An oral challenge test with carmine red (E120) in skin prick test positive patients.

BACKGROUND: Positive skin prick test reactions to carmine red (E120) occur in approximately 3% of the patients studied for food allergy. Carmine ingestion associated systemic symptoms are occasionally suspected, but sufficient information of proven carmine allergy is not available. PATIENTS AND METHODS: To analyse carmine related symptoms in skin prick test positive patients a cohort of 23 patients with suspected allergy to carmine red was subjected to a single-blind placebo-controlled oral challenge test with carmine red. RESULTS: Five patients developed clinical symptoms during the placebo-controlled oral challenge. As a result, the overall frequency of clinical carmine allergy is estimated to be 0.7% in general dermatology patients studied for food-associated symptoms. CONCLUSIONS: Oral challenge test provides a valuable in vivo tool to better inform patients with positive skin prick tests to additives to avoid false allergy diets.

Both normal and leukemic B lymphocytes express multiple isoforms of the human Aiolos gene.

Aiolos is a chromatin remodeling transcription regulator that plays an antiproliferative role in B lymphocyte function. In contrast to the related Ikaros factors, mammalian Aiolos has not been reported to generate splice variants. In addition, although human leukemic lymphoblasts express non-DNA-binding Ikaros isoforms with potential dominant negative effect on other interacting factors,the role of Aiolos in human lymphoid disorders has remained obscure. To address the question, why Aiolos should delineate from Ikaros in such a marked way, we have here analyzed whether also human Aiolos could generate alternate isoforms. According to the results obtained, both normal and neoplastic B lineage cells were found to express at least five novel Aiolos variants. Also structurally dominant negative variants with less than three DNA-binding domains were identified. In conclusion, given the multiplicity of also human Aiolos isoforms and thereby the evidently more intricate contribution of Aiolos to the chromatin remodeling machinery, it is suggested, that not only Ikaros, but also Aiolos could participate in a more versatile manner in the regulation of B lymphocyte function.

Pax-5 and EBF are expressed in committed B-cell progenitors prior to the colonization of the embryonic bursa of fabricius.

The committed B-cell precursors developing from hemopoietic stem cells have been considered to differentiate through a common lymphoid progenitor stage in the mouse. In the chicken B-cell system, however, the committed B-cell progenitors burst as a single wave prior to the bursal colonization and most likely as direct descendants of hemopoietic stem cells. In the present report we show that prebursally committed B-cell progenitors specifically express early B-cell factor (EBF) and Pax-5 transcription factors. In addition we show that the expression of these and other B-lineage-associated transcription factors starts early in the chicken ontogeny. Altogether our findings strongly support the model of early delineation of B- and T-cell development and do not support the existence of common lymphoid stem cells.

Prethymic progenitors from the avian para-aortic mesoderm express GATA-3 and distinct chTcf isoforms but still lack T-cell receptor-gamma rearrangements.

Haematopoietic precursors first colonizing the avian embryonic thymus are derived from the intraembryonic sites located around the dorsal aortae. These intraembryonic precursors have previously been demonstrated to include cells that harbour T-cell progenitor capacity and express the Ikaros transcription factor, known to be a prerequisite for lymphocyte development. In this study, we further evaluated the properties of these prethymic cells. We show that early intraembryonic cells and prethymic progenitors already express the GATA-3 transcription factor. The chicken homologue of T-cell factor-1, chTcf, is also detected in cells isolated from the avian para-aortic region. However, these intraembryonic cells retain their T-cell receptor gamma loci in germline configuration. Interestingly, chTcf was found to express different alternatively spliced isoforms during early ontogeny and thymic T-cell development, which indicates developmentally regulated expression of chTcf variants. Taken together, these results demonstrate that, although the avian prethymic progenitor cells express T-lineage-associated transcription factors, they have not yet undergone TCR rearrangements. It is therefore suggested that activation of lineage-associated genes is an early event in the generation of haematopoietic progenitor cells during ontogeny.

The evolutionarily conserved avian Aiolos gene encodes alternative isoforms.

Aiolos is an Ikaros-related lymphoid regulatory protein involved in B cell development and function. To evaluate the role of Aiolos in avian B lymphopoiesis, we have cloned and characterized the first non-mammalian Aiolos ortholog in the avian. In sharp contrast to the avian Ikaros, expressed already at the multipotential stage and prior to the colonization of the lymphoid rudiments, Aiolos transcripts were not expressed in early ontogeny and were first detected in cells isolated from the embryonic bursa of Fabricius and thymus. In accordance with Ikaros, the avian Aiolos is also highly related to the mammalian homolog, thus suggesting an evolutionarily conserved function in lymphocyte development. Interestingly, in contrast to the mammalian Aiolos, at least one alternatively spliced form of avian Aiolos is detected in addition to the primary full-length transcript. Both of these alternate transcripts are expressed in bursa, thymus and peripheral lymphoid cells, and no major differences in the expression were detected during lymphocyte development. Furthermore, avian Aiolos is clearly expressed at various stages of B cell development, thus supporting recent evidence for the importance of Aiolos in B cell development and function.

Characterization of prethymic progenitors within the chicken embryo.

The thymic primordium in both birds and mammals is first colonized by cells emerging from the intra-embryonic mesenchyme but the nature of these precursors is poorly understood. We demonstrate here an early embryonic day 7 prethymic population with T lymphoid potential. Our work is a phenotypic analysis of, to date, the earliest embryonic prethymic progenitors arising in the avian para-aortic area during ontogeny. The phenotype of these cells, expressing the cell surface molecules alpha2beta1 integrin, c-kit, thrombomucin/MEP21, HEMCAM and chL12, reflects functional properties required for cell adhesion, migration and growth factor responsiveness. Importantly, the presence of these antigens was found to correlate with the recolonization of the recipient thymus following intrathymic cell transfers. These intra-embryonic cells were also found to express the Ikaros transcription factor, the molecular function of which is considered to be prerequisite for embryonic lymphoid development.

Expression of chL12 surface antigen is associated with cell survival in the avian bursa of Fabricius.

During B-cell development in the avian bursa of Fabricius most of the developing B cells die by apoptosis and only a minority survive to emigrate into the periphery. Recently, it has been shown that when developing bursal cells become mature and ready to migrate they start to express chL12 antigen. The expression of this cell-surface molecule was found to be associated with the survival of the bursal cells both after in vitro culture and after in vivo cyclophosphamide (CY) treatment. The frequency of early apoptotic cells in freshly isolated bursal cells was found to be high. The high susceptibility of these cells to apoptosis is in line with the finding of low bcl-2 mRNA expression. We conclude that expression of avian chL12 antigen is associated with the survival of bursal cells.

Avian Ikaros gene is expressed early in embryogenesis.

Ikaros transcription factors dictate the key steps in lymphoid lineage determination. To reveal the evolutionary aspects of regulatory molecules involved in early lymphocyte development, we studied the cDNA of the avian Ikaros homolog. We demonstrate here that the Ikaros gene is highly conserved across avian and mammalian species. Importantly, the Ikaros mRNA is already expressed in early chicken embryos, from embryonic day 2 onwards, thus markedly before the traffic of the first precursor cells to the lymphoid primordia, thymus and the bursa of Fabricius. We suggest that the embryonic expression of the Ikaros transcripts represents an early onset of lymphoid differentiation.