Radioimmunometric determination of histamine in myeloproliferative syndromes

Quantitative analysis of histamine is increasingly used in clinical haematology. The present study demonstrates the properties of and potential indication for a novel histamine radioimmunoassay (RIA) in clinical haematology. The sensitivity of this test assay corresponds to a histamine level of 0.1 to 0.5 nM, the non-specific cross reaction with endogenous histamine metabolites appears to be less than 0.1%. The total histamine levels in the peripheral blood of healthy donors (n = 10) ranged from 10 to 100 ng/ml, the plasma histamine values from 0.02 to 0.6 ng/ml blood. Increased levels of total histamine were measured in myeloproliferative syndromes, i.e. in patients with chronic myeloid leukemia (CML) (8 of 9), myelofibrosis (OMS) (2 of 4), and polycythaemia vera (PCV) (1 of 2). An excessive increase in total histamine was observed in healthy rhesus monkeys (n = 10) treated with recombinant human interleukin-3 (rhIL-3). The total histamine value correlated with the absolute number of circulating blood basophils (correlation coefficient: 0.9). The calculated content of histamine per basophil was found to be 0.5 to 1.5 pg. Plasma histamine values in patients suffering from myeloproliferative syndromes were within the normal range. In contrast, a moderate to marked increase in plasma histamine values was observed in monkeys during IL-3 treatment. The radioimmunometric analysis of histamine clearly represents a useful new test system in clinical haematology, especially in the follow up of malignant as well as IL-3-induced myeloproliferation.     

Posttraining presentation of a flashing light alters retrieval of a two-way active avoidance task in rats.

Rats were trained and tested in a two-way active avoidance task (30 trials, 0.4-mA footshock, 24-h training-test interval). Exposure to an open field with flashing light (60-W lamp, 30 Hz, for 7 min, OFL) 2 h after training caused a retrieval impairment for the avoidance task, a phenomenon called retroactive interference. Animals familiarized with the OFL 24 h before training showed no retrieval impairment when exposed to the OFL 2 h after training. Both adrenal medullectomy (performed 7 to 14 days before training) and dexamethasone treatment (2 mg/kg, injected IP 24 h and 12 h before training) prevented the OFL interfering effect. Time-course experiments revealed that OFL presented either 1 or 4 h after training caused no retrieval deficit, and that animals exposed to the OFL 2 h after training and receiving another OFL presentation 1 or 2 h, but not 4 h, prior to testing had normal retrieval performance. These results suggest: 1) that the retroactive interference caused by presentation of OFL 2 h after training is due to failure of retrieval of the avoidance task since it is counteracted by the pretest presentation to the OFL, 2) that the OFL-induced retrieval interfering effect partly depends on the novelty of the OFL situation, and on the functional integrity of pituitary ACTH and adrenomedullar-dependent mechanisms and 3) that there are different mechanisms involved in posttraining and pretest OFL effects since they present distinct time-courses.     

IgA cross-reactivity between a nuclear autoantigen and wheat proteins suggests molecular mimicry as a possible pathomechanism in celiac disease

Celiac disease patients display IgA antibody reactivity to wheat as well as to human proteins. We used serum IgA from celiac patients and, for control purposes, from patients with Crohn's disease, ulcerative colitis and from healthy individuals to identify celiac disease-specific IgA autoantigens in nitrocellulose-blotted extracts from various human cell types (epithelial, endothelial, intestinal cells, fibroblasts). The pattern, recognition intensity and time course of IgA autoreactivity was monitored using serial serum samples obtained from celiac children before and under gluten-free diet. By immunoblot inhibition and subcellular (cytosolic, nuclear) cell fractionation we identified a 55 kDa nuclear autoantigen expressed in intestinal, endothelial cells and in fibroblasts which was recognized by IgA antibodies of approximately half of the celiac disease patients and cross-reacted with wheat proteins. IgA reactivity to the 55 kDa autoantigen disappeared during gluten-free diet and was inhibited after pre-absorption of sera with wheat proteins but not with tissue transglutaminase, previously reported as the unique celiac disease-specific autoantigen. In conclusion, we defined a novel 55 kDa celiac disease-specific nuclear IgA autoantigen which shares epitopes with wheat proteins and which is different from tissue transglutaminase and calreticulin. Although the newly defined autoantigen was recognized much less frequently than tissue transglutaminase, our data suggest molecular mimicry between wheat and human proteins as a possible pathomechanism for the induction and/or maintenance of mucosal tissue damage in celiac disease.     

