DETECTION OF MURAMIC ACID IN A CARBOHYDRATE FRACTION OF HUMAN SPLEEN

In previous studies, we showed that peptidoglycan polysaccharides from anaerobic bacteria normally present in the human gut induced severe c hronic joint inflammation in rats. Our hypothesis is that peptidoglyca n from the gut flora is involved in perpetuation of idiopathic inflamm ation. However, in the literature, the presence of peptidoglycan or su bunits like muramyl peptides in blood or tissues is still a matter of debate. We were able to stain red pulp macrophages in all six availabl e human spleens by immunohistochemical techniques using a monoclonal a ntibody against gut flora-derived antigens. Therefore, these human spl eens were extracted, and after removal of most of the protein, the car bohydrate fraction was investigated for the presence of muramic acid, an amino sugar characteristic for peptidoglycan. Using three different methods for detection of muramic acid, we found a mean of 3.3 mu mol of muramic acid with high-pressure liquid chromatography, 1,9 mu mol w ith a colorimetric method for detection of lactate, and 0.8 mu mol wit h an enzymatic method for detection of D-lactate per spleen (D-lactate is a specific group of the muramic acid molecule). It is concluded th at peptidoglycan is present in human spleen not as small muramyl pepti des as were previously searched for by other investigators but as larg er macromolecules probably stored in spleen macrophages.