Fig 1: UMCD6 increases cytotoxicity of tumor-infiltrating lymphocytes (TILs). A TILs from breast cancer MDA-MB-231 xenograft tumors were analyzed by flow cytometry 4 days after treatment with UMCD6 or IgG antibodies. TILs from UMCD6-treated mice had higher levels of NK cells (3.14% ± 0.6), NKT cells (18.65% ± 2.25) and CD8 + T cells (16.18% ± 4.28) compared to TILs from IgG-treated mice: NK cells (2.33% ± 0.37), NKT cells (14.72% ± 2.74) and CD8 + T cells (13.90% ± 2.33). On the contrary, CD4 + T cells from UMCD6-treated mice were found in lower proportions (57.16% ± 5.79) compared to IgG-treated mice (62.15% ± 6.28). B We found a significant increased frequency of NK cells (*p < 0.05), specifically CD56 dim cells (*p < 0.05), in UMCD6-treated mice compared to IgG-treated mice. C CD3 + CD56 + NKT cells from UMCD6-treated mice were found to have enhanced perforin expression compared to control-treated mice (*p < 0.05). D CD8 + T cells were found in all mice and showed expression of perforin in UMCD6-treated mice (n.s. versus control group). E UMCD6 down-regulated the percentage of CD4 + T cells (****p < 0.001) while perforin production was significantly up-regulated. Data represent mean of 4–5 animals ± SD. An unpaired t-test was used to analyze differences between TILs from UMCD6 or IgG treated mice