Amifostine enhances recovery and expansion of peripheral FAS/CD95+ T- and NK-cell subpopulations during radiotherapy of patients with head-neck cancer

Abstract

Purpose: Experimental studies suggest that the FAS/APO-1/CD95 (cytokine receptor protein TNF-receptor superfamily, member 6) cell surface molecule is involved in the apoptotic effect of radiotherapy. In this study we investigated the role of amifostine in protecting the CD95+ (CD: cluster of differentiation) lymphocytic subpopulation in patients with head and neck cancer undergoing radiotherapy.

Materials and methods: Using flow-cytometry we examined the expression of FAS/CD95 antigen on CD4+ (helper/inducer T cells), CD8+ (suppressor/cytotoxic T cells) and CD56+ (NK, natural killer) T-lymphocytes of 28 patients with head and neck cancer undergoing radiotherapy (with and without amifostine).

Results: The numbers of peripheral blood lymphocytes were significantly reduced after treatment from (mean value ± STD error) 1477 ± 129 to 1015 ± 77 for T lymphocytes, 700 ± 70 to 454 ± 38 for CD4, 449 ± 46 to 296 ± 34 for CD8 and, 140 ± 18 to 118 ± 13 for NK, before and after treatment, respectively. CD95 expressing lymphocytes showed a faster recovery rate in patients receiving amifostine. CD95 expressing CD56 lymphocytes increased during radiotherapy in patients receiving daily cytoprotection with amifostine to values higher than the pre-treatment levels (p = 0.004).

Conclusion: It is suggested that amifostine enhances recovery of T- and NK-lymphocyte subpopulations expressing the CD95 antigen in head-neck cancer patients undergoing RT and may enhance the efficacy of the later by interfering FAS-related immunological pathways.

Keywords:

• T-lymphocytes
• CD95
• FAS
• amifostine
• radiotherapy
• head neck cancer