[Detection of GAD65 reactive T cells in some Chinese subjects initially diagnosed as with idiopathic type 1 diabetes].
OBJECTIVE
To demonstrate the existence of islet-associated antigen-specific T cells in some of type 1B patients.


METHODS
Peripheral blood samples were obtained from 23 classical type 1 diabetes (Type 1A) patients, 29 type 1B patients, and 16 healthy control subjects. Islet-associated autoantibodies were determined by radioligand assay. Human peripheral blood mononuclear cells were isolated by Ficoll-Hypaque density gradients and enzyme linked immune spot (ELISPOT) assay was performed to measure the number of spots-forming plaque. One spot-forming represents a GAD65-reactive IFN-gamma-secreting T (IFN-gamma-T) cell.


RESULTS
The IFN-gamma-spot numbers stimulated with GAD65 were 12 (10.3-20.9) (median and 95% CI) in Type 1A group, 3.5 (3.0-5.7) in Type 1B group, and 1.0 (0.3-1.8) in Control group respectively. The frequency of spots significantly increased in Type 1B group compared to Control group (P<0.05) and there were significantly more spot numbers in Type 1A group than in Type 1B or Control group (both P<0.01). A positive response was determined when the spot number>95% CI of Control subjects. 48.3% (14 of 29) in Type 1B group, 78.3% (18 of 23) in Type 1A and no subject (0) in Control group had positive response, while the numbers of IFN-gamma-spot reactive to phytohemagglutinin (PHA) did not differ among the three groups.


CONCLUSIONS
GAD65-reactive IFN-gamma-T cells are found in similar to Type 1A patients, that abnormal T cell-mediated immunity involved in the underlying aetiology and pathogenesis is also present in some Chinese patients initially diagnosed as with Type 1B diabetes. More rigorous screening for these conditions is needed before classifying subjects as having Type 1B diabetes and ELISPOT assay detecting IFN-gamma-T cells reactivity against GAD65 may contribute to the diagnosis of "autoimmune diabetes mellitus".
Diabetes Center, Institute of Metabolism and Endocrinology, Central South University, Changsha 410011, China.
Yi
Y
Zhang
Zhi-guang
ZG
Zhou
Lin
L
Yang
Hai-feng
HF
Zhou
Jian
J
Lin
Yi
Y
Sun
Gan
G
Huang
D000328:Adult; D001323:Autoantibodies / Q000097:blood; D002681:China; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000276:immunology* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007515:Islets of Langerhans / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
D001323:Autoantibodies; D007371:Interferon-gamma; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2