CD4 and diabetes mellitus: Beyond neutrophil changes, people with diabetes have alterations in the function of several cell types including macrophages, Natural Killer cells, CD4 T cells and CD8 T cells function.97 T cell responses are known to be important in host defence against intracellular pathogens, with intracellular antigens presented to CD8 T cells via the MHC Class 1 antigen presentation pathway, and digested antigens from both extracellular and intracellular sources presented to CD4 T cells via the MHC Class 2 system.