Particle-labeled antibodies. I. Anti T-cell antibodies attached to plastic beads by poly-L-lysine.

A simple and inexpensive method for the detection of T-cell surface antigens is introduced using polyacrylic plastic beads (PAA-beads) as indicator particles. The beads are easily visible in ordinary light microscope and make the method convenient for routine laboratory use, also in laboratories possessing no special equipment.The method is an indirect test using a first, absorbed rabbit anti-T serum to sensitize the cells and a second, sandwich antiserum (goat anti-rabbit Ig) coupled to the indicator beads. Instead of glutaraldehyde used by other investigators to attach antibodies to the beads, we used poly-l-lysine which did not affect antibody titers.The F(ab)₂ fragment of the sandwich goat anti-rabbit Ig antibody was employed to avoid binding of antibody-coated beads to Fc-receptor-bearing cells. Sensitivity, specificity and reproducibility of the method were tested on murine and human lymphoid cells treated with the respective anti-T serum. The data obtained show that the sensitivity of the method depends on: (a) the bead concentration, (b) the concentration of F(ab)₂ fragment of the second antiserum used to coat the beads, and (c) the concentration of specific antibody used to sensitize the cells. Specificity and reproducibility of the method were found to be good. The percentage of positive cells with this method are in good agreement with those reported by means of well established immunological methods.