Plasma from insulin-dependent diabetics inhibits theophylline sensitive T-lymphocytes demonstrated in E-rosette assay.

This study concerns the effect of plasma from patients with insulin-dependent (type 1) diabetes mellitus (IDDM) on the capacity of normal donor lymphocytes to form rosettes with sheep erythrocytes. Parallel incubations were made of normal allogeneic peripheral lymphocytes with plasma from patients with IDDM and from normal donors. Lymphocytes incubated with plasma from 16 patients with newly diagnosed IDDM displayed a mean rosette formation percentage of 48 +/- 2, but 54 +/- 1 when incubated with control plasma (p less than 0.01). Repeated study in the same patients in the remission period gave similar findings; 46 +/- 2 and 53 +/- 2 (p less than 0.01) respectively. After fractionation of the donor lymphocytes, the reduced rosette formation percentage, after incubation with plasma from the diabetics, was found to be within the theophylline sensitive fraction of the lymphocytes, while the rosette formation percentage in the theophylline resistant fraction was normal. The reduction in rosette formation capacity at the time of diagnosis seemed to be independent of the tissue type of the patient. No relationships were apparent between rosette formation percentages and C-peptide, blood glucose values or glucosuria, neither at time of diagnosis nor in the remission period. The glycaemic control was found to be of no significance in rosette formation percentages in a triple study of 7 patients; first badly controlled, then very well controlled, and, finally again poorly controlled, though without severe ketoacidosis. The theophylline sensitive fraction of T-lymphocytes has been assumed to include suppressor T-cells. It is not known at present whether the described inhibition of these lymphocytes is of any pathogenetic significance.