"one standard lithium heparin tube"That is an interesting point...

"one standard lithium heparin tube"

That is an interesting point Alexanders, in the US the approval states that T-Spot can use the following tubes

BD Sodium Citrate Vacutainer CPT
BD Vacutainer Lithium Heparin PST
Greiner Bio-One Lithium Heparin Vacuette

Those that they are not to use are;
BD vacutainer CPT
BD vacutainer CAT
BD vacutainer EDTA

They also recommend Leucosep tubes (Greiner Bio-One) as a time saving approach to Ficoll gradients.

So I dont see any clear distinction being made between producers, only on product specifications.