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Notes: Proliferation centres, also known as pseudofollicles, are present in approximately 90% of lymphocytic lymphomas (B-CLL). They consist of loosely arranged larger cells that often contain prominent nucleoli. In contrast to true B-cell follicles, which may be found entrapped within the small lymphocytic infiltrate in sections of B-CLL, proliferation centres are said not to contain follicular dendritic cells, although their presence has been occasionally recorded. We have carried out an immunohistochemical study of proliferation centres from 30 lymph node specimens of known cases of B-CLL, classified according to the Kiel classification, in six of which fresh frozen in addition to paraffin embedded tissue was available. We have compared proliferation centres with the surrounding small lymphocytic infiltrate and reactive B-cell follicles with respect to the presence of follicular dendritic cells and their associated network of IgM and complement, the cell proliferation fraction, the concentration of T-cells and the expression of bcl-2 protein. Most proliferation centres contained a delicate follicular dendritic cell network which was associated with IgM and complement, and showed a higher proliferation fraction than the surrounding small lymphocytic infiltrate. The proliferation centres contained more T-cells than the surrounding infiltrate and showed decreased expression of bcl-2 protein. Entrapped reactive B-cell follicles contained a much denser network of follicular dendritic cells, associated with much stronger expression of IgM and complement, and exhibited a very high proliferation fraction; they contained many T-cells and expressed very little bcl-2 protein. These results show that proliferation centres share many properties with reactive B-cell follicles and suggest that they may be centres of antigen driven proliferation.

Notes: Lung calcification was detected in four out of 29 long-term dialysed patients on whom postmortem examinations were performed between 1967 and 1980. On light microscopy, calcification showed either a finely granular and linear localization along the alveolar septa, or a coarse and widespread parenchymal distribution. Histochemical studies revealed evidence of calcium, magnesium and phosphate ions in the deposits. Ultrastructural examination of the less severely involved alveolar septa showed selective deposition of calcium salts within an increased amount of elastin. The deposits consisted of electron dense roundish granules with a concentric laminar structure. They appeared either single or conglomerated in polycyclic formations, supposedly representing the progressive steps of the mineralization process, at first localized within elastin and progressively spreading outside it. The high magnesium content of the deposits suggests that the serum concentration of this ion may play an important role in visceral calcification of longterm dialysed patients.

Notes: We describe the clinical presentation, morphology, immunophenotypic features and molecular biology of seven cases of conjunctival lymphoid infiltration. In five cases there was either immunophenotypic or molecular evidence of B-cell lymphoma. Each of these cases showed the morphological, immunophenotypic and molecular feature of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. The findings suggest that most conjunctival lymphomas are of this type and explains their uniformly favourable prognosis.

Notes: Functional dendritic cells (DC) are professional antigen-presenting cells (APC) and can be generated in vitro from healthy as well as from leukaemic cells from acute myeloid leukemia (AML) patients giving rise to APC of leukaemic origin-presenting leukaemic antigens. We describe the generation and characterization of DC from different mononuclear cell (MNC) fractions from 50 AML patients under different serum-free culture conditions, determine the optimal culture conditions and compare the results with that from 23 healthy donors. In parallel cultures, we compared DC harvests after 7- or 14-day culture, with total or adherent MNC or T-cell depleted MNC or peripheral blood (PB) or bone marrow-MNC (BM–MNC), thawn or fresh MNC, in Xvivo or CellGro serum-free media, ±10% autologous plasma or ±FL. In detail, we could show that AML–DC harvests were higher after 10–14 days culture (healthy DC: 7 days); total or adherent PB or BM–MNC fractions yield comparable DC counts, however, from magnetic cell sorting (MACS)-depleted MNC fractions or thawn MNC lower DC counts can be generated. Whereas the addition of FL increases the DC harvest, the addition of autologous plasma in many cases has inhibitory influence on DC maturation. CellGro and Xvivo media yield comparable DC counts. Optimal harvest of vital and mature DC from AML samples was obtained with a granulocyte/macrophage-colony stimulating factor, interleukin-4, FL and tumour necrosis factor-α-containing serum-free Xvivo medium after 10–14 days of culture (36/26% DC; 38/64% vital DC; 46/51% mature DC were generated from AML/healthy MNC samples). Surface marker profiles (e.g. costimulatory antigen expressing) of DC obtained from AML samples were comparable with that of healthy DC. The leukaemic derivation of AML–DC was demonstrated by the persistence of the clonal cytogenetic aberration in the DC or by coexpression of leukaemic antigens on DC. Autologous T-cell activation of leukaemia-derived DC was demonstrated in cases with AML. Autologous T cells proliferate and upregulate DC-contact-relevant antigens. We demonstrate that the generation of leukaemia-derived DC is feasable in AML under serum-free culture conditions giving rise to DC with comparable characteristics as healthy DC and offering an anti-leukaemia-directed immunotherapeutical vaccination strategy in AML.

