Figure 3.

Transwell migration assay of CD4+ T lymphocytes in culture medium alone and in the presence of IL-15 (50 ng/mL) in 18 h culture. (A) CD4+ T lymphocytes in the lower compartment of a transwell system in culture medium alone and in culture medium plus IL-15. Photographs were taken with an inverted microscope at 100X after examining 10 different areas of each lower compartment in different experiments with similar results. (B) Representative experiment. Histograms represent the number of non-migrating cells (NMCs) and the number of migrating cells (MCs) in the presence or absence of IL-15. The NMCs are those that, after 18 h of incubation, have remained in the upper compartment of the transwell system, and the MCs are those that, after that time, have crossed the membrane and passed to the lower compartment of the transwell system. (C) Ratio between MCs and NMCs in the two conditions and at 18 h of culture. CD4+ T lymphocytes isolated from peripheral blood samples were deposited in the upper compartment, and in the lower compartments, culture medium alone or culture medium plus IL-15 was added. After the incubation time, the cells were labelled with anti-CD45RA (FITC), anti-CD28 (PE), and anti-CD4 (PerCP). The fraction of CD4+CD28+ and CD4+CD28^null memory T lymphocytes was determined with Kaluza software; * shows significant differences between CD4+CD28+ and CD4+CD28^nulll memory T lymphocytes (p = 0.044); ** shows significant differences between CD4+CD28^null T lymphocytes cultured in medium and in the presence of IL-15 (p = 0.003).