Circulating concentrations of soluble L-selectin (CD62L) in patients with primary Sjögren's syndrome

OBJECTIVE—Serum concentrations of soluble (s) L-selectin (CD62L) were measured in patients with primary Sjögren's syndrome (SS) to relate these concentrations to clinical and immunological features of SS.
METHODS—The study included 40 consecutive patients (38 women and two men) with a mean age of 61 years (range 24-78) who fulfilled four or more of the preliminary diagnostic criteria for SS proposed by the European Community Study Group in 1993, and 33 healthy blood donors from the hospital blood bank. A sandwich enzyme linked immunosorbent assay (ELISA) was used to detect the soluble form of human sL-selectin (CD62L).
RESULTS—The mean (SEM) values of sL-selectin (CD62L) were 861 (66) µg/ml for patients with SS and 986 (180) µg/ml for healthy blood donors, but there was no significant difference. In patients with primary SS, serum sL-selectin (CD62L) concentrations were significantly higher in patients with Raynaud's phenomenon (1275 (112) µg/ml versus 789 (69) µg/ml, p=0.007), autoimmune thyroiditis (1162( )(113) µg/ml versus 787 (69) µg/ml, p=0.02) and rheumatoid factor (993 (95) µg/ml versus 684 (70) µg/ml, p=0.01) when compared with patients without these features.
CONCLUSION—The presence of Raynaud's phenomenon, autoimmune thyroiditis and rheumatoid factor is associated with higher concentrations of circulating sL-selectin (CD62L) in the sera of patients with primary SS.


CD229 (Ly9) lymphocyte cell surface receptor interacts homophilically through its N-terminal domain and relocalizes to the immunological synapse

CD229 is a member of the CD150 family of the Ig superfamily expressed on T and B cells. Receptors of this family regulate cytokine production and cytotoxicity of lymphocytes and NK cells. The cytoplasmic tail of CD229 binds to SAP, a protein that is defective in X-linked lymphoproliferative syndrome. To identify the CD229 ligand, we generated a soluble Ig fusion protein containing the two N-terminal extracellular domains of human CD229 (CD229-Ig). CD229-Ig bound to CD229-transfected cells, whereas no binding was detected on cells expressing other CD150 family receptors, showing that CD229 binds homophilically. Both human and mouse CD229 interacted with itself. Domain deletion mutants showed that the N-terminal Ig-domain mediates homophilic adhesion. CD229-CD229 binding was severely compromised when the charged amino acids E27 and E29 on the predicted B-C loop and R89 on the F-G loop of the N-terminal domain were mutated to alanine. In contrast, one mutation, R44A, enhanced the homophilic interaction. Confocal microscopy image analysis revealed relocalization of CD229 to the contact area of T and B cells during Ag-dependent immune synapse formation. Thus, CD229 is its own ligand and participates in the immunological synapse

Platelet activation In mice and human Helicobacter pylori infection.

Extracts of Helicobacter pylori (HP) have been shown to induce leukocyte adhesion in mesenteric venules, but the effects of HP infection on gastric microvessels are unknown. Inflammatory cell interactions in the gastric microcirculation were studied by intravital videomicroscopy in mice inoculated with either saline or fresh isolates of HP. Platelet aggregates were detected and quantified in murine portal blood, while endothelial P-selectin expression was determined using the dual radiolabeled mAb technique. Platelet activation and aggregation were studied in HP-infected patients and controls by measuring the platelet-aggregate ratio and platelet P-selectin expression. HP infection induced a marked increase in the flux of rolling leukocytes and the appearance of platelet and leukocyte- platelet aggregates in murine gastric venules. The HP-induced rolling and platelet aggregate formation was abrogated by mAbs against L- or P-, but not E- selectin. Endothelial cell expression of P-selectin was not altered, but platelet P-selectin expression was enhanced in HP-infected mice. Circulating platelet aggregates and activated platelets were also detected in HP-infected patients. These findings indicate that platelet activation and aggregation contribute to the microvascular dysfunction and inflammatory cell recruitment associated with HP infections