CD45höher

CD45höher refers to cell populations that express high levels of the surface protein CD45, a marker commonly assessed by flow cytometry. The term is used to distinguish cells with bright CD45 expression from those with lower or dim expression, which can indicate different cell types or states within a mixed sample. In many analyses, CD45high gates are used to identify leukocytes and separate them from debris or non-hematopoietic cells.

CD45, also known as PTPRC, is a receptor-type protein tyrosine phosphatase expressed on all nucleated hematopoietic cells. It plays a key role in regulating signaling through receptors for cytokines and antigens, thereby influencing immune cell activation, development, and homeostasis. CD45 has multiple isoforms generated by alternative splicing (such as CD45RA, CD45RB, CD45RC, and CD45RO), which reflect differentiation and activation states in various immune cell subsets. The label CD45high pertains to overall expression density rather than a specific isoform.

In flow cytometry, CD45 brightness is often used in combination with forward and side scatter to gate leukocytes. The CD45high region typically includes many mature leukocytes, while CD45low or CD45dim populations can represent immature cells, certain non-hematopoietic cells in tissue samples, or malignant cells in particular contexts. The exact gating threshold for CD45high is instrument-dependent and relies on proper compensation and controls.

Applications of CD45high gating include immunophenotyping of blood and bone marrow, discrimination of hematopoietic cells from non-hematopoietic material in tissue specimens, and aiding in the classification of leukemias and lymphomas when used together with other lineage markers. It also supports minimal residual disease analyses by helping to define the leukocyte compartment.

Limitations include variability in CD45 expression due to sample handling, activation status, or disease state. Some malignant cells may be CD45dim or display atypical CD45 expression, reducing the reliability of CD45high as a standalone marker. Therefore, interpretation typically requires additional markers and clinical context.