Tsütomeetria

Tsütomeetria, or cytometry in Estonian terminology, is the branch of science that measures and analyzes physical and chemical characteristics of individual cells or particles. It combines optical, fluorometric, and sometimes impedance-based methods to quantify properties such as size, granularity, and molecular markers. The field encompasses several techniques, with flow cytometry being the most widely used, and image cytometry as a complementary approach that relies on high-content imaging of cells.

Flow cytometry analyzes cells or particles as they pass in single file through a focused light source, usually a laser. Detectors measure forward scatter (cell size), side scatter (internal complexity), and fluorescence from labeled probes or antibodies. This allows rapid, multiparameter characterization of heterogeneous cell populations. Image cytometry uses automated microscopy and image analysis to extract morphological and marker information from fixed samples, enabling spatial context and high-content phenotyping.

Typical workflow involves preparing a single-cell suspension, labeling with fluorochrome-conjugated antibodies or dyes, and running samples through a cytometer. Data are recorded as events with multiple parameters and analyzed with software that defines cell subsets through gating strategies. Special applications include immunophenotyping in hematology, cancer diagnostics and monitoring (such as minimal residual disease), cell cycle analysis, apoptosis, viability testing, and functional assays.

History-wise, cytometry emerged in the 20th century with impedance-based particle counting and later fluorescence-based flow cytometry; fluorescence-activated cell sorting (FACS) became a key advancement in the 1970s. Today, cytometry is widely used in clinical laboratories and biomedical research to study cellular composition, function, and interactions.