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Updated: Jul 22, 2026

Murine Model of CD40-activation of B cells
Published on: March 5, 2010
A role for CD99 in T cell activation
D Wingett1, K Forcier, C P Nielson
1Department of Veterans Affairs Medical Center, Boise, Idaho, 83702, USA. denise.wingett.med.va.gov
Abstract:
The function of the T cell surface protein CD99 was investigated in human CD4(+) peripheral T cells. Crosslinking of the CD99 molecule using anti-CD99 mAbs in the presence of anti-CD3 Ab resulted in a marked enhancement of proliferation. CD99 coligation also enhanced CD25 expression and early markers of T cell activation, CD69 and CD40L. Ligation of CD99 resulted in the pronounced tyrosine phosphorylation of an approximately 29-kDa protein suggesting that a specific CD99-induced signal transduction pathway may exist. Simultaneous costimulation with anti-CD99 and anti-CD28 Abs appeared to have additive effects on CD40L expression while CD99 ligation had no effect on CD2-mediated T cell induction of CD40L expression. These results demonstrate that CD99 signal transduction can deliver effective costimulatory signals to T cells.
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