BCGF alpha/beta activity help please

[horst ibelgaufts]

Dear netters,
can anyone of the hard core immunologists out there please explain to me
what is meant when a cytokine has BCGF alpha or beta activity? I know that
BCGF stands for B cell growth factor. What is alpha or beta?

Thanks a lot.

Horst Ibelgaufts
Institute of Biochemistry, c/o MPI of Biochemistry
Munich Martinsried, FRG

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