  Biological and biomimetic membranes often contain aggregates of embedded or
adsorbed macromolecules. In this article, the indirect interactions of
cylindrical objects adhering to a planar membrane are considered theoretically.
The adhesion of the cylinders causes a local perturbation of the equilibrium
membrane shape, which leads to membrane-mediated interactions. For a planar
membrane under lateral tension, the interaction is repulsive for a pair of
cylinders adhering to the same side of the membrane, and attractive for
cylinders adhering at opposite membrane sides. For a membrane in an external
harmonic potential, the interaction of adsorbed cylinders is always attractive
and increases if forces perpendicular to the membrane act on the cylinders.
