Effect of Smoking and Time of Day on Eosinophils

June 1, 2026 updated by: Marek Lommatzsch

Effects of Acute Smoking and Time of Day on Blood Eosinophils in Humans

The study investigates the effect of acute smoking and time of day on blood eosinophils in chronic smokers. Chronic cigarette smokers without chronic respiratory diseases smoking at least 8 cigarettes per day and never-smoking controls are examined. Blood eosinophil counts and surface molecules are measured at 8 and 12 am in both groups. In smokers, two measurements are performed (at least 4 weeks apart): one measurement with no smoking between 8 and 12 am, and another measurement with smoking of 8 cigarettes between 8 and 12 am.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

20 chronic cigarette smokers without chronic respiratory diseases smoking at least 8 cigarettes per day and 20 never-smoking controls are recruited. Blood eosinophil counts and surface molecules are measured at 8 and 12 am in both groups. In smokers, two measurements are performed (at least 4 weeks apart, cross-over design): one measurement with no smoking between 8 and 12 am, and another measurement with smoking of 8 cigarettes between 8 and 12 am. The effects of the time of day (comparing 8 and 12 am) and the effects of acute smoking (comparing the effects of no smoking or acute smoking at 12 am) on blood eosinophil counts and surface molecules (using flow cytometry) are analyzed. Additional parameters examined: lung function, exhaled nitric oxide, total and specific IgE in serum.

Study Type

Interventional

Enrollment (Estimated)

20

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

  • Name: Johann C. Virchow, Prof.
  • Phone Number: +49-381-494-7461

Study Locations

  • Germany
      • Rostock, Germany, 18057
        • Recruiting
        • University of Rostock
        • Contact:
        • Contact:
          • Johann C Virchow, Prof.
          • Phone Number: +49-381-494-7461

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Healthy current smokers
  • Age between 18-50 years
  • Smoking of at least 8 cigarettes/day

Exclusion Criteria:

  • Chronic respiratory diseases
  • Any treatment with corticosteroids or other immunosuppressants
  • Any acute illness

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: A: Smoking of 8 cigarettes in 4 hours
Smoking
Other: Smoking for 4 hours
Smoking of 8 cigarettes in 4 hours
No Intervention: B: No smoking for 4 hours
No Smoking

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Blood eosinophil counts
Time Frame: 8 am (baseline) and 12 am (follow-up after intervention)
Blood eosinophil counts in cells/µl blood
8 am (baseline) and 12 am (follow-up after intervention)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Blood eosinophil surface molecules
Time Frame: 8 am (baseline) and 12 am (follow-up after intervention)
Blood eosinophil surface molecules (such as CD62L or CD294), measured using flow cytometry
8 am (baseline) and 12 am (follow-up after intervention)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Marek Lommatzsch

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

February 7, 2026

Primary Completion (Estimated)

June 30, 2026

Study Completion (Estimated)

December 6, 2026

Study Registration Dates

First Submitted

May 26, 2026

First Submitted That Met QC Criteria

June 1, 2026

First Posted (Actual)

June 4, 2026

Study Record Updates

Last Update Posted (Actual)

June 4, 2026

Last Update Submitted That Met QC Criteria

June 1, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Smoke-Time-Eosinophils

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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