The role of CD52⁺ cells in the primary immune response to KLH.

(A) The effect of CD52 depletion on the presentation of KLH by irradiated PBMCs to purified autologous CD4 T cells. Proliferation was assessed after 7 days' culture by uptake of ³H. Results shown are the mean of triplicate readings + SEM. CD52 depletion resulted in significant inhibition of the response to KLH. (B) The effect of lineage depletion, CD52 depletion, CD52 and CD123 depletion, and add-back of purified CD3⁺, CD14⁺, and CD19⁺ cells to CD52-depleted cells on the presentation of KLH to autologous purified CD4 cells. Lineage depletion enhanced the presentation of KLH, while add-back of CD3⁺, CD14⁺, and CD19⁺cells failed to reconstitute the activity in CD52-depleted cells. Further depletion of CD123⁺ from the CD52⁻ fraction had no effect. The significance of the results obtained is shown above the columns in question and the values for nonadjacent columns are indicated by double arrows. Each panel represents a separate experiment using a different donor.