Serum tryptase levels in patients with mastocytosis: correlation with mast cell burden and implication for defining the category of disease

BACKGROUND: The serum tryptase level is used as a diagnostic marker in mastocytosis and is considered to reflect the burden of (neoplastic) mast cells (MC). METHODS: In the present study, serum tryptase levels were measured in patients with mastocytosis by fluoroenzyme immunoassay and compared with the extent of infiltration of the bone marrow (BM) by neoplastic MC, determined by tryptase immunohistochemistry. Sixteen patients with cutaneous mastocytosis (CM) and 43 patients with systemic mastocytosis (SM) were examined. RESULTS: In most patients with CM (defined by the absence of dense compact MC infiltrates in tryptase-stained BM sections), normal or near-normal serum tryptase levels (median 10 ng/ml, range 2-23 ng/ml) were measured. By contrast, in the vast majority of patients with SM, elevated serum tryptase levels (median 67 ng/ml) were found. In addition, there was a significant correlation between the grade of infiltration of the BM by neoplastic MC and tryptase levels in patients with SM (r = 0.8). Moreover, enzyme levels differed significantly among the groups of patients with different types of SM. The highest levels (>900 ng/ml) were detected in the patient with MC leukemia, 2 patients with slowly progressing SM and high MC burden (smoldering SM) and 1 patient with indolent SM. In contrast, in all 3 patients with isolated BM mastocytosis (no skin lesions and no signs of multiorgan involvement), serum tryptase levels were <20 ng/ml. CONCLUSIONS: In summary, our data suggest that the measurement of serum tryptase is a reliable noninvasive diagnostic approach to estimate the burden of MC in patients with mastocytosis and to distinguish between categories of disease.     

Alternative pathways of MYCN gene copy number increase in primary neuroblastoma tumors

Neuroblastomas, tumors of the sympathetic nervous system, account for 7-10% of the cancers of childhood. Genetic studies have shown, and this study has confirmed, that neuroblastomas are very heterogeneous; no single genetic change common to all neuroblastomas has yet been identified. One genetic aberration found frequently in this pediatric tumor is MYCN gene amplification. Recently we identified a new subset of tumors showing MYCN gain (small increases in gene number arising from unbalanced translocation). To investigate whether gain precedes amplification or is an independent event, we surveyed 200 primary tumors for MYCN copy number with fluorescence in situ hybridization; 152 of 200 (76%) were MYCN single-copy tumors, whereas 48 of 200 (24%) tumors harbored MYCN abnormalities: 36 of the 48 (75%) had MYCN amplification and 12 (25%) had MYCN gain. Among the 36 with MYCN amplified gene, we found four that also showed gain. In three tumors exhibiting simultaneous gain and amplification, these two events were detected in neighboring cells. In the fourth case we detected only MYCN gain in metastatic neuroblasts in the bone marrow, but both MYCN amplification and gain in the primary tumor. The detailed study of these four cases suggests that there may be several different mechanisms leading to increase in MYCN copy number. Further studies in other human malignancies are necessary to determine whether simultaneous gain and amplification are specific to neuroblastoma or constitute a general mechanism by which tumor cells can acquire selective growth advantage.     

Spectrum of associated clonal hematologic non-mast cell lineage disorders occurring in patients with systemic mastocytosis

Systemic mastocytosis (SM) is a myeloproliferative disease affecting multipotent and/or mast cell-committed hematopoietic progenitor cells. In a significant subgroup of patients (10-35%), an associated clonal hematologic non-mast cell lineage disorder (AHNMD) occurs. These AHNMDs can be classified according to recently established WHO criteria. Most AHNMDs resemble myeloid malignancies such as acute myeloid leukemia, myeloproliferative disorders or myelodysplastic syndromes. In only a few cases, lymphoproliferative disorders are diagnosed. Patients with SM-AHNMD have a less favorable prognosis concerning survival when compared to indolent SM. No general guidelines for the treatment of patients with SM-AHNMD have been established so far. A reasonable straightforward approach may be to treat the AHNMD in those patients in the same way as if no coexisting SM exists.