and without Thrombophilia

Antiphospholipid antibodies (APAs) are considered risk factors in patients with thromboembolic diseases. Although the incidence of such acquired coagulation disturbances in adults are well described, only few data exist for children. Therefore, in a first step to collect new data we analyzed the presence of different APAs in 202 consecutive children and compared them with two groups of adults. The children screened for APA were exclusively those who did not have any thromboembolic complications or a tendency for thrombophilia due to other underlying diseases such as systemic lupus or malignancy in their past or present medical history. Consecutive blood samples were evaluated from routine laboratory specimens. The two groups of adults comprised 200 patients after deep vein thrombosis and 200 patients without thromboembolic events that served as controls. Four lupus anticoagulant (LA) screening tests were determined: the dilute Russells viper venom test; a lupus anticoagulant-sensitive activated partial thromboplastin time reagent; a second lupus-sensitive activated partial thromboplastin time; and the Kaolin clotting time. Furthermore, three different antiphospholipid antibodies ELISA assays against cardiolipin (ACA), beta2-glycoprotein I, and phosphatidyl-serine, were determined. The children had a much higher prevalence for LA than did the adults. On the other hand, their values for ACA were significantly lower than in adults with a history of thromboembolism. Findings in children were similar to the normal adult group. This has to be taken into account when evaluating children with thromboembolic diseases.

Immunomodulatory Effect of Vitamin C on Intracytoplasmic Cytokine Production in Neonatal Cord Blood Cells

Background: Vitamin C (ascorbic acid) is an essential water-soluble antioxidant in cells and plasma. Besides metabolic functions, vitamin C is also known to contribute to immune homeostasis. Recently, it has been demonstrated that vitamin C has an inhibitory effect on the expression of pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) in adult whole blood cells in vitro. It has been postulated that vitamin C might be an interesting compound for modulation of an over-exuberant immune response, e.g., in patient cohorts susceptible for the development of systemic inflammatory response syndrome such as neonates. It was the aim of this study to investigate the modulatory effects of vitamin C on the production of inflammatory mediators in neonatal cord blood cells. Methods: The intracytoplasmic production of pro-inflammatory cytokines in neonatal cord blood cells stimulated with lipopolysaccharide or phorbol 12-myristate 13-acetate/ionomycin was assessed by flow-cytometry. Results: In contrast to our previous observations from adult whole blood cells, 20 mM vitamin C mildly stimulated the percentage of neonatal monocytes producing IL-6 after lipopolysaccharide stimulation (e.g., 11.3% increase compared to control, p = 0.005). In the presence of 20 mM vitamin C, even a stronger stimulatory effect was noted for the percentage of IL-8 (e.g., 46.7% increase, p < 0.001) and TNF-α producing neonatal monocytes (e.g., 69.2% increase, p = 0.004; n = 20). In accordance with adult data, the percentage of neonatal lymphocytes producing IL-2 after phorbol 12-myristate 13-acetate/ionomycin stimulation was dose-dependently reduced (e.g., 41.3% inhibition, p = 0.001, 20 mM vitamin C), while the percentage of TNF-α producing lymphocytes was mildly stimulated (e.g., 20.8% increase, p = 0.003, 20 mM vitamin C). Conclusions: Interestingly, vitamin C was demonstrated to enhance pro-inflammatory responses in CD14+ cord blood cells while only intracellular IL-2 production in CD3+ cells was diminished. These data suggest that vitamin C differentially influences intracytoplasmic cytokine production in adults and neonates, and further studies are needed to elucidate the underlying mechanisms of this selective immunomodulation.

Differentiated thyroid cancer in children and adolescents.

