The cell has complex systems to carry out internal surveillance. It notifies adjacent cells of what is happening inside itself by flagging up evidence of these events on its surface. In doing so, a cell sanitizes its contents - trashing both its own and any invader's genes plus other intracellular structures. Apoptotic debris melts tidily away. Problems arise when zygote derived cells fail to complete a 'controlled shutdown' and so end up spilling their cytoplasms and making a mess.
Gap junctions are transmembrane channels that link the cytoplasms of adjacent cells.
These structures are a cornerstone in the function and subsequent evolution of metazoans. All metazoans have either gap junctions or their plant counterparts - plasmodesmata. This stark uniformity has attracted scant emphasis. There have been few studies of gap junctional intercellular communication in phagocytes and lymphocytes. It has been a broad assumption that lymphocytes are needed to fight infection because, in mammals, the failure of adaptive immunity leads to life threatening infections.