Antibody against ganglioside GD1c containing NeuGcalpha2-8NeuGc cooperates with CD3 and CD4 in rat T cell activation.
Gangliosides have long been implicated in T cell activation. GD1c with two N-glycolylneuraminic acids [GD1c(NeuGc,NeuGc)] is the predominant ganglioside in rat T cells. In the present study, the anti-GD1c(NeuGc,NeuGc) mAb, AC1, which binds to the NeuGcalpha2-8NeuGcalpha2- sequence, was found to enhance Con A-activated cellular proliferation at a concentration at which AC1 alone did not activate the cells. The potentiation by AC1 was observed more consistently and effectively in the cellular activation elicited by cross-linking of anti-CD3 and anti-CD4, rather than in the cell growth induced by immobilized anti-CD3 alone. Moreover, the combination of immobilized anti-CD4 and soluble AC1 had a remarkable mitogenic effect. In addition, we have demonstrated the existence of a 100 kDa protein in rat T cell lysates which reacts with AC1 on Western blots, and this interaction is abolished by sialidase-treatment of the membrane. Pronase treatment of the T cells, which rendered the 100 kDa protein undetectable on Western-blotting, reduced the number of AC1-positive cells by 40-50% on flow cytometry. On the other hand, all cells became AC1-negative after sialidase treatment. These findings indicated that AC1 reacts with both GD1c(NeuGc,NeuGc) and the 100 kDa glycoprotein on rat T cells. Taken together, these results predict the presence of a novel regulatory mechanism of T cell activation involving CD4 and the NeuGcalpha2-8NeuGcalpha2- sequence.
Nohara
K
K
Environmental Health Sciences Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-0053, Japan. keikon@nies.go.jp
Kunimoto
M
M
Fujimaki
H
H
D000818:Animals; D000906:Antibodies / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D015153:Blotting, Western; D017252:CD3 Complex / Q000276:immunology*; D015704:CD4 Antigens / Q000276:immunology*; D002455:Cell Division; D005732:Gangliosides / Q000737:chemistry / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D009439:Neuraminidase / Q000737:chemistry; D011402:Pronase / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013601:T-Lymphocytes / Q000276:immunology*
D000906:Antibodies; D017252:CD3 Complex; D015704:CD4 Antigens; D005732:Gangliosides; C072151:ganglioside, GD1c; D009439:Neuraminidase; D011402:Pronase