Introduction: There have been only a few studies on differentiated childhood thyroid cancer (DTC) in children and adolescents. Methods: We analyzed the characteristics of DTC with respect to age, gender and histology in 114 patients under 18 years of age. In a questionnaire-based survey, data of 114 patients, aged between 3 years and 18 years, was collected from 65 clinical institutions in Germany. Characteristics of 80 females and 34 males were evaluated, and the prognostic effect of age, gender, histology, multicentric growth, tumor stage and N-status on distant metastases was tested using multivariate discriminant analysis. Between-group comparison was performed using student t-test and chi-squared test. Results: The incidence of DTC in females was higher than in males with a peak of female:male ratio at puberty, which was more pronounced in children with papillary thyroid cancer, but not with follicular thyroid cancer. Papillary thyroid cancer was associated with more advanced disease (P = 0.009), more lymph-node involvement (P = 0.007) and more distant metastases (P = 0.02) compared with follicular thyroid cancer. Multivariate analysis showed advanced tumor stage as the only significant factor (P = 0.02) associating with distant metastasis. Conclusion: It can be concluded that in children and adolescents: 1. The incidence of papillary thyroid cancer is higher in females than males, with a peak at puberty. 2. The only significant factor associated with distant metastases is the advanced tumor stage. 3. Childhood thyroid cancer is frequently associated with lymph-node involvement, distant metastases and advanced tumor stage. 4. Papillary childhood thyroid cancer is more aggressive than follicular type.

Influence of Specimen Age and Use of Different Negative Controls in Determination of Intracytoplasmic Levels of Cytokines after Whole-Blood Culture Assay

ABSTRACT Intracytoplasmic detection of cytokines by flow cytometry has become a powerful tool in the characterization of cytokine-producing cells. However, it is not known to what extent specimen age and the use of various negative controls may influence the amount of cytokine-positive cells. We therefore compared different times of storage and the use of several negative controls in the determination of intracytoplasmic levels of cytokines. There was a substantial decline of interleukin-2- and gamma interferon-positive lymphocytes after 20 h and especially after 48 h of storage. The precision of intracytoplasmic interleukin-6 determination decreases after long-term storage compared to 2 h of storage, whereas the amount of interleukin-8-positive monocytes remained rather stable. Therefore, we recommend performing the analysis as fast as possible after the blood sample is drawn. Under consideration of isotype-matched antibodies and nonstimulated cells as negative controls instead of the purified antibody-blocking control, strikingly higher amounts of interleukin-2-, gamma interferon, interleukin-6-, and interleukin-8-positive cells were found. For a meaningful interpretation of data these differences have to be kept in mind. Further studies should evaluate the exact specificity of these controls.

Langerhans cell histiocytosis in children: does soluble interleukin-2-receptor correlate with both disease extent and activity?

BACKGROUND Langerhans cell histiocytosis (LCH) is characterized by monoclonal proliferation of activated Langerhans cells. Neither etiology nor pathomechanism of this disorder is presently known. However, despite monoclonality LCH might represent a reactive clonal disorder induced by immune dysfunction rather than a malignant process. To investigate a putative cytokine dysregulation in the pathogenesis of this disorder and searching for parameters of both disease activity and prognosis, serum concentrations of proinflammatory and T-cell derived cytokines were evaluated in LCH patients. MATERIALS AND METHODS Serum levels of IL-1 beta, IL-2, sIL-2R and TNF-alpha were determined by ELISA in seven children with different types of LCH: Three children (aged 6, 10 and 14 years, respectively) with single system/single bone disease; one child (11 years) with recurrent single system/multiple bone disease and three children (1, 2 and 2 years, respectively) with multisystem disease. RESULTS sIL-2R was elevated at diagnosis in seven children as compared to healthy adults (mean +/- SEM: 5,256 +/- 3,751 U/ml vs. 73 +/- 5.5 U/ml; P < 0.005) or healthy children (mean +/- SEM: 10,195 +/- 2,798 pg/ml vs. 2,638 +/- 156 pg/ml; P < 0.01). A positive correlation between serum levels of sIL-2R and extent of the disease could be observed. During remission, sIL-2R levels declined. IL-1 beta, IL-2, and TNF-alpha remained within the normal range during the study period. CONCLUSIONS Elevated sIL-2R levels seem to correlate positively with both extent and activity of LCH, thus indicating a pathological T-cell activation as a pathogenetic factor. sIL-2R level is a promising parameter to monitor disease activity in LCH and may also be of prognostic relevance.