New chamber for flow cytometric analysis over an extended range of stream velocity and application to cell adhesion measurements.
When analyzed in a flow cytometer, particles are suddenly accelerated to high velocities (1-10 m.s-1) over very short distances. This feature is essential to obtain high analysis rates and low coincidence levels, but translates into very strong velocity gradients (greater than 10(5) s-1): particles experience strong hydrodynamic stresses that elongate them and tend to dissociate weakly associated complexes. In order to analyze fragile conjugates formed by heterotypic adhesion between two cell types, a flow cytometer was modified to make hydrodynamic stress not only much weaker but also adjustable. A new and easily adaptable flow cell was designed for the instruments of the FACS series; it provided satisfactory hydrodynamic conditions on a wide continuous range of flow rates. Accompanying electronic adaptations permitted standard analysis between 0.01 and 10 m.s-1. At 0.01 m.s-1, the velocity gradient roughly amounts to 50 s-1. Conjugates formed by the adhesion between human B and resting T lymphocytes, disrupted in conventional flow cytometers, could be detected and precisely quantified provided analysis velocity was kept below 0.1 m.s-1. We conclude that low velocity flow cytometry makes possible the quantification of weak intercellular adhesion phenomena, and is potentially useful for the future development of new biomechanical techniques and other applications.
Amblard
F
F
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France, Nogent sur Marne, France.
Cantin
C
C
Durand
J
J
Fischer
A
A
Sékaly
R
R
Auffray
C
C
D001402:B-Lymphocytes; D002448:Cell Adhesion; D004581:Electronics; D005434:Flow Cytometry / Q000295:instrumentation*; D006801:Humans; D013601:T-Lymphocytes