1. General Considerations:
Diseases are caused by biochemical changes in cellular systems or organs i.e. their analysis should permit the establishment of individual patient diagnosis and prognosis.
Especially the knowledge of individual patient prognosis is of high clinical importance. Patient prognosis is, however, not easily obtained from biochemical or other analyses. One of the reasons is that biochemical analysis is mostly performed on non cellular samples like blood plasma, serum or centrifuged urine or liquor cerebrospinalis i.e. the potential cellular prognosis factors may not become apparent.
Humoral biochemistry reflects only indirectly biochemical disease processes in affected organs because cell derived biomolecules may become altered or undetectable in humoral compartments or they may not at all appear outside cells.
Organ tissue biochemistry results are traditionally difficult to interpret because of the simultaneous presence of variable proportions of different organ cell types which may all react differently in disease.
The true advantage of cytometry consists in the combination of microscopic single cell observation with simultaneous multiparameter biochemical analysis.
Cytometry permits the precise quantitation of cellular biomolecules with biochemically specific fluorescent dyes. The simultaneous multiparameter data collection in flow as well as in image cytometry provides high amounts of functional and structural information on heterogeneous and largely unprocessed cell suspensions from fresh ex-vivo samples of the human body close to the in-vivo situation.
Sample heterogeneity, in contrast to most other instances of biochemical analysis is a very welcome feature in clinical and experimental cytometry because of the high information content.
3. Individual Patient Diagnosis and Prognosis by Multiparameter Data Analysis
The evaluation of cytometric multiparameter measurements with self learned classifiers (Ann.NY Acad.Sci 677,235-251(1993)) demonstrated that standardized diagnostic and prognostic patient classifications are obtained in clinically relevant areas such as infection/sepsis/shock prevention, myocardial infarction risk assessment or leukemia/cancer cell immunephenotyping.