DavidHC, some thoughts:

"It doesn't seem to settle the issue [VDR ablation] either way, almost a technical way of saying we just don't know what's going on, but there's stuff happening. ."

I could not have put it better myself

"B-cells are also affected by 1,25(OH)2D, demonstrating decreased immunoglobulin production, proliferation and differentiation, but increased apoptosis."

I think that this is OK. Most B cells are passive. They only get activated by encountering specific antigens made by pathogens, usually with assistance from helper T cells. Two things happen to activated B cells; they differentiate into passive memory cells which are "ready and waiting" for the next time that their specific pathogenic antigen is present - they then get activated - this is why vaccinations are effective.

Activated B cells also differentiate into plasma cells, which secrete specific antibodies, which deal with the pathogen. If both activated B cells and plasma cells persisted in the absence of their specific antigen there is a risk that they could mutate, leading to an autoimmune disease or a B cell cancer like multiple myeloma. Because of that they "commit suicide" - undergo apoptosis - it seems that Vitamin D/VDR has a role in this.

"Computer simulation is not enough."

Commented on elsewhere.

"this study seems to take it for granted that inhibiting the ongoing proliferation of activated B cells and inducing their apoptosis is beneficial."

See above.

"keeping an eye on my IgG and neutrophils, which I should mention have slightly gone down in the last few months - I have two blood samples over 3 months on that - and the reading was already on the lowest end of the acceptable range."

I don't know enough about the clinical side of things to say much about this - mrsD could well help.