Paired receptors consist of highly related activating and inhibitory receptors and are widely involved in the regulation of the immune system. PILRB is thought to act as a cellular signaling activating receptor that associates with ITAM-bearing adapter molecules on the cell surface. Seems to associate with DAP12 and is a receptor for CD99. May be involved in target cell recognition by natural killer cells and in activation of dendritic cells. Interacts with CD99. Probably associates with DAP12. Widely expressed with highest levels in spleen, liver and lung. Predominantly expressed by natural killer cells, macrophages, and granulocytes and dendritic cells (BM-DC).