[Cellular targets of immunoglobulins eluted from the placenta]

Placenta eluted gammaglobulin were reported to have a beneficial effect among rheumatoid arthritis suffering patients. These gammaglobulin obtained by acidic elution from washed placentas (PEGG) were compared to plasmatic immunoglobulin (Ig) for their ability to inhibit mixed lymphocyte reaction (MLR), for their content of antibodies (Ab) directed against human tissues or bacteria and viruses. In addition, biochemical fractionations of PEGG were performed. Both PEGG and Ig from plasma (Sandoglobulin [SG]) contained anti nuclear Ab, Ab against smooth muscle, epithelium, vascular endothelium, synovial cells from rheumatoid arthritis synovium. Furthermore, PEGG at high concentration stained the Raji cell line that SG did not stain. PEGG inhibited undirectional MLR by acting on the stimulating cells. SG or plasmin digested Ig from retroplacental blood (Veinoglobulins, Merieux [VG]) also inhibited MLR but at 20 to 50 fold higher concentrations than PEGG. This activity was restricted to intact IgG, even further purified on protein A. Biochemical fractionation indicated that about 10% of PEGG consisted of free light chains, suggesting that deposits of free light chains might exist on placentas.