Deferred Procedure Calls are managed in NT by a DPC kernel objects (as opposed to Executive objects such as semaphores, events, file objects). There are two ways that DPCs can be used. If a device will only have one interrupt in progress at time, then the I/O Manager's DPC functions can be used. This course would be the one that would be a logical choice if you are using system IRP queuing.
Two functions are used when you rely on the I/O Manager's DPC management. The first, IoInitializeDpcRequest, initializes a dpc object and associates it with a particular device object. If you refer to the NT DDK kernel-mode function reference you'll see that it takes just two parameters: a device object and the address of a deferred procedure call function being registered. The DPC object that is initialized is the one that is contained in a device object.
When your ISR wants to request a DPC it calls the I/O Manager function,IoRequestDpc. this function takes a pointer to a device object, a pointer to an IRP, and a context parameter. At some later point the deferred procedure call that was registered for the device will be called and is passed the DPC object, a pointer to the device object, pointer to the IRP, and the context argument.