Our aim was to determine if T cell-specific stimulation upregulates GM-CSF in T cells and in other immune cell types in the mixed PBMC; to investigate whether this upregulation is higher in MS; to identify factors (perhaps in addition to the known role of IL-2) that may be involved in this upregulation; and to determine whether immunoregulatory factors like TGF-β are produced in lower amounts in MS under these conditions. Here, CSF2 is linked to myeloid sarcoma.