A study on IgE antibody-producing cells from the peripheral blood lymphocytes of atopic patients

In the present study, the peripheral blood lymphocytes (PBL) of six rye-grass and 22 ragweed atopic patients demonstrated secretion of IgE antibody from 7-day cultures as measured by a sensitive ultra-low RAST. The RAST binding ranged from 1.5% to 21% whereas the cell supernatants from the PBL of eight non-atopic individuals showed little or no response (1.2%). The addition of antigens (rye grass 1 or AgE) or interleukin (IL-2) to the cultures on day 0 failed to cause an increase in response. But examination of PBL from four of these patients by a reverse hemolytic plaque assay showed that challenge of these cells by antigen or IL-2 caused an increase in the number of antigen-specific IgE plaque forming cells. The bulk of the IgE antibody secreting cells were located in a sheep red blood cell rosetted fraction (cell fraction 2) whereas most of IgE antibody PFC were found in the non-rosetting fraction (cell fraction 1). It appears that the reverse hemolytic plaque assay detects IgE antibody-producing cells which can still undergo immune regulation and may represent an earlier stage of B cell differentiation whereas the ultra-low RAST appears to measure spontaneous plasmablast cell IgE antibody response.