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Immunomodulation of polymorphonuclear leukocytes by D53 Immucytal and its constitutive fractions
F Minonzio1, A M Ongari, E Venegoni
1Istituto di Clinica Medica I, University of Milan.
Abstract:
D53 (Immucytal) is a compositive vaccine made of immunogenic ribosomes extracted from 4 bacterial species (Klebsiella pneumoniae, Haemophilus influenzae, Streptococcus pyogenes and Streptococcus pneumoniae) associated with a membrane proteoglycan from a non-encapsulated strain of Klebsiella pneumoniae (MPG-Kp). In this work we have studied the effect of the compound on human polymorphonuclear leukocyte (PMN) function "in vitro". We have demonstrated that D53 was able to significantly increase Fc- receptor dependent phagocytosis without modify the C3-receptor dependent activity. Furthermore D53 enhanced the oxidative metabolism (evaluated by chemiluminescence) both using cells in resting conditions or after stimulation with phagocytable or soluble stimuli. On the contrary D53 caused a dose-dependent inhibition of PMN migration toward different chemoattractants. Using the two constitutive fractions of the compound (ribosomes and proteoglycans) we have observed that the MPG-Kp component was mainly responsible for the modulating activity of the drug on human PMNs.
Insights
The D53 vaccine enhances immune cell phagocytosis and oxidative metabolism but inhibits migration. The membrane proteoglycan (MPG-Kp) component is primarily responsible for these effects on human polymorphonuclear leukocytes (PMNs).
Area of Science:
- Immunology
- Vaccine Development
- Cellular Biology
Background:
- D53 (Immucytal) is a composite vaccine containing bacterial ribosomes and a Klebsiella pneumoniae proteoglycan (MPG-Kp).
- Understanding the immunomodulatory effects of D53 on human immune cells is crucial for its therapeutic application.
Purpose of the Study:
- To investigate the in vitro effects of D53 on human polymorphonuclear leukocyte (PMN) functions.
- To identify the specific component of D53 responsible for its observed effects on PMNs.
Main Methods:
- In vitro assessment of D53's impact on PMN phagocytosis (Fc-receptor and C3-receptor dependent).
- Evaluation of PMN oxidative metabolism via chemiluminescence.
- Analysis of PMN migration in response to chemoattractants.
- Fractionation of D53 to test individual components (ribosomes and MPG-Kp).
Main Results:
- D53 significantly enhanced Fc-receptor dependent phagocytosis but not C3-receptor dependent activity.
- D53 boosted PMN oxidative metabolism under resting and stimulated conditions.
- D53 exhibited dose-dependent inhibition of PMN migration.
- The MPG-Kp component was identified as the primary driver of D53's modulatory effects on human PMNs.
Conclusions:
- D53 modulates human PMN function, enhancing key microbicidal activities while suppressing migration.
- The membrane proteoglycan (MPG-Kp) from Klebsiella pneumoniae is the main active component responsible for D53's immunomodulatory effects.
- These findings provide insights into D53's mechanism of action and its potential as an immunomodulatory agent.