CD4 and lobular neoplasia: The aim of the present study was to investigate the effect of IL-15 on cytotoxic CD4 + CD28− T cell activities in LN patients, describe the population and properties of CD4 + CD28− T cells in LN, and determine whether circulating and local IL-15 produced by macrophages could provide excess IL-15 to CD4 + CD28− T cells, thus producing the tissue-infiltrating and cytotoxic effects leading to potential renal impairment in vivo.