Related Experiment Video
Updated: Jan 26, 2026
Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia
Published on: June 28, 2018
Lymphopenic community-acquired pneumonia is associated with a dysregulated immune response and increased severity and
Raúl Méndez1, Rosario Menéndez2, Isabel Amara-Elori3
1Servicio de Neumología, Hospital Universitario y Politécnico La Fe / Instituto de Investigación Sanitaria (IIS) La Fe, Avenida Fernando Abril Martorell 106, 46026 Valencia, Spain; PhD program in Medicine and Translational Research, University of Barcelona, Barcelona, Spain.
Insights
Lymphopenic community-acquired pneumonia (L-CAP) is linked to higher mortality. This immunophenotype shows depleted CD4+ cells and increased inflammation, indicating greater severity and poorer outcomes.
Area of Science:
- Immunology
- Infectious Diseases
- Critical Care Medicine
Background:
- Lymphopenic community-acquired pneumonia (L-CAP), defined by <724 lymphocytes/µL, is associated with increased mortality risk.
- Understanding the immunophenotype of L-CAP is crucial for predicting severity and patient outcomes.
Purpose of the Study:
- To characterize the L-CAP immunophenotype by analyzing lymphocyte subsets and inflammatory responses.
- To investigate the relationship between L-CAP characteristics and disease severity at presentation and patient outcomes.
Main Methods:
- Prospective study of 217 immunocompetent patients hospitalized with CAP.
- Analysis of lymphocyte subsets (CD4+, CD8+, CD19+, NK cells) and cytokines on days 1 and 4.
- Assessment of immunoglobulin subclasses on day 1 in a subset of patients.
Main Results:
- 39% of patients presented with L-CAP, showing decreased lymphocyte subsets with partial CD4+ and CD8+ recovery by day 4.
- L-CAP patients had higher initial severity, elevated IL-8, IL-10, G-CSF, and MCP-1 levels.
- Low initial IgG2 levels and CD4+ counts (<129 cells/µL) independently predicted 30-day mortality.
Conclusions:
- L-CAP is characterized by CD4+ depletion, heightened inflammation, and low IgG2, correlating with increased severity and worse prognosis.
- The L-CAP immunophenotype serves as a valuable tool for rapid identification of severe cases.
Objectives:
Lymphopenic (<724 lymphocytes/µL) community-acquired pneumonia (L-CAP) is an immunophenotype with an increased risk of mortality. We aimed to characterize the l-CAP immunophenotype though lymphocyte subsets and the inflammatory response and its relationship with severity at presentation and outcome.
Methods:
Prospective study of 217 immunocompetent patients hospitalized for CAP. Lymphocyte subsets (CD4+, CD8+, CD19+, and natural killer [NK] cells) and inflammatory cytokines were analyzed on days 1 and 4, and immunoglobulin subclasses were analyzed on day 1 in a nested group.
Results:
39% of patients showed l-CAP, with decreased levels of all lymphocyte subsets with a partial recovery of CD4+ and CD8+ cells by day 4. l-CAP patients exhibited higher initial severity and systemic levels of interleukin (IL)-8, IL-10, granulocyte colony-stimulating factor, and monocyte chemoattractant protein-1. Initial IgG2 levels were lower in patients with <724 lymphocytes/µL and positively correlated with ALC, CD4+, and CD19+ cell counts. Low CD4+ counts (<129 cells/µL) also independently predicted 30-day mortality after adjusting for age, gender, and the CURB-65 score.
Conclusions:
l-CAP is characterized by CD4+ depletion, a higher inflammatory response, and low IgG2 levels that correlated with greater severity at presentation and worse prognosis. l-CAP is an immunophenotype useful for rapidly recognizing severity.
Related Concept Videos
01:36Humoral Immune Responses
01:40Cell-mediated Immune Responses
01:23Cells of the Adaptive Immune Response
01:29Immune Response Against Viral Pathogens
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
00:30What are Populations and Communities?
01:28Cells of the Innate Immune Response
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...