Differential antigen presentation of hepatitis B surface antigen on cell membranes of responder and nonresponder mice.

In several systems it has been shown, that non-responsiveness to an antigen in mice of a particular haplotype is due to the lack of binding of an immunogenic peptide to class II molecules. Such studies have been done using detergent solubilized, affinity purified class II molecules. It has been reported, that the presence of certain phospholipids around class II molecules dramatically alters the extent of peptide binding to these molecules. It thus appears that the milieu in which the class II molecules are inserted influences to a considerable extent the level of peptide binding. Hence it is likely that the kinetics of binding of immunogenic peptides to class II on the cell surface, may be different from that of molecules inserted in detergent micelles. We therefore decided to test this by studying the binding of radiolabeled peptides to class II molecules on cell membranes. We report here a rapid and sensitive assay for peptide binding to murine class II molecules on cell membranes. Further, we have used this assay to study the nature of the interaction of immunogenic peptides and class II molecules on cell membranes of mice who are responders and non-responders to Hepatitis B surface Antigen (HBsAg). Interestingly, we find that immunogenic peptides bind in good correlation with their MHC restriction. We also observed that the HBsAg derived peptide which is unable to elicit a T cell response in the non-responder but fails to make a stable class II-peptide complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Plate beamsplitter to produce multiple equal-intensity beams.

The design of a plate beamsplitter to produce multiple beams of equal intensity is presented. Multiple beams of equal intensity can be obtained from a plate by varying the reflectances of the front and back surfaces. The application for which we designed the plate beamsplitter was a fourbeam multiplexed galvanometric scanner for a confocal scanning microscope. Multiplexing with four beams increases the effective optical scanning rate (and therefore the confocal imaging rate) to four times the electromechanical scanning rate of the galvanometrically driven mirrors.