Erythrocyte invasions and receptor heterogeneity in field isolates of Nanay river basin Iquitos

OBJECTIVE@#To determine whether the requirements for sialic acid varies and whether several types of silaic acid independent receptors utilized for invasion mechanisms of fresh filed isolates collected around Nanay river basin, Iquitos.@*METHODS@#The field isolates were cultured as described previously by Jensen and Trager and MR4 protocol with little modifications. The erythrocytes preparation and subsequent enzyme treatment was done as described previously by Sharma. with little modification. Invasion assay was performed as described previously by Sharma et al with little modification.@*RESULTS@#The Nanay river basin isolates showed five types of invasion mechanisms or types of receptors-ligand interactions. Here we observed that an equal numbers of neuraminidase sensitive and resistant invasion receptor-ligand interaction profiles as the most common receptor-ligand invasion profiles. Neuraminidase resistance trypsin sensitive chymotrypsin sensitive (NM(R)T(S)CT(S)) invasion of receptor-ligand interaction profile was found in seven isolates, Five field isolates and one reference strain showed neuraminidase sensitive, trypsin sensitive and chymotrypsin resistant (NM(S)T(S)CT(R)) invasion of receptor-ligand interactions, six isolates including one reference strains dd2 showed neuraminidase sensitive, trypsin and chymotrypsin resistance (NM(S)T(R)CT(R)) indicating its dependence on sialic acids and independence of trypsin and chymotrypsin sensitive proteins. Four isolates showed neuraminidase sensitive, trypsin sensitive and chymotrypsin sensitive (NM(S)T(S)CT(S)) invasion of receptor-ligand interactions, seven isolates were neuraminidase resistant, trypsin sensitive and chymotrypsin resistance (NM(R)T(S)CT(R)) invasion of receptor-ligand interactions, indicating its dependence on trypsin sensitive proteins.@*CONCLUSIONS@#The Nanay river basin isolates showed five types of invasion mechanisms or types of receptors-ligand interactions. A full understanding of theses invasion mechanisms may allow the development of novel prophylactic and therapeutic strategies that block erythrocyte receptor-ligand invasion mechanisms.

Functions of Siglecs in Allergic Inflammation / 소아알레르기및호흡기학회지

Siglecs are sialic acid binding Ig-like lectins, subset of the immunoglobulin superfamily. They are characterized by a homologous N-terminal V-set Ig-like domain and C2 set Ig-like domains. N-terminal domains have sialic acid binding activity. In humans, 11 Siglecs have been described sialoadhesin(Siglec-1), CD22(Siglec-2), CD33(Siglec-3), MAG(Siglec-4), more recently described CD33-related Siglecs(Siglec 5-11). Siglecs express most signal via immunoreceptor tyrosine-based inhibition motif(ITIM) cytoplasmic domains. The cytoplasmic tails of all Siglecs except sialoadhesin have one or more tyrosine residues within potential signaling motifs. Inhibitory function of other Siglecs such as Siglec-7 or Siglec-9 was shown in RBL-2H3 cells. Co-crosslinking of Siglec-7 or Siglec-9 and Fc epsilon R1 substantially reduced the serotonin release of RBL-7 and RBL-9 cells. Siglec-8 is expressed on human eosinophils, mast cells and basophils. Siglec-8 has two tyrosine motifs, a proximal motif and a distal motif. They have some inhibitory functions in immune system. We have observed that Siglec-8 is able to inhibit the IgE receptor-mediated beta-hexosaminidase release of RBL-2H3 cells following co-crosslinking. Co-crosslinking of Siglec-8 and Fc epsilon R1 reduced the hexosaminidase release of RBL-2H3 cells. These results show that Siglec-8 is as potent as Siglec-7 and Siglec-9 in delivering inhibitory signals to RBL-2H3 cells. Siglec-8 should be a new member of the inhibitory receptor superfamily and the membrane-proximal ITIM is essential for the inhibitory function of Siglec-8 molecules. Although these molecules present specific marker for the allergic cell types, more work is needed to understand the signaling mechanism and the role in various disease processes.

Expression of the ED3 Antigen and its Upregulation after Cyclophosphamide Treatment on Basal Epithelial Cells of Rat Stratified Squamous Epithelium / 대한해부학회지

Sialoadhesin (Sn) expression has been demonstrated on murine and rat macrophages in lymphatic organs and is recognized by the monoclonal antibody (mAb) ED3 in the rat. Sialoadhesin (Siglec-1), the ED3 antigen in the rat, is a subtype of sialic acid -binding Ig-like lectins (Siglecs) that bind specifically to sialic acid-containing structures such as selectins and was originally identified as the sheep erythrocyte receptor (SER) responsible for sialic acid-dependent binding of native sheep erythrocytes (SE) to resident murine bone marrow macrophages in rosetting assays. The aim of the present study was to investigate the expression and potential function of sialoadhesin in the stratified squamous epithelium of the rat tongue, esophagus and skin. The expression of sialoadhesin was demonstrated by immunohistochemical analysis with the mAb ED3. This study demonstrated not only the presence of sialoadhesin on the basal epithelial cells of the stratified epithelium in normal rat tongue, esophagus and skin but also its upregulated expression on these cells in CY-treated rats. The results of the present study shed some light on the potential function of sialoadhesin in the basal epithelial cells of the stratified epithelium. Further studies may provide more insight into the role of sialoadhesin in the epithelial stem cells.