Evidence indicates that individuals suffering from acquired immune deficiency syndrome (AIDS) are susceptible to severe systemic infections with mycobacteria in the Mycobacterium avium complex (MAC). Very little is known regarding the pathogenesis of the MAC but it has been proposed that these organisms are able to survive postphagocytic destruction because of an inert protective capsule, more recently referred to as the L1 layer. The long-term objective of this project is to study the pathogenic aspects of nontuberculous mycobacteria in the MAC using as a focal point a group of glycopeptidolipid (GPL) antigens which are the major constituent of the L1 layer and are the basis for serotyping mycbacteria in the MAC. Our previous studies have involved the GPL antigens of serovar 20, a MAC serovar not isolated from AIDS patients. The main objective of this proposal is to expand those studies by using the GPL antigens from serovars 4 and 8, the most common MAC serovars isolated from AIDS patients. This project is designed to examine with more specificity the postphagocytic handling of the GPL antigens by host macrophages to determine how they are processed by those cells and to what extent the antigens are degraded. GPL antigens will be labeled with radioisotopes by means of internal labeling techniques designed to radiolabel both the serovar-common fatty acyl peptide core and the serovar-specific oligosaccharide determinant. Radiolabeling will be accomplished with both (3H)- and (14C)-labeled components using techniques previously developed in this laboratory. Purified radiolabeled GPL antigens will be used to pulse both normal and """"""""activated"""""""" peritoneal macrophages which will subsequently be examined for potential GPL-catabolites. Postphagocytic distribution of the GPL antigens will be visually examined by means of immunocytochemical techniques using light and electron microscopy. Because there is a potential for GPL accumulation in host macrophages during an infection, the effect of GPL antigens on various macrophage functions will also be studied. These studies will make it possible to confirm whether these superfical antigens are inert to macrophage degradation and whether or not these antigens compromise the functional activity of host macrophages.
Specific aims are: 1) To confirm cell localization and distribution of GPL antigens from serovars 4 and 8, 2) To internally radiolabel the GPL antigens from serovars 4 and 8, 3) To examine the uptake and retention of GPL antigens by peritioneal macrophages, and 4) To examine the effect of GPL antigens on macrophage function.
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