Antibodies specific for gp40 inhibit cell‐cell adhesion by cross‐linking the protein on the surface of Dictyostelium purpureum

Abstract

We have previously suggested a role for gp40 in cell-cell adhesion in Dictyostelium purpureum from the fact that antibodies specific for this protein inhibited adhesion in an in vitro assay [Springer: Dev Biol 133:447-455, 1989]. To further confirm the role mutants lacking the protein were isolated and characterized. To our surprise, the mutants had normal adhesive properties both in vitro and in situ. These results lead us to the conclusion that gp40 is not necessary for the cell-cell adhesions observed and may not be a molecule which directly participates in these adhesions. When studied further, we found that adhesion-inhibitory antibodies were only effective as divalent IgG. Monovalent Fab fragments of the same antibodies could not inhibit adhesion. The inhibitory antibodies also caused the cells to remain rounded and incapable of attaching to plastic surfaces. We conclude that when divalent antibodies specific for gp40 cross-link this protein on the cell surface a cytoskeletal change prevents them from attaching to substratum as well as to other cells, thereby inhibiting cell-cell adhesion. We suggest that an alternative mechanism for inhibition of cell-cell adhesion by divalent antibodies exists and should be considered before proposing a direct role for a protein in adhesion.

Characterization and Endocytic Internalization of Epith-2 Cell Surface Glycoprotein during the Epithelial-to-Mesenchymal Transition in Sea Urchin Embryos

“…Although relevance of using intact divalent Abs against cell surface proteins in attempt to inhibit cell–cell adhesion is not generalized (43), consistent with previous reports (44–46), the present mAb utilization apparently worked. Thus, regardless whether the Ab is applied as an intact divalent form or a monovalent form, the validity would be dependent on their molecular property in antigen/Ab interaction.…”

Keratinocytes Store the Antimicrobial Peptide Cathelicidin in Lamellar Bodies

“…Blocks hardened within 15 min and sections were collected on 1% parlodion-coated nickel grids. Immunogold labeling was performed as previously described (Deftos et al, 1993;Springer and Haywood-Reid, 1993), using a 1:5 dilution of polyclonal rabbit antihCAP18/LL-37 antibody and goat anti-rabbit IgG conjugated to colloidal gold. Rabbit pre-immune serum served as a negative control.…”

Fibroblast senescence in pressure ulcers

“…Samples for colloidal gold immunohistochemistry were processed by a modification of the method described by Springer and Haywood-Reid . 15 Briefly, tis sue blocks were fixed in 3% paraformaldehyde and 0.5% glutaraldehyde in 0.1 M sodium cacodylate buffer, pH 7.4, overnight at 4°C followed by incubation for 10 minutes at room temperature in 100-mM glycine in cacodylate buffer. Samples were then dehydrated with graded ethanol solutions ending with 70% ethanol.…”

“…Immunostaining was done as described previously. 15 Sections of LR White embedded tissues were picked up on parlodian coated nickel grids. After a 30-minute incubation in 50 mM Tris-HCL, 150 mM NaCl, pH 7.6, containing 5% normal goat serum, 0.8% BSA, WOUND REPAIR AND REGENERATION JANUARY-FEBRUARY 7998 0.1% cold water fish gelatin, and 0.02% Na Azide to block nonspecific binding, grids were transferred to the same buffer without goat serum (wash buffer) containing a 1:100 dilution of monoclonal antibody to terminin 14 and incubated for 2 hours at room temperature.…”