Are you sure the low neutrophils was from DMSA and not from the mercury itself? Did your neutrophil level get worse after you started DMSA?

"Mercury from amalgam interferes with production of cytokines that activate macrophage and neutrophils, disabling early control of viruses and leading to enhanced infection(131,251). Mercury’s activation of inflammatory cytokines and Th2 helper immune cells suppresses the cytotoxic response of T-cells and natural killer immune cells that are the body’s main defense against viruses and such biological pathogens(181,472,580). Animal studies have confirmed that mercury increases effects of the herpes simplex virus type 2 for example(131). Mercury damages the immune system and in those with chronic conditions has been found to commonly facilitate infestation by pathogens such as viruses, harmful bacteria, candida, mycoplasma, and parasites"

http://www.flcv.com/cfsfm.html