The Soluble Form of CTLA-4 from Serum of Patients with Autoimmune Diseases Regulates T-Cell Responses
Immunoregulatory properties of sCTLA-4. (a) sCTLA-4 containing sera from autoimmune patients (55AIT, 71AIT, 34CD, 101CD, 1PBC, and 24PBC) are able to inhibit significatively a MLR. CTLA-4 Ig fusion protein is a positive control of inhibition of proliferation. Sera from autoimmune patients negative for sCTLA-4 (21AIT, 13CD, and 61PBC) do not affect the proliferation rate. The data represent the mean of quadruplicate samples. The averages standard deviations (error bars) of three different experiments are shown. Positive or negative sera are indicated by an alphanumeric code followed by and , respectively. (b) We show that the inhibitory effect on T lymphocytes proliferation is related to sCTLA-4 and is not due to a different serum protein, by using sCTLA-4-deprived sera (55AIT, 34CD, 101CD, and 24PBC). As depicted from the graphic, depleted sera are unable to alter significatively the proliferation in this assay. Controls are the same sera before the treatment with the capture mAb specific for sCTLA-4 (see Section 2). In addition, sera resulted to be negative for sCTLA-4 (21AIT and 13CD) following the deprivation method did not change their inability to affect proliferation. A representative experiment out of five is shown.