NCT00339287 · National Institute of Allergy and Infectious Diseases (NIAID)
Molecular Basis of Human Phagocyte Interactions With Bacterial Pathogens
What this study is about
Human phagocytic cells such as polymorphonuclear leukocytes (PMNs) are readily mobilized to sites of infection and ingest microorganisms by a process known as phagocytosis. The combined effects of reactive oxygen species (ROS) and proteolytic peptides and enzymes released into forming bacterial phagosomes kill most ingested bacteria.
View original scientific description
Human phagocytic cells such as polymorphonuclear leukocytes (PMNs) are readily mobilized to sites of infection and ingest microorganisms by a process known as phagocytosis. The combined effects of reactive oxygen species (ROS) and proteolytic peptides and enzymes released into forming bacterial phagosomes kill most ingested bacteria. However, many human bacterial pathogens have devised means to subvert normal phagocyte responses and the innate immune response and cause severe disease. The overall objective of this study is to elucidate specific features of pathogen-phagocyte interactions that underlie evasion of the innate immune response or contribute to the pathophysiology of disease or inflammatory disorders. Therefore, specific projects will: 1. Identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease. 2. Investigate phagocyte response mechanisms to specific pathogenic microorganisms. 3. Identify specific bacterial structures and/or (gene) products that dictate differences in phagocyte responses among a range of pathogens so that generalized statements can be made about the pathophysiology of disease states. The studies will be performed using multiple techniques including state-of-the-art equipment for genomics and proteomics strategies to identify target bacterial genes/proteins of interest or those up-regulated in phagocytes. Phagocyte-pathogen interactions will be examined using fluorescence-based real-time assays and video microscopy, confocal and electron microscopy in combination with enzymatic assays for ROS production, routine biochemistry, immunology and cell biology. Implementing these studies will require isolation of phagocytic leukocytes from venous blood of healthy human volunteers. The study population will be all-inclusive except in certain instances where individuals possess genetic defects that impair phagocyte function (e.g., myeloperoxidase-deficiency) or have altered phagocyte function due to outside influences such as recent bacterial or viral infection. The proposed studies will likely provide new information pertinent to understanding host cell-pathogen interactions and the pathophysiology of inflammatory conditions....
Primary outcome measures
identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
Time frame: Ongoing
The study involves the use of human subjects as a source of blood for in vitro assays with bacteria, the isolation of hematopoietic cells (polymorphonuclear leukocytes, mononuclear phagocytes, erythrocytes, and lymphocytes), and serum as a source of complement, antibody, and matrix-binding proteins.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Exclusion criteria
- Volunteers will be selected from a healthy adult population, 18 years of age or older, with no known medical problems and will generally be NIH employees working at Rocky Mountain Laboratories (RML) or within the community of Hamilton, MT. No race or gender is excluded from the donor pool and reflects the diversity of the community and that of the employees at RML. The specific criteria for eligibility are as follows:
- Subjects must fit the definition of "healthy adults" as assessed by the medical/health screening evaluations, and willing to have blood and/or tissue samples stored for future use.
- Inasmuch as all subjects are RML employees, they will be 18 years of age or older.
- Children are excluded.
- Pregnant women will be identified by verbal history and are not eligible to donate blood for this protocol.
- The study population will be all-inclusive except in certain instances where individuals possess genetic defects that impair phagocyte function (e.g., myeloperoxidase-deficiency) or have altered phagocyte function due to outside influences such as recent bacterial or viral infection.
- Individuals below the normal hematocrit and hemoglobin ranges will be excluded from the protocol.
Where
- Hamilton, Montana
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
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Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
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Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
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Data: ClinicalTrials.gov · synced Jul 16, 2026 · Source of record for eligibility and locations