Immune function of sepsis patients in intensive care and intermediate care units
| ISRCTN | ISRCTN18031817 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN18031817 |
| Sponsor | Karolinska Institutet |
| Funders | Vetenskapsrådet, NordForsk, Center for Innovative Medicine, Region Stockholm |
- Submission date
- 07/01/2026
- Registration date
- 15/01/2026
- Last edited
- 12/01/2026
- Recruitment status
- Recruiting
- Overall study status
- Ongoing
- Condition category
- Infections and Infestations
Plain English summary of protocol
Background and study aims
Sepsis is a serious condition where the body’s response to an infection becomes harmful and can lead to organ failure. People with sepsis can look very different from each other, and routine blood tests do not fully capture these differences. The immune system can be overactive in some patients and suppressed in others, and these patterns may change over time. This study aims to map how the immune system responds during sepsis by analysing blood samples collected at several time points. By combining immune measurements with clinical information, the study aims to identify patterns (“profiles”) that are linked to illness severity and could support better patient stratification in the future.
Who can participate?
Adults (18 years or older) who are admitted to an intensive care unit (ICU) or an intermediate care unit and are treated for a suspected infection, with signs of organ dysfunction requiring organ support, may be invited to take part. A comparison group of infected ICU/intermediate care patients who do not meet Sepsis-3 criteria, and a group of healthy volunteers, may also participate.
What does the study involve?
Participants will have blood samples collected as early as possible after ICU/intermediate care admission (within 24 hours). For patients with suspected sepsis, additional blood samples will be collected later during the hospital stay (around day 3–4 and day 8–15) if the participant is still in hospital. Clinical information (such as vital signs, laboratory results, organ support, and outcomes during admission) will be collected from medical records. The blood samples will be analysed using advanced laboratory methods to measure immune cells, gene activity (RNA), and proteins in the blood.
What are the possible benefits and risks of participating?
There may be no direct medical benefit to participants, because the study tests are for research and are not intended to guide immediate clinical care. The main potential benefit is that the findings may improve understanding of sepsis and support better diagnostics and patient stratification in the future. Risks are mainly related to blood sampling, such as temporary discomfort, bruising, bleeding, or rarely infection or dizziness. No experimental treatment is given as part of this study.
Where is the study run from?
The study is run from Karolinska University Hospital (Solna and Huddinge sites), Danderyds Hospital, and Södersjukhuset, in Stockholm, Sweden.
When is the study starting and how long is it expected to run for?
Inclusion of patients started in January 2023 and is expected to continue until December 2027.
Who is funding the study?
The study is funded by the Swedish Research Council, NordForsk, Centre for Innovative Medicine, and Region Stockholm (ALF Medicine).
Who is the main contact?
Kristoffer Strålin, Associate Professor, kristoffer.stralin@ki.se
Contact information
Principal investigator, Public, Scientific
Department of Medicine, Huddinge, Karolinska Institutet, Department of Infectious Diseases, I73, Karolinska University Hospital
Stockholm
14186
Sweden
 ORCID ID |
0000-0002-8801-3169 |
|---|---|
| Phone | +46 70 5927532 |
| kristoffer.stralin@ki.se |
Study information
| Primary study design | Observational |
|---|---|
| Observational study design | Longitudinal study |
| Participant information sheet | 48789_PIS_v1.7_29March2023.pdf |
| Scientific title | Immune profiling of sepsis patients in intensive care and intermediate care units |
| Study objectives | The study is conducted to improve understanding of how the host immune response evolves in sepsis and how immune alterations relate to disease severity and clinical outcomes in critically ill patients. Using systems biology approaches (transcriptomics, high-dimensional proteomics, and high-dimensional flow cytometry) on longitudinal blood samples, the study aims to characterise immune profiles in adult patients admitted to intensive care or intermediate care with suspected infection and organ dysfunction requiring organ support, and to compare these profiles with (i) infected ICU/intermediate care patients who do not fulfil Sepsis-3 criteria and (ii) healthy controls. By integrating detailed clinical data with immune, transcriptomic and proteomic profiles, the study seeks to identify sepsis-associated patient phenotypes with distinct marker-expression patterns and to explore candidate plasma biomarkers that may support risk stratification and precision diagnostics. Sex will be examined as a biological variable in uni- and multivariable analyses. |
| Ethics approval(s) |
Approved 22/03/2021, Ethics Review Authority, Umeå Department of Medicine (Etikprövningsmyndigheten, Umeå avdelning medicin) (Etikprövningsmyndigheten, Box 2110, Uppsala, 750 02, Sweden; +46 10 4750800; registrator@etikprovning.se), ref: 2020-06545 |
| Health condition(s) or problem(s) studied | Suspected sepsis with organ dysfunction in adult patients admitted to intensive care or intermediate care units. |
| Intervention | This is a prospective observational cohort study conducted at Karolinska University Hospital (Solna and Huddinge), Danderyds Hospital, and Södersjukhuset, Stockholm, Sweden. Adult patients are enrolled on admission to an intensive care unit (ICU) or intermediate care unit and meet criteria for suspected sepsis, defined as suspected/probable infection treated with antimicrobial therapy in combination with at least one acute organ dysfunction requiring organ support (aligned with SOFA-related organ dysfunction). The first blood sample is collected within 24 hours of ICU/intermediate care admission. Longitudinal sampling is performed with follow-up samples around day 3–4 and day 8–15 if the participant remains hospitalised. Participants are classified into sepsis and non-sepsis groups based on whether Sepsis-3 criteria are fulfilled prior to the second sampling time point. Samples include EDTA plasma, PAXgene tubes for RNA, and whole blood for cellular analyses; healthy controls are sampled using corresponding procedures. Whole blood is stabilised/cryopreserved and analysed using multiparameter, high-dimensional flow cytometry with specific immune cell panels. Transcriptomic and proteomic analyses are performed on longitudinal samples. Data are quality-controlled and analysed using standardised workflows, including extraction of cell subset frequencies and marker expression, exploratory dimensionality reduction and clustering, and statistical analyses integrating clinical variables. |
| Intervention type | Other |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 31/12/2032 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 18 Years |
| Upper age limit | 100 Years |
| Sex | All |
| Target sample size at registration | 300 |
| Key inclusion criteria | 1. Age: ≥18 years. 2. Setting: Admitted to an intensive care unit (ICU) or intermediate care unit (IMCU/intermediate care). 3. Condition: Suspected sepsis, defined as suspected/probable infection treated with antimicrobial therapy and at least one acute organ dysfunction requiring organ support. 4. Sampling feasibility: Ability to provide study blood samples according to protocol. 5. Consent: Informed consent to participate in the study. |
| Key exclusion criteria | 1. Previously included in the same study. 2. Moribund patient. 3. Informed consent for participation not obtained. |
| Date of first enrolment | 01/01/2023 |
| Date of final enrolment | 31/12/2027 |
Locations
Countries of recruitment
- Sweden
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Data sharing statement to be made available at a later date |
| IPD sharing plan |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Participant information sheet | version 1.7 | 29/03/2023 | 12/01/2026 | No | Yes |
Additional files
- 48789_PIS_v1.7_29March2023.pdf
- Participant information sheet
Editorial Notes
12/01/2026: Study’s existence confirmed by the Ethics Review Authority, Umeå Department of Medicine (Etikprövningsmyndigheten, Umeå avdelning medicin), Sweden.
