Immunophenotyping using gold or silver nanoparticle‐polystyrene bead conjugates with multiple light scatter

Background The type of antibody‐conjugated polystyrene (PS) latex beads for use as light scatter shift agents for targeted lymphocyte populations in whole blood has been expanded to include gold and silver nanoparticle‐aminodextran‐PS latex bead conjugates with antibodies. The linkers between antibody and colloidal metal were an aminotrithiol ligand or aminodextran polymer molecules. Methods A modified flow instrument, including forward light scatter (FS), side light scatter (SS), light scatter at other intermediate angle ranges, LMALS (10–20°) and UMALS (20–65°) was used for simultaneous bead probe measurements. A conventional flow cytometer was used in simultaneous bead‐fluorescent marker experiments. Results Two mutually exclusive cell populations, CD4+ and CD8+ lymphocytes, have been simultaneously enumerated in blood by using a mixture of CD4‐PS, CD8‐Au‐PS or CD4‐Au‐PS, CD8‐PS beads, and one laser line, 633 nm, excitation. Similar measurements were made with mixtures of CD4‐PS, CD8‐Ag‐PS or CD4‐Ag‐PS, CD8‐PS beads. Also, simultaneous use of bead and fluorescent markers mixed with whole blood was demonstrated with CD4‐PS beads and with the CD4‐RD1/CD8‐FITC dual marker. Conclusions Enumeration of CD4 and CD8 lymphocytes in whole blood by light scatter parameters only compared well with standard analyses with fluorescent markers. In simultaneous bead‐fluorescent marker labeling of lymphocytes, the labeled bead had to be mixed first with cells in whole blood. Cytometry 41:298–307, 2000. © 2000 Wiley‐Liss, Inc.