CD antigens 2001

Engagement of ILT2/CD85j in Sézary syndrome cells inhibits their CD3/TCR signaling

Extensive phenotype analysis of cutaneous T-cell lymphoma (CTCL) malignant cell lines revealed surface expression of receptors usually not detected on normal circulating CD4(+)CD45RO(+) lymphocytes. We previously found that CTCL malignant cells express the killer cell immunoglobulinlike receptor (KIR) KIR3DL2/CD158k, whereas they fail to express the other KIRs. In the present study, we report for the first time that the CD85j/immunoglobulin (Ig)-like transcript 2 (ILT2) receptor is found on Sézary cell lines and on circulating Sézary malignant CD4(+) cells, while it is hardly detectable on circulating CD4(+) lymphocytes from healthy individuals. We demonstrate that ILT2 is functional on CTCL cells, as its triggering leads to the recruitment of Src homology 2 domain-containing tyrosine phosphatase (SHP-1) and to the specific inhibition of CTCL malignant cell proliferation induced by CD3/T-cell receptor (TCR) stimulation. Interestingly, we found that separated CD4(+)ILT2(+) circulating malignant Sézary cells are less susceptible to anti-CD3 monoclonal antibody (mAb)-induced cell death than autologous CD4(+)ILT2(-) lymphocytes. Therefore, the resistance to apoptosis of Sézary cells may result from distinct mechanisms including cytokine-induced high levels of bcl-2 and specific expression of inhibitory receptors involved in lymphocyte survival.

Gangliosides with O-acetylated sialic acids in tumors of neuroectodermal origin

Gangliosides, carrying an O-acetylated sialic acid in their carbohydrate moiety, are often found in growing and developing tissues, especially of neuro-ectodermal origin. The most prominent one is 9-O-Ac-GD3, which is considered as an oncofetal marker in animal and human tumors like neuronal tumors, melanoma, basalioma or breast cancer, as well as in psoriatic lesions. Also other gangliosides like GD2 or GT3 were found to be O-acetylated in their terminal sialic acid. In this review we are summarising the occurrence of such gangliosides in normal and transformed tissues and delineate a more general theory that O-acetylated sialic acids in gangliosides are a universal marker for growing cells and tissues.