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Updated: Aug 11, 2026
Evaluation of Tumor-infiltrating Leukocyte Subsets in a Subcutaneous Tumor Model
Published on: April 13, 2015
Expression of CD45 isoforms in fresh and IL-2-cultured tumor-infiltrating lymphocytes from basal cell carcinoma
Q H Nguyen1, R L Moy, M D Roth
1Division of Dermatology, UCLA School of Medicine 90024.
Insights
Tumor-infiltrating lymphocytes in basal cell carcinoma (BCC) primarily show an activated (CD45RO) phenotype. Interleukin-2 (IL-2) expansion further enhances this memory T cell marker expression in both tumor-infiltrating and naive lymphocytes.
Area of Science:
- Immunology
- Dermatology
- Oncology
Background:
- Basal cell carcinoma (BCC) is a common skin cancer.
- Understanding the tumor microenvironment, particularly T cell populations, is crucial for immunotherapy.
- T cell phenotypes, such as naive (CD45RA) and memory (CD45RO), indicate immune cell activation and history.
Purpose of the Study:
- To characterize T cell subpopulations infiltrating BCC.
- To investigate the phenotypic response of tumor-infiltrating lymphocytes (TIL) to interleukin-2 (IL-2) in vitro.
- To determine if IL-2 alone can induce naive T cells to adopt a memory phenotype.
Main Methods:
- Immunohistochemistry and flow cytometry were used to analyze T cell phenotypes.
- Tumor-infiltrating lymphocytes (TIL) from BCC were isolated and cultured with IL-2.
- Purified naive (CD45RA+) lymphocytes were cultured with IL-2 to assess phenotype conversion.
Main Results:
- TIL in BCC predominantly expressed the CD45RO (memory) phenotype (65%).
- IL-2 expansion increased CD45RO expression in TIL (to 85%).
- Naive peripheral blood lymphocytes (79% CD45RA+) shifted to CD45RO+ (86%) after IL-2 expansion, with 90% expressing CD45RO exclusively after 3 weeks.
Conclusions:
- TIL in BCC are predominantly memory T cells (CD45RO+).
- IL-2 promotes the conversion of naive T cells to a CD45RO+ phenotype, independent of antigen or mitogen.
- CD45RO expression on TIL may reflect antigen-specific stimulation or cytokine-driven activation within the tumor microenvironment.
Abstract:
Immunohistochemistry and flow cytometry analyses were performed to characterize the specific T cell subpopulations infiltrating basal cell carcinomas (BCC) and to determine their phenotypic response to in vitro expansion with IL-2. Tumor-infiltrating lymphocytes (TIL) within BCC predominantly expressed the CD45RO (activated or "memory") phenotype (65 +/- 3%) and the percentage of TIL expressing CD45RO consistently increased when cultured in vitro with IL-2 (85 +/- 5%). In comparison, fresh normal peripheral blood lymphocytes predominantly expressed the CD45RA (naive) phenotype (79 +/- 4%), but shifted to the expression of CD45RO following in vitro expansion in IL-2 (86 +/- 6%). To determine whether IL-2 alone, in the absence of antigen or mitogen, can promote naive lymphocytes to convert from the expression of the CD45RA isoform to the CD45RO isoform, we cultured purified CD45RA+ lymphocytes in IL-2. After three weeks in culture, 90% of the lymphocytes expressed exclusively CD45RO. We conclude that tumor-infiltrating lymphocytes from BCC predominantly express CD45RO and that this expression may represent specific antigen stimulation and/or in situ activation by cytokines.
