Distribution of 2B4 in normal and SAP-deficient CD8⁺ T cells. (A) 2B4 distribution in normal CD8⁺ CTLs (T) either alone or at the contact with EBV⁺/CD48⁺ JY B cells or EBV^-/CD48^-K562 cells. Representative cells are shown as bright field (i-iv) and 2B4 staining (v-viii). The white arrows indicate 2B4 clustering at the cell contact area. (B) 2B4 distribution in SAP-deficient CD8⁺ T cells either alone or at the contact with EBV⁺/CD48⁺ JY B cells. Representative cells are shown as bright field (i-ii) and 2B4 staining (iii-iv). (C) Quantitative analysis of the percentage of CTLs (normal or SAP deficient) with clustered 2B4 at the cell contact area. ▪ indicates normal CTL + JY; ▦, normal CTL + K562; and □, SAP-deficient CTL + JY cells. Mean percentages (± SDs) of 3 experiments counting T cells forming clusters with single target cells (100 conjugates were counted). Statistical analysis was performed using an unpaired t test, and P values corresponding to the comparison of 1 group with the other are indicated.