G.P. Sandilands

Correlation between high-molecular-weight Fcγ-receptor-blocking factors in serum and renal allograft survival

In this study, we have demonstrated the occurrence of IgG class noncytotoxic, lymphocyte Fc gamma-receptor-blocking antibodies in a proportion of sera obtained from transfused uremic patients. The presence of these antibodies was not found to correlate with subsequent renal allograft survival. Serum fractionation studies did however reveal a striking correlation between graft survival and Fc gamma-receptor blocking mediated by a serum factor(s) with a sedimentation coefficient of greater than 19S. The precise nature of this factor remains to be clarified.

IMMUNE-COMPLEX INHIBITION OF LYMPHOCYTE Fcγ-RECEPTORS IN PRIMARY BILIARY CIRRHOSIS: A POSSIBLE IMMUNOMODULATORY MECHANISM

20 patients with primary biliary cirrhosis (PBC) had circulating IgG-containing immune complexes. These complexes bind to lymphocyte Fc gamma-receptors in vitro; there was also evidence for in-vivo binding. Such in-vivo binding to T and K lymphocytes may exert an immunomodulatory effect on these cells, and may also explain some of the serological and cellular abnormalities in PBC.

INHIBITION OF Fc-ROSETTE FORMATION BY SERUM OF PATIENTS WITH RENAL ALLOGRAFT REJECTION

Abstract A test which measures the inhibition of Fc-rosette formation by the patients serum was used in a group of 23 renal allograft re- cipients. All 13 serum samples obtained during acute rejection and 2 of 3 obtained during chronic rejection showed strong inhibitory activity, suggesting that the test is of value in confirming the presence of rejection. Its value as a predictive test remains to be established. Preliminary experiments suggest that both immune com- plexes and alloantibodies copntribute to the observed in- hibition of Fc-rosette formation.

Demonstration of Fc Receptors on the Surface of B Lymphocytes

Human blood lymphocytes were tested by an immunofluorescence technique for surface immunoglobulin and by a rosette test with IgG-sensitised red cells for Fc receptors. From combined tests and experiments involving fractionation of lymphocyte populations it is concluded that Fc receptors are demonstrable on most B lymphocytes by the rosette test, but only if the red cells are optimally sensitised. These observations are advanced as an explanation of the discrepant results of surface marker tests on B cells.

Serum-Mediated Inhibition of Human Lymphocyte Fcγ-Receptors in Extrinsic and Intrinsic Bronchial Asthma

Sera from 48 patients with extrinsic asthma and 37 with intrinsic asthma were screened for immune complexes using the EA-rosette inhibition assay. Significant levels of EA-rosette inhibition were found in both groups when compared with normal sera. The serum inhibitory factor(s) is, however, more likely to be an anti-lymphocyte antibody of the IgM class than an immune complex as originally expected.