Changes in peripheral blood lymphocyte subsets in patients undergoing radiotherapy

Area of Science:

• Immunology
• Radiation Oncology

Background:

• Peripheral blood lymphocyte subpopulations play crucial roles in immune response.
• Radiotherapy, a cornerstone of cancer treatment, can affect immune cells.
• Understanding lymphocyte behavior during radiotherapy is vital for managing treatment side effects and efficacy.

Purpose of the Study:

• To investigate the dynamic changes in peripheral blood lymphocyte subpopulations during pelvic radiotherapy.
• To determine the relative radiosensitivity of different lymphocyte subsets (T-helper, T-suppressor/cytotoxic, B-cells, and NK cells) in vivo.

Main Methods:

• Flow cytometry was used to quantify lymphocyte subpopulations in 8 patients undergoing pelvic radiotherapy.
• Measurements were taken throughout the treatment course to track changes.
• Equivalent total body doses were considered to correlate lymphocyte levels with radiation exposure.

Main Results:

• B-cells exhibited the steepest decline, reaching 10% of baseline levels, indicating high radiosensitivity.
• T-lymphocytes (T-helper and T-suppressor/cytotoxic) showed a less pronounced decrease, stabilizing at 20% of initial levels.
• Natural killer (NK) cells demonstrated the least decline, becoming the most radioresistant population by the end of therapy.

Conclusions:

• In vivo, B-cells are the most radiosensitive lymphocytes, while NK cells are the most radioresistant.
• T-helper and T-suppressor/cytotoxic cells showed similar radiosensitivity.
• Findings align with in vitro studies on lymphocyte apoptosis induction following gamma irradiation.