MODULATION OF LY49A RECEPTORS ON MATURE CELLS TO CHANGES IN MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-I MOLECULES

The expression of murine Ly49 receptors on natural killer (NK) cells a nd NK1.1(+) T cells is believed to prevent these cells from responding against normal self-tissues. In this report we investigated whether t he expression level of Ly49A was fixed on mature cells or if it could be adapted as the major histocompatibility complex (MHC) class I envir onment changed in vivo. By transferring peripheral T cells from Ly49A transgenic mice into BALB/c nude/nude and B6 nude/nude mice, we demons trated that mature cells modulate their Ly49A receptor expression rela tive to the in vivo MHC class I environment. These results indicated t hat the expression of the inhibitory Ly49A receptor is not permanently fixed during a maturation and/or education process but rather is adap ted to MHC class I changes on the surrounding cells.