THE OCCURRENCE OF NATURAL ANTIBODIES TO MINIMAL COMPONENT OF BACTERIAL-CELL WALL (N-ACETYLGLUCOSAMINYL-N-ACETYLMURAMYL DIPEPTIDE) IN SERA FROM HEALTHY HUMANS

ELISA assay showed that sera from each of 729 healthy donors contained antibodies to the minimal component of bacterial cell walls, N-acetyl glucosaminyl-N-acetylmuramyl dipeptide (GMDP). Anti-GMDP antibody leve ls were determined for 686 sera which were classified into 3 groups: h igh (17.6%), medium (68.7%), and low responder (13.7%). Inhibition ana lysis performed on representative sera showed that a proportion contai ned specific anti-GMDP antibodies reacting only with GMDP (i.e., GMDP interaction with anti-GMDP antibodies was inhibited by GMDP only) wher eas the remaining sera reacted both with GMDP and with the tetrasaccha ride (GlcNAc-MurNAc)(2) (i.e., GMDP interaction with anti-GMDP antibod ies in the latter sera was inhibited by both GMDP and the tetrasacchar ide), Inhibition analysis indicated, moreover, that the anti-GMDP anti bodies contained in high-responder sera had higher affinity than those present in low-responder ones: GMDP inhibited the GMDP + anti-GMDP an tibody interaction by 88.7% in the former sera vs. 53% in the latter, Sera contained both IgM and IgG antibodies to GMDP, but the mean level of anti-GMDP IgG antibodies in the high-responder sera was 30 times h igher than in the low-responder ones.