Phagocytosis of fibronectin and collagens type I, III, and V by human gingival and periodontal ligament fibroblasts in vitro.
BACKGROUND
Electron microscopic studies have suggested that the volume density of collagen-containing vacuoles in fibroblasts is higher in the periodontal ligament (PDL) than in the gingiva. Whether this difference reflects intrinsic differences in phagocytic capacity among the cells in these tissues is not known.


METHODS
PDL and gingival fibroblasts were isolated from subjects and cultured under identical conditions in the presence of fluorescent beads coated with collagen type I, III, or V or fibronectin. Control beads were coated with bovine serum albumin or an enamel matrix protein mixture that does not constitute part of the extracellular matrix of PDL and gingiva. After various time intervals (1 to 24 hours), the percentage of cells that had internalized beads was assessed by flow cytometry. Since alkaline phosphatase activity has been suggested to play a role in collagen phagocytosis, the activity of this enzyme was determined for all cell populations.


RESULTS
The results demonstrated the following order in the percentage of cells internalizing protein-coated beads: fibronectin > collagen type I > III > V. Internalization of collagen type I-coated beads exceeded that of beads coated with bovine serum albumin or enamel matrix proteins by 6 and 3 times, respectively. No differences were observed in collagen phagocytic activity between PDL and gingival fibroblasts, and no relationship could be demonstrated between collagen phagocytosis and alkaline phosphatase activity.


CONCLUSIONS
We conclude that differences in collagen phagocytosis between PDL and gingiva, as observed in vivo, are not likely to be explained in terms of intrinsic phagocytic capacities of these cells.
van der Pauw
M T
MT
Department of Periodontology, Academic Center for Dentistry Amsterdam (ACTA), University of Amsterdam, The Netherlands.
Van den Bos
T
T
Everts
V
V
Beertsen
W
W
D008841:Actin Cytoskeleton / Q000187:drug effects; D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000032:analysis; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism*; D024061:Collagen Type III / Q000378:metabolism*; D024062:Collagen Type V / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D004247:DNA / Q000032:analysis; D003746:Dental Enamel Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D005434:Flow Cytometry; D005881:Gingiva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008854:Microscopy, Electron; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology*; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013223:Statistics as Topic
D024042:Collagen Type I; D024061:Collagen Type III; D024062:Collagen Type V; D003746:Dental Enamel Proteins; D005353:Fibronectins; D012710:Serum Albumin, Bovine; D003571:Cytochalasin B; D004247:DNA; D000469:Alkaline Phosphatase