An in-vitro assessment of the functional activity of monoclonal anti-D

Abstract

The response of human monocytes to red cells sensitized with known levels of monoclonal antibody to the Rh antigen D (anti-D) was compared with that of polyclonal anti-D. Monocyte response was determined by measuring red cell adherence, erythrophagocytosis, monocyte-mediated red cell lysis and luminol-dependent chemiluminescence. By all criteria, monoclonal and polyclonal antibodies showed comparable activity, with IgG3 antibodies promoting a greater monocyte-red cell interaction than IgG1 antibodies. It is suggested that monoclonal anti-D may be effective in the prophylaxis of haemolytic disease of the newborn, providing such material is clinically acceptable.

Ability of Monoclonal Anti-D Antibodies to Promote the Binding of Red Cells to Lymphocytes, Granulocytes and Monocytes

“…Rosette assays with human lymphocytes, monocytes and granulocytes were performed with red cells sensitized with varying, known levels of IgG 1 or IgG3 monoclonal anti-D antibodies and were repeated several times for each antibody (as shown in parentheses); 1A3 (8) failure of at least some monoclonal IgGl anti-D antibod ies to promote lymphocyte-mediated red cell lysis [13] while both monoclonal and polyclonal antibodies pro mote monocyte-mediated red cell lysis [14], The reason for the discrepant results with lymphocytes is not certain but it is possible that some factor other than the IgG subclass is of importance in lymphocyte rosetting and that this was not present in any of the monoclonal antibodies tested in this study. In a recent study with monoclonal anti-D s of differing Gm allotypes [24] the allotype Glm [3] was most effective in the lymphocyte ADCC assay and in the ADCC assay the Gm allotype appears to be of greater importance than the IgG subclass.…”

In vitro Functional Activity of lgG1 and lgG3 Polyclonal and Monoclonal anti-D

“…Sera containing solely IgG3 anti-D have been found to be considerably more active in promoting haemolysis of red cells in monocyte-mediated ADCC assays than sera in which only IgGl anti-D was detected, at comparable levels of red cell sensitization [19]. Similar results were obtained for several IgGl and IgG3 monoclonal anti-D [9,19] and were confirmed in this study for both monoclonal and poly clonal anti-D. It was furthermore shown here that maximal levels of monocyte-mediated haemolysis were obtained with polyclonal anti-D consisting of 10% or more IgG3.…”

Results of Tests with Different Cellular Bioassays in Relation to Severity of RhD Haemolytic Disease

“…Some references to the techniques used are as follows: ADCC(M) assay: as used at laboratories 1, 2, and 5, [1]; at laboratory 3, [5]; at laboratory 6, [6]. ADCC(L) assay: as used at laboratories 1 and 3, [2], Chemiluminescence: as used at laboratory 3, [7]; at laboratory 6, [8].…”

“…ADCC(L) assay: as used at laboratories 1 and 3, [2], Chemiluminescence: as used at laboratory 3, [7]; at laboratory 6, [8]. Adherence and phagocytosis with peripheral monocytes: as used at laboratory 3, [5]; at laboratory 5, modified [to be published] from [9]: at laboratory 6, [10]; at laboratories 7 and 8, [9] as modified from [11] and at laboratory 9, [13], modified from [12], Macrophage binding assay using U937 cells, as used by laboratory 3, [14] and using monocytederived cultured macrophages, previously stimulated with immune in terferon: as used at laboratory 4 [15], Table 2 lists the samples: those from mothers of infants with haemolytic disease are grouped according to the sever ity of the disease. The table also shows the tests used and the laboratories at which they were carried out and gives the results of the tests on a scale of 1-3, 3 being the greatest degree of positivity.…”