Electron microscopical investigations on lymphocyte cytotoxicity against beta-cells in recent onset IDDM.

The effect of lymphocytes from patients with newly diagnosed insulin dependent diabetes on isolated rat or human islets during a 20 h in vitro incubation was investigated by morphological and biochemical methods. All stages of target cell reaction of lymphocytes against beta-cells were observed. Cytoplasmic projections towards and contacts with beta-cells, circumscribed lysis of the outer cell membrane at the contact side and complete lysis of beta-cells were seen. Such findings could not be registered with alpha- or other non beta-cells and in control experiments using lymphocytes from healthy persons. In some cases the lymphocytes were phenotyped using monoclonal antibodies by the indirect immuno-gold technique. It could be demonstrated that lymphocytes in contact with necrotic beta-cells were of the CD8+ve subset. In addition the morphological investigations were supplemented by quantitative biochemical studies measuring the non-secretory insulin release ("cytotoxic" release) from islets into the culture medium and their ability to respond to a consecutive stimulation by arginin with insulin and glucagon secretion. The mean cytotoxic insulin release was 11.3 +/- 1.5 ng/islet/20 h (n = 25) in the diabetic group versus 0.56 +/- 0.15 ng/islet/20 h (n = 15) in the control subjects (alpha less than 0.001). Functional testing of the islets following incubation with lymphocytes from diabetic patients showed diminished insulin (58.6 +/- 5.1%, n = 18, alpha less than 0.001) and unchanged glucagon response (103.0 +/- 3.4%, n = 10, n.s.) when compared with untreated islets (= 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytotoxic anti-T cell antibodies in children with juvenile rheumatoid arthritis.

The object of this investigation was to determine the prevalence of anti-T cell antibodies in 66 children with various connective tissue diseases. Anti-T cell antibodies were found in 43/44 juvenile rheumatoid arthritis (JRA) patients (mean cytotoxicity 15.0%) and in 10/10 children with systemic lupus erythematosus (mean cytotoxicity 20.0%), but in only 1/15 normal controls and in none of 12 children with other arthritides. There was no significant difference in mean percent cytotoxicity among the JRA subclasses. In the JRA patients, the percent cytotoxicity was positively correlated with the erythrocyte sedimentation rate (P = 0.01), but not with the presence or absence of rheumatoid factor, antinuclear antibodies, or immune complexes. The sera of 3 JRA patients repeatedly inhibited the stimulation of normal lymphocytes by mitogens and antigens by 47-99% (measured by the incorporation of 3H-thymidine into DNA) when added to the culture system in the first 24 hours; normal sera did not. Sera from patients with JRA have increased reactivity with mitogen-activated lymphocytes and T cells compared with unstimulated cells as determined by flow cytometry. The expression of the "JRA antigen" requires protein synthesis but not DNA synthesis or cell division. We conclude that the majority of patients with active JRA have cytotoxic anti-T cell antibodies and that in selected patients, these antibodies may play a role in regulation of the immune response.