DIABETES-INDUCED WITH LOW-DOSES OF STREPTOZOTOCIN IS MEDIATED BY V-BETA-8.2(-CELLS() T)

T-cells have been shown to cause insulitis and ultimately be responsib le for the destruction of beta-cells in animal models of insulin-depen dent diabetes mellitus (IDDM). In one murine model, insulitis and hype rglycemia occur after administration of five low doses of streptozotoc in (STZ) (multidose STZ-induced diabetes mellitus [MDSDM]). Insulitis can first be identified in the islets after the final (fifth) daily do se of STZ is given. We have studied the T-cells that infiltrate the is lets of Langerhans during the early stages of diabetes by preparing So uthern blots of T-cell receptor (TCR) beta-chain genes amplified by po lymerase chain reaction (PCR) from islets from C57BL/KsJ mice given mu ltiple doses of STZ. The relative abundance of TCR gene products in is lets was compared with spleen cells stimulated with anti-CD3 monoclona l antibody (mAb). We found that after the fourth dose of STZ, there wa s a striking increase in the amount of V beta 8.2 TCR gene product (37 +/- 4% of total PCR signal) compared with T-cells in the spleen (9 +/ - 2%, P < 0.01), which increased further 2 days after the final dose o f STZ (47 +/- 5%, P < 0.001). We studied the heterogeneity of the size of the V beta 8.2 TCR CDR3 region and found primarily products with o nly two lengths compared with a heterogeneous population in the spleen . Treatment with anti-V beta 8 mAb, but not anti-V beta 9 and anti-V b eta 13 mAbs, prevented development of hyperglycemia (P < 0.0001) and i nsulitis (P < 0.0005) after STZ administration. We conclude that there is limited heterogeneity of the T-cell response that causes diabetes in MDSDM. A limited number of V beta 8.2(+) cells are preferentially e xpanded in the islets in the early stages. Our results suggest that in this model of IDDM, a limited number of T-cells cause the disease.