In type 1 (insulin-dependent) diabetes mellitus (IDDM) CD8(+) T cells
represent the majority of lymphocytes which infiltrate the pancreatic
islets during beta cell destruction. Soluble CD8 antigen (sCD8) has be
en shown to correlate with CD8 cell subset activation. In this study w
e measured by ELISA sCD8 levels in sera from: 33 newly diagnosed IDDM
patients; 29 type 1 diabetics with duration of disease more than 1 yea
r; 37 healthy siblings of IDDM patients; 19 healthy controls. Sera fro
m both groups of IDDM patients and from healthy siblings exhibited sol
uble CD8 mean levels significantly higher than controls (P = 0.0001, P
< 0.003, P < 0.03 respectively). Soluble CD8 levels above the normal
range (mean +/- 2 s.d. of controls) were found in a percentage of newl
y diagnosed subjects (54.5%) significantly higher than in subjects wit
h a long-standing duration of disease (6 9%, P < 0.0005) and healthy s
iblings (16.2%, P < 0.002). Our results suggest that the raised levels
of soluble CD8 near to diabetes onset may indicate the activation of
CD8(+) T cells probably responsible for the autoimmune beta cell destr
uction.