R Alam1, S Stafford, P Forsythe
1Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-0762.
You might also read
Articles linked to this work by shared authors, journal, and citation graph.
This study investigated whether RANTES, a cytokine known to attract monocytes and T cells, could also affect eosinophils. Researchers found that RANTES can attract eosinophils at specific concentrations and activate them by increasing the expression of adhesion molecules like CD11b/CD18. They also observed that RANTES caused eosinophils to become less dense, but it did not affect their survival. Additionally, RANTES led to increased release of eosinophil cationic protein, a marker of activation. These findings suggest that RANTES may play a role in recruiting and activating eosinophils during immune responses.
Area of Science:
Background:
Prior research has shown that RANTES belongs to the 8-kDa cytokine family and acts as a chemotactic agent for monocytes and CD4 T cells. However, the role of RANTES in eosinophil behavior remained unclear. Established knowledge includes the function of RANTES in immune cell recruitment, but no prior work had resolved its impact on eosinophil migration and activation. This gap motivated the current investigation into whether RANTES could influence eosinophil chemotaxis and function. Researchers sought to determine if RANTES could act as a chemotactic and activating factor for these cells. The lack of data on RANTES-induced changes in eosinophil adhesion and density prompted this study. Previous findings on other cytokines like IL-3 suggested a potential role for RANTES in eosinophil regulation. This uncertainty drove the need to explore RANTES's effects on eosinophils in detail.
Purpose Of The Study:
The aim of this study was to assess whether RANTES could influence eosinophil chemotaxis and activation. Researchers focused on determining if RANTES could act as a chemotactic agent for eosinophils and whether it could modulate their function. The specific problem addressed was the lack of evidence on RANTES's impact on eosinophils, which are key players in allergic and inflammatory responses. The motivation for this study stemmed from the known role of RANTES in recruiting other immune cells but its unclear effect on eosinophils. The authors sought to evaluate RANTES's ability to induce chemotaxis and activation in purified eosinophils. They also aimed to investigate how RANTES might influence eosinophil adhesion molecule expression. Another goal was to determine if RANTES could alter eosinophil density or survival. The study aimed to provide a clearer understanding of RANTES's role in eosinophil biology.
RANTES acts as a chemotactic and activating factor for eosinophils, promoting their migration and up-regulating adhesion molecules like CD11b/CD18.
Eosinophils were isolated using Percoll gradients to achieve a purity of over 98% before experiments were conducted.
CD11b/CD18 is an adhesion molecule; its up-regulation by RANTES suggests a role in eosinophil activation and migration.
Eosinophils incubated with RANTES became hypodense (<1.085), suggesting a change in cell density linked to RANTES exposure.
RANTES did not influence eosinophil survival in a four-day culture system, unlike IL-3 which does affect survival.
Main Methods:
The study used peripheral blood eosinophils isolated from donors via Percoll gradients to achieve high purity. Chemotaxis assays were performed to assess RANTES's effect on eosinophil migration. Flow cytometry was employed to analyze adhesion molecule expression on eosinophils. Researchers measured eosinophil cationic protein release using a radioimmunoassay. Eosinophil density was evaluated by incubating cells with RANTES and then examining their distribution on Percoll gradients. The study also included a survival assay to determine if RANTES affected eosinophil viability over four days. RANTES concentrations were tested across a range from 10(-9) to 10(-8) M. The experimental design allowed for a comprehensive assessment of RANTES's effects on multiple aspects of eosinophil function.
Main Results:
RANTES was found to be chemotactic for eosinophils at concentrations between 10(-9) and 10(-8) M. The chemotactic response to RANTES was approximately 65% of that observed with 10(-7) M platelet-activating factor. Flow cytometry revealed that RANTES up-regulated CD11b/CD18 expression on eosinophils in a dose-dependent manner. Incubation with RANTES led to increased release of eosinophil cationic protein, as measured by radioimmunoassay. Eosinophils exposed to RANTES became hypodense, with a density below 1.085 on Percoll gradients. This hypodensity effect was distinct from the effects of IL-3, which did not alter eosinophil density. RANTES did not impact eosinophil survival in a four-day culture system. These findings indicate that RANTES can both attract and activate eosinophils.
Conclusions:
The authors concluded that RANTES is a chemotactic and activating factor for eosinophils. Their findings showed that RANTES can induce chemotaxis at specific concentrations. The study also demonstrated that RANTES up-regulates CD11b/CD18 expression on eosinophils. Eosinophil cationic protein release increased in response to RANTES treatment. The hypodensity effect observed in RANTES-treated eosinophils was distinct from that of IL-3. Unlike IL-3, RANTES did not influence eosinophil survival over four days. These results suggest that RANTES may play a role in modulating eosinophil function during immune responses. The authors propose that RANTES contributes to eosinophil recruitment and activation in inflammatory settings.
RANTES treatment increased eosinophil cationic protein release, indicating a functional activation of eosinophils.