Release of surface-expressed lactoferrin from polymorphonuclear neutrophils after contact with CD4+T cells and its modulation on Th1/Th2 cytokine production

It is conceivable that a membrane components) is transferred from antigen-presenting cells to T cells after antigenic stimulation. However, it is not clear whether a certain membrane component(s) is transferred from polymorphonuclear neturophils (PAIN) to T cells for immunomodulation. In the presence study, we cocultured two of the three autologous cells-PAIN, CD4(+)T, and red blood cells (RBC)-homotypically or heterotypically for 1 h. Spontaneous membrane exchange between autologous PAIN-PAIN and PMN-CD4(+)T but not between CD4(+)T-CD4(+)T or RBCCD4(+)T was observed with a confocal microscope. Loss of membrane exchange between two paraformaldehyde-fixed cells suggests that mutual membrane exchange is via cell-cell contact. Different combinations of cellular enzyme-linked immunosorbent assay for measuring the binding between fixed cells and biotinylated cell lysates showed the same tendency. To identify the molecule(s) mediating PAIN-CD4(+)T binding, we compared the banding of biotinylated PAIN lysates and the banding of plain PAIN lysate probed by biotinylated CD4(+)T lysate in 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We found that a 75- to 80-kDa surface-expressed molecule on PAIN exists constantly to mediate PAIN-CD4(+)T binding. Peptide analysis disclosed that the molecule had 99.8% identity with lactoferrin (LF). The expression of LF on system lupus erythematosis (SLE)-PAIN is less than normal PAIN. PAIN-CD4(+)T coculture increased LF expression on CD4(+)T. Normal PAIN and human milk-derived LF suppressed interferon-gamma (IFN-gamma) but enhanced interleukin (IL)-10 production of anti-CD3+antiCD28-activated, normal CD4+T. In contrast, coculture of SLE-PMN and autologous CD4(+)T suppressed IFN-gamma and IL-10 production. These results suggest that the surface-expressed LF released from PAIN after contact with autologous CD4(+)T modulated its T helper cell type 1 (Th1)/ Th2 cytokine production. Decreased LF expression on SLE-PAIN abnormally modulates Th1/Th2 production by CD4(+)T cells. J. Leukoc. Biol. 80: 350-358;2006.