From the Guidelines
A reactive enriched T-cell lymphocytic infiltrate is an accumulation of T lymphocytes in tissue that occurs as a response to a stimulus, characterized by an increased number of T cells with features of normal immune activation, rather than malignant transformation. This condition is typically observed in tissue biopsies examined under a microscope by pathologists, and it is commonly seen in response to infections, inflammatory conditions, drug reactions, or autoimmune disorders where the body's immune system is actively responding to a perceived threat 1. The presence of specific subsets of immune cells, such as cytotoxic CD8+ T cells, has been associated with patient survival and response to therapy in various solid tumors, including breast cancer 1.
Key Characteristics
- Accumulation of T lymphocytes in tissue
- Increased number of T cells compared to normal tissue
- Features of normal immune activation rather than malignant transformation
- Commonly occurs in response to infections, inflammatory conditions, drug reactions, or autoimmune disorders
Clinical Implications
The identification of a reactive enriched T-cell lymphocytic infiltrate is important, as it distinguishes this benign accumulation from lymphomas or other malignant processes 1. Treatment is directed at the underlying cause rather than the infiltrate itself, as these cells represent a normal immune response rather than a primary disease process. The degree of lymphocytic infiltration has been shown to have predictive and prognostic value in certain types of breast cancer, such as triple-negative and human epidermal growth factor receptor 2 (HER2+) breast cancer 1.
Diagnostic Considerations
Pathologists identify these infiltrates through specific staining techniques that highlight T cell markers and assess cell morphology and distribution patterns. The evaluation of tumor-infiltrating lymphocytes (TILs) is an important aspect of cancer research, as it can provide insights into the immune response to cancer and the potential effectiveness of immunotherapy 1.
From the Research
Definition of Reactive Enriched T-cell Lymphocytic Infiltrate
- A reactive enriched T-cell lymphocytic infiltrate refers to an increased presence of T cells, particularly CD4+ and CD8+ T cells, in a tissue or organ, often in response to inflammation, infection, or cancer 2, 3.
- This type of infiltrate is characterized by a predominance of T cells, which can be either polyclonal or oligoclonal, and may include regulatory T cells, such as CD4+CD25+ T cells 2, 4.
Composition of Reactive Enriched T-cell Lymphocytic Infiltrate
- The composition of the reactive enriched T-cell lymphocytic infiltrate can vary depending on the underlying condition, but it often includes:
- CD4+ T cells, which are increased in certain conditions, such as Hodgkin lymphoma 2.
- CD8+ T cells, which are also increased in certain conditions, such as Jessner's lymphocytic infiltration of the skin 3.
- Regulatory T cells, such as CD4+CD25+ T cells, which play a role in maintaining immune homeostasis and preventing autoimmunity 4.
- NKT cells, which are increased in certain conditions, such as Hodgkin lymphoma 2.
Clinical Significance of Reactive Enriched T-cell Lymphocytic Infiltrate
- The presence of a reactive enriched T-cell lymphocytic infiltrate can have significant clinical implications, including:
- Prognostic value: The diversity and clonality of the T cell receptor repertoire of tumor-infiltrating T cells can be predictive and prognostic for cancer survival 5.
- Diagnostic value: The composition of the reactive enriched T-cell lymphocytic infiltrate can help distinguish between different conditions, such as Hodgkin lymphoma and reactive lymphoid hyperplasia 2.
- Therapeutic implications: The presence of a reactive enriched T-cell lymphocytic infiltrate can inform the development of therapeutic strategies, such as immunotherapy, which target the immune system to treat cancer or autoimmune diseases 6, 5.