ANTI-ENZYME IMMUNITY 269 



of Clostridia resemble those of staphylococci and stand in sharp contrast 

 to that of Streptococcus hetnolyticus. A recent brief survey on the pro- 

 duction of lytic factors by various bacteria is reported by Lewis, et al. 

 (1949).* 



d. Fibrinolytic Factor and Bacterial Invasiveness. The possible 

 role of bacterial fibrinolytic factor in the invasiveness of Streptococcus 

 pyogenes has been variously considered. It has been suggested that this 

 factor aids the lysis of clots formed in an inflamed area, thus permitting 

 the infiltration of the invasive agent through damaged tissue into the 

 blood stream. According to Dennis and Berberian (1934) those strains 

 of streptococcus which elaborate fibrinolytic factor are able to invade 

 and cause more serious conditions such as septicemia. And those strains 

 (Streptococcus viridans') which are unable to elaborate this factor lack 

 invasiveness. It may be that these explanations of the role of fibrinolytic 

 factor represent certain of the events that take place when an infection 

 takes the proportion of a septicemia. However, the processes of inflam- 

 mation and invasiveness are too complex to permit a well-defined bio- 

 chemical role, at present, to one particular factor. Our information 

 concerning the role of various factors are as yet too meagre to define the 

 role of each factor specifically. 



e. Antibody to Fibrinolytic Factor. It is a known fact that the sera 

 of patients convalescing from streptococcal infection contain specific 

 antibodies which neutralize the function of fibrinolytic factor in fi- 

 brinolysis. Massell, et al. (1939) and Mote, et al. (1939) claimed that 

 there are differences in the structure of fibrinolytic factors from differ- 

 ent strains causing the formation in vivo of structurally different anti- 

 fibrinolysins. Should this be true, it would mean that the fibrinolytic 

 factors are strain specific. An extensive quantitative study of a great 

 many streptococcal strains by Kaplan (1946) contradicts the strain 

 specificity of fibrinolytic factors. 



In a report based on a study of 404 well soldiers and 808 men ad- 

 mitted to the respiratory wards of the hospital, the U. S. Army Com- 



*0f the bacterial lytic factors (fibrinolysins) those of the ^-hemolytic streptococci 

 are most extensively studied. The presence of lytic factors in other species of bacteria 

 are of interest, but cannot, at present, be safely stated to be similar in action to 

 streptococcal fibrinolysin. The question of whether or not the lysis of fibrin clots 

 occurring with the participation of the culture filtrates of other species of bacteria 

 is due to proteolytic enzymes, or to non-proteolytic factors cannot at present be 

 answered. The answer must come from a study of the properties of at least partially 

 purified preparations. 



