Host Defense MechanismsNCT00339287
Molecular Basis of Human Phagocyte Interactions With Bacterial Pathogens
An observational study of Host Defense Mechanisms, run by National Institute of Allergy and Infectious Diseases (NIAID) at 1 site in United States.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 18 to 120 yearsHealthy volunteers can take part
- Conditions the study is for
- Host Defense Mechanisms
- How many people
- 200 participants
- Where
- 1 siteUnited States
- Study dates
- 12 Feb 2001to not given
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 120 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Volunteers will be selected from a healthy adult population, 21-65 years of age, 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.
Who may be able to join
- 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.
Show all 9Show fewer
- 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.
Who cannot join
None listed.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
NIAID, Rocky Mountain Laboratories
Hamilton, Montana, 59840
About this study
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:
Read more
- Identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
- Investigate phagocyte response mechanisms to specific pathogenic microorganisms.
- 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....
Read the detailed description
Human phagocytic cells such as polymorphonuclear leukocytes (neutrophils or 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 antimicrobial peptides released into forming bacterial phagosomes kill most ingested bacteria. However, many bacterial pathogens have devised means to evade normal phagocyte responses and cause severe disease in humans.
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, projects will address 3 specific aims:
- Identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
- Investigate phagocyte response mechanisms to specific pathogenic microorganisms.
- 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.
- Conditions
- Host Defense Mechanisms
- Keywords
- Virulence, PHAGOCYTOSIS, Neutrophil, Pathogenesis, Natural History
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Healthy volunteers | Healthy adult volunteers at least 18 years of age. |
What is being measured
The primary outcome is the main question the study is designed to answer.
identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
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.
Measured: Ongoing
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Jun 2006 (estimated)
- Study start12 Feb 2001
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Host Defense MechanismsStudies of the same condition, open and under way.
- More trials run by National Institute of Allergy and Infectious Diseases (NIAID)The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Other
- Time perspective
- Other
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
- Investigators
- Frank R De Leo, Ph.D., Principal investigator, National Institute of Allergy and Infectious Diseases (NIAID)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00339287
- Sponsor's protocol ID
- 999901055
- Other IDs
- 01-I-N055
- Status last verified
- 4 Sep 2026
- First submitted
- 19 Jun 2006
- Last updated
- 5 Nov 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Rungelrath V, DeLeo FR. Staphylococcus aureus, Antibiotic Resistance, and the Interaction with Human Neutrophils. Antioxid Redox Signal. 2021 Feb 20;34(6):452-470. doi: 10.1089/ars.2020.8127. Epub 2020 Jun 23.
PubMed 32460514Kobayashi SD, Malachowa N, DeLeo FR. Neutrophils and Bacterial Immune Evasion. J Innate Immun. 2018;10(5-6):432-441. doi: 10.1159/000487756. Epub 2018 Apr 11.
PubMed 29642066
Study at a glance
From the registry record, last updated by the sponsor on 5 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Molecular Basis of Human Phagocyte Interactions With Bacterial Pathogens
- ClinicalTrials.gov ID
- NCT00339287
- Acronym / sponsor ID
- 999901055
- Conditions
- Host Defense Mechanisms
- Keywords
- Virulence, PHAGOCYTOSIS, Neutrophil, Pathogenesis, Natural History
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- National Institute of Allergy and Infectious Diseases (NIAID)US National Institutes of Health
- Study start
- 12 Feb 2001 (actual)
- First posted
- 21 Jun 2006 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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:
- Identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
- Investigate phagocyte response mechanisms to specific pathogenic microorganisms.
- 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....
Detailed description
Human phagocytic cells such as polymorphonuclear leukocytes (neutrophils or 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 antimicrobial peptides released into forming bacterial phagosomes kill most ingested bacteria. However, many bacterial pathogens have devised means to evade normal phagocyte responses and cause severe disease in humans.
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, projects will address 3 specific aims:
- Identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease.
- Investigate phagocyte response mechanisms to specific pathogenic microorganisms.
- 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.
Study design
- Observational model
- Other
- Time perspective
- Other
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Healthy volunteers | – | –Healthy adult volunteers at least 18 years of age. |
Who may qualify
- Ages
- 18 to 120 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Volunteers will be selected from a healthy adult population, 21-65 years of age, 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.
Key inclusion criteria (9 listed)
- 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.
- 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.
Key exclusion criteria (0 listed)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Nov 2026.
- Background: PubMed 32460514Rungelrath V, DeLeo FR. Staphylococcus aureus, Antibiotic Resistance, and the Interaction with Human Neutrophils. Antioxid Redox Signal. 2021 Feb 20;34(6):452-470. doi: 10.1089/ars.2020.8127. Epub 2020 Jun 23.
- Background: PubMed 29642066Kobayashi SD, Malachowa N, DeLeo FR. Neutrophils and Bacterial Immune Evasion. J Innate Immun. 2018;10(5-6):432-441. doi: 10.1159/000487756. Epub 2018 Apr 11.
- Individual participant dataSharing planned: No
Related trials for Host Defense Mechanisms
Not yet recruitingObservational study
Host Response to Infection by Direct Analysis of Leukocyte Single Cell-type Gene Expression/transcript Abundance, Direct LS-TA. a Prospective Study Will Evaluate the Performance of Direct LS-TA in Triage Febrile Patients Into Major Categories of Infections: Viral, Bacterial or Active Tuberculosis.
Single Cell Sequencing Technology, Gene Expression Profiling
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Frank R De Leo, Ph.D. principal investigator
National Institute of Allergy and Infectious Diseases (NIAID)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Host Defense Mechanisms, run by National Institute of Allergy and Infectious Diseases (NIAID) at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 0 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 5 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Frank R De Leo, Ph.D. ((406) 363-9448, fdeleo@niaid.nih.gov), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
identify and characterize specific mechanisms used by pathogenic microorganisms to evade or subvert normal phagocyte responses and therefore cause disease. (time frame: Ongoing). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT00339287, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Nov 2026.