Identification of factors responsible for failure to up-regulate CD80 on DCs.

Examples of up-regulation or down-regulation of CD80 expression on blood DCs of patients with myeloma (A-C), blood DCs of healthy donors (D), and blood monocytes of healthy donors (E). (A) Addition of either anti–TGF-β or anti–IL-10 (1.25 μg/mL) neutralized the inhibition of the up-regulation of percentage of CD80-expressing DCs of a patient after stimulation with huCD40LT and IL-2. (B) Addition of either anti–TGF-β or anti–IL-10 failed to alter the percentage of CD80-expressing DCs of a patient when there was normal up-regulation of CD80. (C) Neutralization of the failure to up-regulate CD80 expression on DCs of patients was dose dependent, and levels below 1 μg/mL did not completely block the inhibition. rTGF-β₁ caused a dose-response inhibition of the expected up-regulation of CD80 expression on DCs (D) and monocytes (E) from a healthy donor.