Human CD[8.sup.+] T cells do not require the polarization of lipid rafts for activation and proliferation

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Publisher: National Academy of Sciences
Document Type: Abstract
Length: 223 words

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Abstract :

Lipid rafts are important signaling platforms in T cells. Little is known about their properties in human CD[8.sup.+] T cells. We studied polarization of lipid rafts by digital immunofluorescence microscopy in primary human T cells, using beads coated with anti-CD3 and anti-CD28 mAbs (CD3/28 beads). Unlike CD[4.sup.+] T cells, CD[8.sup.+] T cells did not polarize lipid rafts when stimulated with CD3/28 beads, when the anti-CD28 antibody was substituted with B7.21g, or if an anti-CD8 antibody was added to the CD3/28 beads. This phenomenon was also observed in human antigen-specific CD[8.sup.+] T cells. On stimulation with CD3/28 beads, the T cell antigen receptor clustered at the cell/bead contact area in both CD[4.sup.+] and CD[8.sup.+] T cells. Examination of lipid rafts isolated by sucrose density gradient centrifugation revealed the constitutive expression of [p.sup.56]Lck in the raft fractions of unstimulated CD[8.sup.+] T cells, whereas [p.sup.56]Lck was recruited to the raft fraction of CD[4.sup.+] T cells only after stimulation with CD3/28 beads. Stimulation with CD3/28 beads induced marked calcium flux, recruitment of PKC-[theta] and F-actin to the cell/bead contact site, and similar proliferation patterns in CD[4.sup.+] and CD[8.sup.+] T cells. Thus, polarization of lipid rafts is not essential for early signal transduction events or proliferation of human CD[8.sup.+] lymphocytes. It is possible that the lower stringency of CD[8.sup.+] T cell activation obviates a requirement for raft polarization.

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Gale Document Number: GALE|A95105711