Juha Pekka Turunen

In vitro experimental studies of sialyl Lewis x and sialyl Lewis a on endothelial and carcinoma cells: crucial glycans on selectin ligands

Extravasation from the blood of malignant tumour cells that form metastasis and leukocytes that go into tissues require contact between selectins and their sialyl Lewis x and sialyl Lewis a (sLex and sLea respectively) decorated ligands. Endothelial cells have been shown to express sLex epitopes in lymph nodes and at sites of inflammation, and this is crucial for the selectin-dependent leukocyte traffic. Besides the ability to synthesize sLex on sialylated N-acetyllactosamine via the action of α(1,3)fucosyltransferase(s), endothelial cells can also degrade sLex to Lewis x through the action of α(2,3)sialidase(s). In addition, several epithelial tumors possess the machinery to synthesize sLex, which facilitates their adhesion to endothelial E- and P-selectin.

Evidence that lymphocyte traffic into rejecting cardiac allografts is CD11a- and CD49d-dependent.

Acute cardiac allograft rejection is characterized by infiltration of leukocytes into tissue parenchyma, but the site of entry and endothelial adhesion molecules involved are not yet defined. Lymphocyte binding to frozen sections prepared from day-3 rejecting cardiac allografts was significantly increased compared with sections made from normal hearts (number of bound lymphocytes, 983±216 per mm2 vs. 309±121, respectively, P<0.001) or syngeneic grafts. The bound lymphocytes were located exclusively only on the top of the capillary structures and not on any other sites on the heart vasculature. We further wanted to analyze which of the cloned endothelial adhesion molecules and their counterreceptors would be involved in the increased lymphocyte binding. Lymphocyte pretreatment with

Adhesion molecules involved in protein kinase A- and C-dependent lymphocyte adherence to microvascular endothelial cells.

A twofold increase in lymphocyte adherence to rat microvascular endothelial cells (EC) was achieved by incubating EC for 4 h with IL‐1α or dibulyryl‐cAMP (stimulators of protein kinase A, PKA) and PMA (stimulator of protein kinase C, PKC). Monoclonal antibodies anti‐CD11a, anti‐CD18 (LFA‐I) and anti‐CD49d (VLA‐4α) significantly inhibited the increased lymphocyte binding to IL‐lα‐induced EC, anti‐CD 18 and to a lesser extent anti‐CD11a and anti‐CD49d to dibutyryl‐cAMP‐induced EC, whereas only anti‐CD11a and anti‐CD18 monoclonal antibodies inhibited PMA‐induced lymphocyte binding. These findings suggest that stimulation of PK A and PKC induces lymphocyte binding to EC via different adhesion molecules.

Site of influx of inflammatory white cells into a rejecting rat renal allograft.

In this paper we demonstrate that the vascular endothelium of a normal kidney and a syngeneic kidney graft binds only poorly syngeneic or allogeneic lymphocytes in an in vitro binding assay. On the contrary, the peritubular capillary endothelium of an allograft binds almost 7 times more lymphocytes than the peritubular capillary of a normal kidney. These findings suggest that the site of influx of inflammatory capillary white cells into the graft during rejection is the peritubular capillary endothelium.

Lymphocyte binding to and penetration through vascular endothelium is stimulated by platelet-activating factor.

Lymphocytes have an important role in acute inflammatory reactions such as acute allograft rejection. Recirculating lymphocytes attach to vascular endothelium and penetrate through it into tissue parenchyma. Many recent studies have shown that different protein mediators, like gamma interferon, interleukin 1 and tumour necrosis factor enhance lymphocyte binding to and penetration through the endothelium, i.e. lymphocyte homing. We investigated the effect of platelet‐activating factor (PAF) in lymphocyte binding and penetration in vitro. Treatment of rat heart microvascular endothelial monolayers with PAF (10−6‐10−10M) increased the lymphocyte binding up to 1,6‐fold. The effect is dose‐ and time‐dependent. The PAF effect was reversible upon removal of the agonist: 60 min after removal of PAF no increase in the lymphocyte binding was detected. Pretreatment of endothelial cells, lymphocytes, or both of these cell types led to an increase in lymphocyte binding to endothelial monolayers. The effect of PAF in lymphocyte penetration through endothelium was investigated by using endothelial cell monolayers cultured on top of millipore filters. An optimal PAF dose (10−8 M) for 10 min increased the number of lymphocytes penetrating through the endothelial cell monolayer into the filter by a factor of 3. These results suggest that PAF has no important role in lymphocyte homing, since it can activate the endothelial cells, the lymphocytes, or both cell types.

Cellular characteristics of non-allergic eosinophilic conjunctivitis

Purpose:  This study examines the histology of conjunctival biopsy samples from patients with persistent allergic eosinophilic conjunctivitis (AEC) or non‐allergic eosinophilic conjunctivitis (NAEC).

Effect of lymphocyte activation status on binding to endothelium

When endothelial cells (EC) were stimulated with IL‐1 and/or lymphocytes with rIL‐2 or PHA, the binding of lymphocytes to EC was increased. PMA treatment of lymphocytes alone did not increase their binding to EC, but when EC were additionally induced with IL‐1 the binding was increased. The expression of LFA‐1 was constant, whilst the expression of CD49d was increased after rIL‐2 and PHA stimulation. The PMA‐ and rIL‐2‐induced lymphocyte binding to IL‐1‐induced EC was inhibited by anti‐CD11a, CD18 and CD49d mAbs; on the other hand, the enhanced binding of PHA‐stimulated lymphocytes to EC could not be blocked by these mAbs. These results show that activation of lymphocytes by various stimuli leads to different usage of adhesion pathways in their binding to inflammatory EC.