Cellular Immunoprofile of Peritoneal Environment During a HIPEC Procedure

Area of Science:

• Oncology
• Immunology
• Surgical Oncology

Background:

• Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) are critical in treating peritoneal carcinomatosis.
• Understanding the peritoneal immune microenvironment during these procedures is essential for optimizing treatment outcomes.

Purpose of the Study:

• To characterize the dynamic changes in peritoneal immune cell populations during cytoreductive surgery and HIPEC.
• To identify distinct immune profiles within the peritoneal fluid and their potential clinical correlations.

Main Methods:

• Prospective collection of peritoneal fluid during laparotomy and HIPEC at multiple time points (0, 30, 60, 90 minutes).
• Flow cytometric analysis using leukocyte gating and specific antibodies for immune cell subsets (stem cells, B lymphocytes, T-helper, T-suppressor, NK cells).
• Assessment of peritoneal carcinomatosis index (PCI) and completeness of cytoreduction (CCR) scores.

Main Results:

• Peritoneal natural killer (NK) cell proportions remained stable throughout HIPEC (p=0.655).
• The CD4/CD8 and granulocyte/lymphocyte ratios significantly changed during cytoreduction but stabilized during HIPEC (p=0.019, p=0.018).
• Two distinct T-lymphocyte patterns (high vs. low CD4/CD8 ratio) were observed, with high CD4/CD8 ratios correlating with longer cytoreduction duration (p=0.019).

Conclusions:

• The peritoneal immune cellular profile exhibits dynamic changes during cytoreductive surgery, followed by a stable phase during HIPEC.
• Distinct immune phenotypes, characterized by CD4/CD8 ratios, emerge and persist during HIPEC.
• Further research is needed to elucidate the clinical significance of these peritoneal immune phenotypes in patients undergoing HIPEC.