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Migration inhibition of peritoneal macrophages by peptidoglycan
Abstract:
Previous studies have shown that peptidoglycans from group A and B streptococci inhibit the migration of peritoneal exudate cells from non-sensitized rats and guinea pigs. In the present studies peptidoglycans from S. aureus and S. epidermidis were found to inhibit the migration of cells to the same extent as group A streptococcal peptidoglycan. In contrast, HSA-pentapeptide, an immunologically active synthetic analog of the peptide moiety of peptidoglycan which is free of the intrinsic toxicity of naturally occurring peptidoglycans, did not induce migration inhibition of peritoneal exudate cells from non-sensitized guinea pigs. Sensitization of animals with 200 mug HSA-pentapeptide emulsified in incomplete Freund's adjuvant significantly reduced the inhibitory effect of streptococcal and staphylococcal peptidoglycan; HSA-pentapeptide again showed no activity. However, when HSA-pentapeptide was tested against cells from animals sensitized with 200 mug HSA-pentapeptide incorporated in complete Freund's adjuvant, a strong inhibition of migration was evident. Skin tests performed in these animals, in contrast to the dermonecrotic reaction elicited by streptococcal or staphylococcal peptidoglycan, revealed a characteristic delay hypersensitivity to HSA-pentapeptide.
Insights
Bacterial peptidoglycans inhibit immune cell migration. However, a synthetic analog, HSA-pentapeptide, induced delayed hypersensitivity in sensitized animals, unlike toxic natural peptidoglycans.
Area of Science:
- Immunology
- Microbiology
Background:
- Bacterial peptidoglycans from Streptococcus species inhibit peritoneal exudate cell migration.
- Peptidoglycans from Staphylococcus aureus and S. epidermidis also exhibit this inhibitory effect.
Purpose of the Study:
- To investigate the immunomodulatory effects of bacterial peptidoglycans and a synthetic analog, HSA-pentapeptide.
- To compare the cellular responses to natural peptidoglycans and HSA-pentapeptide in sensitized and non-sensitized animals.
Main Methods:
- Assessing the migration of peritoneal exudate cells from rats and guinea pigs.
- Utilizing natural peptidoglycans (Streptococcus, Staphylococcus) and synthetic HSA-pentapeptide.
- Employing sensitization protocols with incomplete and complete Freund's adjuvant.
- Performing skin tests to evaluate hypersensitivity reactions.
Main Results:
- Natural peptidoglycans from Streptococcus and Staphylococcus species inhibited peritoneal exudate cell migration.
- HSA-pentapeptide did not inhibit migration in non-sensitized guinea pigs.
- Sensitization with HSA-pentapeptide in complete Freund's adjuvant induced delayed hypersensitivity to HSA-pentapeptide and reduced the inhibitory effects of natural peptidoglycans.
Conclusions:
- Bacterial peptidoglycans possess intrinsic properties that inhibit immune cell migration.
- HSA-pentapeptide, a non-toxic analog, can elicit a delayed hypersensitivity response upon sensitization.
- The immune response to peptidoglycans and their analogs can be modulated by sensitization protocols.