Activation of primary T lymphocytes leads to a polarized morphology and CD43 redistribution but activation of thymocytes does not.

These results are representative of 3 independent experiments. (A) CD4⁺ spleen T cells were conjugated with beads coated with anti-CD3 and anti-CD28, fixed, and stained for CD43. The cells were analyzed by immunofluorescence microscopy as described in “Materials and methods.” They clearly change shape on activation and accumulate CD43 toward the opposite from the contact site end of the cell. The arrows indicate location of the beads. (B) Sorted thymocytes were activated with beads coated with anti-CD3 and anti-CD28, fixed, and stained for CD43. To obtain an enriched double-positive population of the thymocytes, cells were sorted by CD8⁺ selection. The activated thymocytes had a predominantly round shape without CD43 polarization. (C) Quantitation of thymocyte response to activation. The bars represent the cells polarized as a percentage of bead-conjugated cells from 3 experiments. The results for predominantly double-positive thymocytes (striped bar) and for CD4⁺ splenocytes (white bar) are shown. One to 2 slides with 80 to 120 bead-conjugated cells counted on each were evaluated in an experiment. The error bars represent 1 SD. The difference for cell shape polarization was significant at P < .0005 and the difference for CD43 polarization was significant at P < .00005. Original magnification × 1000.