EXPRESSION OF CR2 (C3d RECEPTOR) ON THE CELL MEMBRANES OF ADULT T CELL LEUKEMIA

MT ‐ 2 cells, which produce human T‐cell lymphotropic virus type I (HTLV‐I), are known to have a complement receptor. We have established that the complement receptor is CR2 which binds C3d on immune complexes but not CR1. CR2 was also detected on ATL‐3I cells but no complement receptor was detected on ATL‐1K cells which lack ATL antigen (ATLA). Since CR2 is not detectable on normal T lymphocytes, the presence of CR2 on some ATL cells might suggest that ATL cells were derived from a particular minor lineage of T cells, or HTLV‐I has a capacity to induce CR2, which has been demonstrated to be an α‐type growth factor for B lymphocytes and to be a receptor for Epstein‐Barr virus.