Figure 2. UMCD6 antibody enhances cancer cell killing by PBMCs.

Tumor cells were cocultured and imaged using an IncuCyte system that recorded tumor cell number (B, D, and F, red fluorescence with y axis log₂) and cell death (A, C, and E, green fluorescence, caspase sensitive with y axis linear). (A and B) CD318-expressing MDA-MB-231 cancer cells were plated in a 96-well plate with a seeding density of 20,000 cells with 50,000 PBMCs. Enhanced killing of MDA-MB-231 HBCCs by PBMC was observed in the presence of anti-CD6 (UMCD6) or anti-CD318 (3a11) for caspase expression compared with control antibodies (UMCD6 vs. anti-vWF P = 0.000623; UMCD6 vs. 3a11 P = 0.00401; 3a11 vs. anti-vWF P = 0.0476) and tumor cell survival (UMCD6 vs. anti-vWF P = 0.00223; UMCD6 vs 3a11 P = 0.4507; 3a11 vs anti-vWF P = 0.0078). (C and D) MDA-MB-231 cells were plated at a seeding density of 20,000 cells per well. 50,000 PBMCs were added at 22 hours. Before addition to the cocultures, PBMCs were incubated for 1 hour at 37°C with UMCD6 or mouse IgG control antibodies. (E and F) LNCaP prostate cancer cells were plated at a seeding density of 20,000 cells per well. 50,000 PBMCs were added to the LNCaP cell cultures at 4 hours. Before addition to the cocultures, PBMCs were incubated with UMCD6 or IgG control antibodies. MDA HBCCs and LNCaP cells displayed profound enhancement of clumping and caspase expression in cocultures in which PBMCs were exposed to UMCD6 (A and C). MDA and LNCaP cells also displayed inhibited growth in the wells containing UMCD6-treated PBMCs (B and D). Statistical significance (*P < 0.05) was initially achieved for MDA-MB-231 between the UMCD6- and anti–LFA-1 IgG–treated cocultures at 39 hours (green, caspase cell death) and 51 hours (red, survival). Similarly, differences in LNCaP cell death became significant at 8.5 hours (E) and at 43.5 hours for survival (F) between UMCD6 and anti-vWF IgG cocultures. See Supplemental Videos 1–3 for MDA-231 breast cancer cell killing.