Ligation of CD28 by its natural ligand CD86 in the absence of TCR stimulation induces lipid raft polarization in human CD4 T cells

Kovacs B, Parry RV, Ma Z, Fan E, Shivers DK, Freiberg BA, Thomas AK, Rutherford R, Rumbley CA, Riley JL and Finkel TH
Source: J Immunol
Publication Date: (2005)
Issue: 175(12): 7848-7854
Research Area:
Immunotherapy / Hematology
Cells used in publication:
T cell, human peripheral blood unstim.
Species: human
Tissue Origin: blood
Nucleofector® I/II/2b
Stimulation of resting CD4 T cells with anti-CD3/CD28-coated beads leads to rapid polarization of lipid rafts (LRs). It has been postulated that a major role of costimulation is to facilitate LR aggregation. CD86 is up-regulated or expressed aberrantly on immune cells in a wide array of autoimmune and infectious diseases. Using an Ig fusion with the extracellular domain of CD86 (CD86Ig) bound to a magnetic bead or K562 cells expressing CD86, we demonstrated that ligation of CD28 by its natural ligand, but not by Ab, induced polarization of LRs at the cell-bead interface of fresh human CD4 T cells in the absence of TCR ligation. This correlated with activation of Vav-1, increase of the intracellular calcium concentration, and nuclear translocation of NF-kappaB p65, but did not result in T cell proliferation or cytokine production. These studies show, for the first time, that LR polarization can occur in the absence of TCR triggering, driven solely by the CD28/CD86 interaction. This result has implications for mechanisms of T cell activation. Abnormalities in this process may alter T and B cell tolerance and susceptibility to infection.