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Insulin-dependent diabetes mellitus (IDDM) has both genetic and auto-immune components. In patients with acute onset of IDDM, proteins called superantigens (SAGs) have been identified. These SAGs are capable of activating whole families of T cells, of which some are autoreactive T cells that destroy insulin producing beta cells.
Swiss and Italian investigators examined pancreatic islet tissue from two individuals with acute onset IDDM and found evidence of a retrovirus called IDDM (1,2) 22, which was not found in control patients. Subsequently, 10 recent onset IDDM patients had serum examinations that demonstrated genetic sequences from this retrovirus; no similar findings were found in controls.
The investigators postulate that IDDM (1,2) 22 produces a SAG that evokes specific autoreactive T-cells that destroy pancreatic islet cells. The process may be induced by physiologic events such as the increase in steroid hormones at puberty, or by infections such as herpes viruses. The authors conclude that the gene may be transmitted either as an inherited trait or as an infectious agent.
Science and Medicine News. Lancet 1997;350:341.