Abrogation of tumor induced Ly49 expression on mouse spleen cells by Mitomycin C

Mouse spleen cells were activated with IL2 for 4 days in the presence or ab sence of paraformaldehyde fixed YAC (PFY) tumor cells (spleen cell: PFY rat io 100:1). Fresh spleen cells had poor expression of Ly49A but the expressi on was significantly upregulated by IL2, activation. Addition of PFYs resul ted in a further boosting of Ly49A expression. Besides Ly49A, the Ly49C rec eptors were also upregulated by PFYs. Upregulated Ly49 expression was not r estricted to NK cells (NK1.1 positive cells) but was also seen on T cells ( TCR beta positive cells). Time kinetics studies indicated that maximum upre gulation of Ly49 in response to PFY cells occurred on day 3 and 4 and the e xpression declined thereafter. Ly49 expression in response to PFYs was comp letely blocked if spleen cells were pre-treated with Mitomycin C, an inhibi tor of DNA synthesis. These results show that the addition of a small numbe r of paraformaldehyde fixed YAC cells to spleen cell cultures undergoing IL 2 activation, resulted in a significant upregulation of Ly49 receptors and this process was dependent upon cell proliferative activity. (C) 2001 Elsev ier Science B.V. All rights reserved.