Notes: Functional dendritic cells (DC) are professional antigen-presenting cells (APC) and can be generated in vitro from healthy as well as from leukaemic cells from AML patients giving rise to APC of leukaemic origin presenting leukaemic antigens. In a comparative methodological analysis of 50 AML samples, we could already show that leukaemia-derived DC can regularly be generated under serum-free culture conditions. In this study, we describe the generation and characterization of DC from different mononuclear cell (MNC) fractions from 24 myelodysplastic syndrome (MDS) patients under those different serum-free culture conditions, determine the optimal culture conditions and compare the results with that from 23 healthy donors. In parallel cultures, we compared DC harvests after 7- or 14-day culture, with total or adherent MNC or T-cell-depleted MNC or PB or BM–MNC, thawn or fresh MNC, in Xvivo or CellGro serum-free media, ±10% autologous plasma or ±FL. In detail, we could show that MDS–DC harvests compared to healthy DC were higher after 10- to 14-day culture; total or adherent PB or BM–MNC fractions yield comparable DC counts; however, from MACS-depleted MNC fractions or thawn MNC lower DC counts can be generated. Whereas the addition of FL increases the DC harvest, the addition of autologous plasma in many cases has inhibitory influence on DC maturation, CellGro and Xvivo media yield comparable DC counts. Optimal harvest of vital and mature DC from MDS samples was obtained with a GM-CSF, IL-4, FL and TNF-α containing serum-free Xvivo medium after 10–14 days of culture (18/26% DC; 54/64% vital DC; 59/51% mature DC were generated from MDS/healthy MNC samples). Surface marker profiles (e.g. costimulatory antigen expression) of DC obtained from MDS samples were comparable with that of healthy DC. The leukaemic derivation of MDS–DC was demonstrated by the persistence of the clonal cytogenetic aberration in the DC or by coexpression of leukaemic antigens on DC. Autologous T-cell activation of leukaemia-derived DC was demonstrated in cases with MDS. Autologous T cells proliferate and upregulate DC-contact-relevant antigens. We are the first who demonstrate that the generation of leukaemia-derived DC is feasible not only in AML but also in MDS under serum-free culture conditions giving rise to DC with comparable characteristics as healthy DC and offering an antileukaemia-directed immunotherapeutical vaccination strategy in AML and MDS.

Notes: We present a 27-year-old woman with non-systemic diffuse lymphangiomatosis of spleen and liver. The tumour consisted of capillary and cavernous lymphatic vessels located in abundant fibrous tissue. The vascular endothelium showed immunoreactivity for factor VIII-related antigen. A basal lamina could be demonstrated immunohistochemically and by electronmicroscopy.

Notes: Spindle cell haemangioendothelioma is an uncommon vascular lesion, of which 35 cases have been previously reported. A further 20 cases are reported herein. These lesions affected a wide age range in both sexes, and showed a predilection for the extremities. Twelve patients had multiple lesions and, in these cases, local progression over many years but no true recurrence was typical. None of the 20 patients developed metastases. but one later developed an angiosarcoma. Individual cases were associated with congenital lymphoedema, Klippel-Trenaunay syndrome and early-onset varicose veins.Histologically, in addition to the admixture of cavernous spaces and solid spindle cell/epithelioid cell areas, the presence both of irregularly distributed and perivascular smooth muscle cells and of malformed variably-sized vessels at the periphery of almost every lesion was noted in each case. Reticulin staining, immunohistochemistry and electronmicroscopy revealed the presence of primitive vessel formation and partial endothelial differentiation in the solid spindle cell areas. Combining these data with those from previously published series, it is suggested that spindle cell haemangioendothelioma is a non-neoplastic lesion (rather than a borderline malignancy as it is currently regarded) and that its development correlates with histological and/or clinical evidence of a malformed vasculature at the affected site.

Notes: We describe two patients with low-grade and one patient with mixed low- and high-grade B-cell lymphoma of mucosa associated lymphoid tissue (MALT) type arising in the large intestine. In each patient the lesion occurred as a single polyp. Two patients presented with rectal bleeding and in one the lesion was discovered incidentally. The bone marrow was uninvolved in all three cases but in the patient with mixed low- and high-grade lymphoma involvement of mesenteric lymph nodes and liver was found. CT scan revealed no lymphadenopathy or splenomegaly in any of the patients. Two patients remain well 9 and 24 months respectively after polypectomy whereas the patient with mixed low- and high-grade lymphoma died 7 days after hemicolectomy due to cardiac failure. These previously undescribed solitary polypoid MALT lymphomas can closely resemble both benign lymphoid polyposis of the colon and lymphomatous polyposis (mantle cell lymphoma). Because of their different behaviour accurate diagnosis of polypoid MALT lymphoma is important.