CD4 and type 1 diabetes mellitus: Immunological abnormalities including autoimmunephenomena are believed to contribute to the pathogenesis of IDDM.In IDDM, IL-2 production by CD4-positive T lymphocytes within theIL-2 system is thought to be selectively defective [22].Deficient production of IL-2 has been reported in IDDM, but itscause has not been elucidated [23,24].