Differential expression of a 70 kDa O-glycoprotein on T cells: a possible marker for naive and early activated murine T cells

We purified a 70 kDa O-glycoprotein that binds to the GalNAc specific lectin from Amaranthus leucocarpus (ALLr) and determined its expression pattern on T lymphocytes from different murine lymphoid organs. High level of ALLr expression was demonstrated in 95–98% of both CD4+8+ and CD4−8+ thymocytes, and in 80–95% of CD8+ T cells from peripheral blood, lymph nodes, and spleen, whereas a minor fraction of CD4+8− thymocytes (46–67%) and peripheral CD4+ T cells (9–40%) showed low ALLr expression. Peripheral CD19+ B cells were ALLr negative and most of the peripheral ALL+ T cells showed a CD62LhiCD45RBhiCD44lo/− phenotype, indicating features of naive cells. Mitogenic activation of peripheral T cells increased 3-fold the number of ALL+CD4+ T cells 24 h after stimulation, as opposed to a >80% decrease in CD8+ T cells 72 h after stimulation. Our results suggest that ALL detects a non-described surface O-glycoprotein selectively expressed by naive CD8+ T cells and by early activated CD4+ T cells.