Therapeutic agents targeted to voltage gated calcium channels and compositions comprising such therapeutic agents are provided, as is the use of such agents and compositions to modulate the function of haematopoietic cells expressing the voltage gated calcium channel. Also provided are methods of screening for agents that target a given voltage gated calcium channel that are suitable for use as therapeutics to modulate the activity of cells expressing the targeted voltage gated calcium channel. The agent can be, for example, an antibody, an aptamer, a peptide or a small molecule capable of binding to an ectodomain of the target voltage gated calcium channel and thus of modulating the function of the calcium channel.
