CD4 and breast cancer: In a small group (n = 15), we found that patients with metastatic HER2 + breast cancer and high serum levels of miR-19a-3p (indicating a good prognosis) had a trend of a higher ratio of CD4 + IFN-γ + /CD4 + IL-4 + T cells in their peripheral blood compared to those with low serum levels of miR-19a-3p (indicating a poor prognosis).