Protective effect of original endotoxin protein and possible immunological mechanism

Pseudomonas aeruginosa has been known as one of the major causative microorganisms of the opportun: istic infection. However, a variety of chemotherapeutic :m easures have been found to be unsatisfactory because of its intrinsic resistance to most of currently used chemotherapeutic agents and of its ability to acquire antimicrobial resistance. Therefore, immunological measures have been tried as an alternative approach to preγent pseudomonas infection. In this study, original endotoxin protein(OEP) , which was purified from autolytic culture lysates of P. aeruginosa N•10 , was studied 、，v i t h respect to its preventive effect in pseudomonas infection and its possible mechanisms of action. The preventive effect was evaluated by comparing LDso of P. aeruginosa in burned mice with or 、iv i t h o u t OEP immunization (5μg/mouse， twice) The protective mechanism of OEP 、 as studied in the aspect of the humoral immune response and phagocytic and bactericidal activities of peripheral polymorphonuclear leukocytes in the immunized mice. The results were as follows. 1. LD50 of P. aeruginosa was significantly (0、er the 95% confidence interval) increased in the OEP immune ICR mice, against challenge with 13 serotYr:es of P. aeruginosa isolated from clinical specimen of Seoul National University Hospital 2. After OEP immunization, rising of agglutinin titer to 10 kinds of P. aeruginosa serotype were olserved. Ten serotypes was as follow; A(Pa-13), DCPa 48) , E(Pa-16) , GCPa•55) , H(Pa-79) , I(Pa•49) , ](Pa-84), K(Pa-80) , LCPa-83) , and M(Pa-85) But agglutinins to 3 kinds of P. aeruginosa, serotype B(Pa-4) , C(Pa•29) and F serotype (Pa9) were not ohserved. 3. Only 5. 696 of P. aerugiηosa were survived after reacting with the OEP immune rabbit serum with complement for 24 hrs , at 4'C. Decreasing viable P. aerugiηosa after reacting with the OEP immune rabbit serum was partially inhibited by absorbing the OEP immune serum with Pa-13. 4. When rabbit peripheral hlood was reacted with Pa-13 (5 X 107 microorganism/ml) for 1 hour at 37°C, phagocytic act ivity was found in 80.096 of polymorphonuclear leukocytes from OEP immune rabbit and 28.9% from normal rabbit 5. Number of viable P. aeruginosa was decreased to 6% after reacting with the OEP immune rabbit blood for 1 hour at 37°C, in contrast it was decreased to 77% in normal rabbit blood