Research Article: Minimally expanded breast cancer tumor-infiltrating-lymphocytes provide guidance for therapeutic selection
Abstract:
The analysis of tumor-infiltrating lymphocytes often requires techniques that expand their numbers, potentially introducing bias. To address this, we performed a detailed analysis of minimally cultured TILs to evaluate whether this approach better preserves their characteristics.
The TIL culture method was based solely on tumor tissue with low IL-2 supplementation to minimize artificial alterations. The validity of this approach was confirmed by the correlation between CD3+ T cell percentages in cultures and infiltration patterns observed by immunohistochemistry. Immunophenotyping, cytokine release, and TCR repertoire analysis were used to characterize CD4+ and CD8+ T cell subsets and their molecular features during minimal expansions.
High TIL infiltration areas did not consistently correspond to an increased presence of any T cell subset; both CD4+ and CD8+ T cells frequently coexisted in these regions. In contrast, low TIL infiltration sections often displayed a higher proportion of CD4+ T cells. An inverse correlation between CD4+ T cell percentages and cytotoxic molecules was observed, indicating reduced cytotoxic activity in low-TIL sections with abundant CD4+ T cells. TCR repertoire analysis revealed differences between T cell subsets: CD4+ T cells were associated with longer TRA CDR3 nt and shorter TRB N(D)N nt lengths, along with lower diversity, while CD8+ T cells did not exhibit significant correlation with any TCR feature.
This study highlights the distinct biological features of CD4? and CD8? TIL populations within the tumor microenvironment that can be preserved using a minimally expanded TIL approach. The observed associations between IHC patterns, T cell subset composition, cytotoxic potential, and TCR repertoire diversity help identify which biopsy regions yield TILs with greater therapeutic potential, thus providing guidance for TIL selection in immunotherapy.
Introduction:
The analysis of tumor-infiltrating lymphocytes often requires techniques that expand their numbers, potentially introducing bias. To address this, we performed a detailed analysis of minimally cultured TILs to evaluate whether this approach better preserves their characteristics.
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