Allelic exclusion of Ly49-family genes encoding class I MHC-specific receptors on NK cells.
Held, Werner; Roland, Jacques; Raulet, David H.
[Letter] Nature. 376(6538):355-358, July 27, 1995.

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An important feature of natural killer (NK) cell activity is the lysis of cells that have extinguished expression of some or all class I major histocompatibility (MHC) molecules *RF 1-7*. Accordingly, the Ly49A NK-cell antigen receptor has been shown to deliver an inhibitory signal to NK cells on encounter with Dd or Dk class I MHC on target cells [4]. Ly49A belongs to a family of eight or more highly related, tightly linked genes [2,8-10]. Expression of Ly49A and Ly49C, another member of the Ly49 family with distinct MHC specificity, define subpopulations of NK cells that are only partly overlapping [10-12]. The mechanisms regulating the expression of Ly49 family members are unknown. We show here that the Ly49A and Ly49C NK-cell receptors are each subject to allelic exclusion. Because Ly49 genes are not thought to undergo DNA rearrangement [13,14], allelic exclusion of Ly49 genes could involve a mechanism distinct from that used by B and T lymphocytes [15,16] and is likely to play an important role in the genesis of a putative NK-cell repertoire specific for class I molecules.

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