T-cells are produced within nurse macrophages.

<p>(A) Immunophenotype of nonadherent cells harvested from cultures of replated EDTA-recovered macrophages after 112 hours of exposure to IL-2. The forward (FSC) versus side (SSC) scatter plot shown on the left indicates the gate used for the other plots. As can be seen, the vast majority of cells are CD4+ T-lymphocytes. The 7-AAD plot indicates that these cells were viable. (B) Confocal microscopy images showing that the CD3+ cells present within this large MHC II+ macrophage appear as an organized array. This culture of replated EDTA-recovered macrophages was photographed on day 10 of exposure to IL-2. Size bar: 50 µm. (C) Confocal microscopy images illustrating CD3+ cells within a CD68+ macrophage at day 10 of IL-2 exposure. Free CD3 antigen deposition is also apparent within the macrophage (white arrow, far left panel), as is budding of a CD3+ cell from the macrophage surface (green arrow, far right panel). Boxed insert in the center panel is an enlargement of the cell identified by the white arrow. Small pockets of CD68 antigen can be seen within this CD3+ cell near the top edge. Size bar: 20 µm. Z indicates the Z-stack level(s) for each image. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040139#pone.0040139.s004" target="_blank">Fig. S4</a> for a gallery view of this series. (D) Time-lapse video images of a lymphocyte budding from a macrophage in a replated culture exposed to IL-2 for 7 days. (The budding cell is a lymphocyte, based on its subsequent nonadherent post-bud behavior. Data not shown.) Numbers below the arrows refer to the time interval in minutes and/or seconds between the two images. Arrowheads identify the position of the budding cell, which first becomes apparent in the second panel.