Related Experiment Videos
Antitoxin activity of human polymorphonuclear leucocytes
Abstract:
Human polymorphonuclear leucocytes (PMNL) inactivate Clostridium difficile cytotoxin and C. perfringens phospholipase C, but not C. perfringens enterotoxin. Both whole cells and sonicated suspensions possess activity, but mononuclear cell fractions of peripheral blood do not. Antitoxin activity closely correlates with cell concentration. The highest cell concentrations tested completely inactivated C. difficile cytotoxin by 2 min. Sucrose density gradient fractionation of PMNL showed antitoxin activity to be associated with myeloperoxidase, locating it in the primary or azurophil granules. Toxin inactivation was prevented by protease inhibitors suggesting that it is due to one of the neutral proteases present in these granules. PMNL are more active against C. difficile cytotoxin than purified chymotrypsin. PMNL may be a primary defence against certain bacterial exotoxins.
Insights
Human white blood cells, polymorphonuclear leucocytes (PMNL), effectively neutralize bacterial toxins like Clostridium difficile cytotoxin. This innate immune defense mechanism involves enzymes within PMNL granules, highlighting their role in combating exotoxins.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Bacterial exotoxins pose significant health risks.
- The innate immune system, particularly white blood cells, plays a crucial role in neutralizing pathogens and their toxins.
- Polymorphonuclear leucocytes (PMNL) are key components of the innate immune response.
Purpose of the Study:
- To investigate the capacity of human polymorphonuclear leucocytes (PMNL) to inactivate specific bacterial exotoxins.
- To identify the cellular components and mechanisms responsible for PMNL's antitoxin activity.
- To determine the potential role of PMNL as a primary defense against bacterial toxins.
Main Methods:
- Incubation of PMNL (whole cells and sonicated suspensions) with Clostridium difficile cytotoxin and Clostridium perfringens toxins.
- Testing of mononuclear cell fractions for antitoxin activity.
- Sucrose density gradient fractionation of PMNL to isolate active components.
- Assessment of toxin inactivation in the presence of protease inhibitors.
- Comparison of PMNL activity with purified chymotrypsin.
Main Results:
- PMNL effectively inactivated Clostridium difficile cytotoxin and Clostridium perfringens phospholipase C, but not C. perfringens enterotoxin.
- Antitoxin activity was associated with PMNL, not mononuclear cells, and correlated with cell concentration.
- The highest PMNL concentrations completely inactivated C. difficile cytotoxin within 2 minutes.
- Fractionation localized antitoxin activity to myeloperoxidase within PMNL's primary granules.
- Protease inhibitors blocked toxin inactivation, suggesting a role for neutral proteases.
- PMNL demonstrated greater activity against C. difficile cytotoxin than purified chymotrypsin.
Conclusions:
- Human PMNL possess significant antitoxin activity against specific bacterial exotoxins, notably C. difficile cytotoxin.
- The antitoxin activity is mediated by neutral proteases located in the primary granules of PMNL.
- PMNL represent a critical component of the innate immune system's defense against certain bacterial toxins.