Production of Antibodies Specific for Fc Fab′ and Streptokinase-Streptodornase In Vitro by Peripheral Blood Cells from Patients with Rheumatoid Arthritis and Normal Donors

摘要

To study antibody (Ab) biosynthesis in rheumatoid arthritis (RA), the immunoglobulin (Ig)M anti-Fc, anti-Fab′, and antistreptokinase-streptodornase (SKSD) produced by peripheral blood lymphocytes (PBL) were measured at intervals from 1 to 19 d in culture. PBL from 17 seropositive patients with active RA and 30 age-matched controls were evaluated. Within the first 24 h, PBL from six of eight patients released >30 ng IgM anti-Fc, even in the absence of pokeweed mitogen (PWM). This early release of Ab was blocked by cycloheximide. With or without PWM, PBL from normal donors did not release IgM anti-Fc until after 3-5 d in vitro. By day 9, unstimulated PBL from seven patients made > 100 ng IgM anti-Fc. Un-stimulated PBL from normals never made >95 ng of this Ab.When PWM was added, PBL from normal donors released as much IgM anti-Fc as was found in RA donor cultures. Paradoxically, addition of PWM to PBL of RA patients suppressed release of IgM anti-Fc in 4 of 17 cases to levels significantly below those found in unstimulated cultures of the same cells.Without PWM, PBL from RA donors frequently failed to make IgM anti-SKSD (P < 0.05 compared with normal donors' cells). With PWM, the quantities of IgM anti-SKSD released were comparable.Fluctuations in IgM anti-Fab′ levels during the life-time of these cultures were sufficient to suggest that these Ab may be taken up in immune complexes. This hypothesis was verified by acidifying (pH 3.1) culture supernatants to which ¹²⁵I-Fab′ had been added previously. The samples were then neutralized (pH 7.6) and 12% polyethylene glycol was added to separate free from antibody-bound ¹²⁵I-Fab′. This procedure increased the quantity of ¹²⁵I-Fab′ precipitated by > 10-fold in some cases.These studies suggest that there are a variety of abnormalities in Ab biosynthesis in RA. These include spontaneous synthesis of comparatively large quantities of IgM anti-Fc, relatively suppressed release of IgM anti-SKSD, and a paradoxical reduction, in some cases, in the biosynthesis of IgM anti-Fc after addition of PWM.