Abstract
Immunomicrospheres consist of hydrophilic cross‐linked particles with antibodies bound to their surface. These particles find specific receptors on living or fixed cells and there fore can label cell sub‐populations and the labelled cells can be observed by means of a scanning, electron or light‐microscope. To label cells with polymeric particles, biocompatible microspheres are needed preferably with a narrow distribution of sizes in the range 10 to 10,000 Å.
Particles having a gel‐like nature and high porosity seem to meet the biocompatibility requirement and they do not stick non‐specifically to cell membranes. Use of cross‐linking agents renders the microspheres insoluble in common solvents. Therefore, subsequent reactions with molecules of biochemical interest are possible in various media.
Five classes of hydrophilic cross‐linked microspheres with functional groups e.g. carboxyl, hydroxyl, amide and/or pyridine groups were synthesised. These functional groups were used to bind covalently antibodies and other proteins to the surface of the microspheres. To optimise the derivatisation technique, polyglutaraldehyde immunomicrospheres have been prepared and utilised. Specific populations of human and murine lymphocytes were labelled with microspheres synthesised either by the emulsion or the ionising radiation technique. The labelling of the cells by means of microspheres containing an iron core led to a successful separation of B from T lymphocytes by means of a magnetic field.