184 IMMUNOLOGY 



a number of pathological conditions such as hypertrophic cirrho- 

 sis of the liver, hemolytic jaundice, paroxysmal hemoglobinuria, 

 Raynaud's disease, and trypanosomiasis in man and animals. 



Cold Agglutinins. — The term ' ' cold agglutinins ' ' is used by Li 

 Chen-Pien (1926) and others to indicate autoagglutinins, but 

 Landsteiner (1928) considers any hemagglutinins that bring 

 about real agglutination only at low temperatures of either the 

 individual's own corpuscles or those of others of the same species, 

 "cold agglutinins." On the other hand, Snyder differentiates 

 ])etween autoagglutinins and cold agglutinins for he says, "When 

 the individual's red cells are agglutinated under such conditions 

 (0°-5° C.) by his own serum, the reaction is spoken of as 'auto- 

 agglutination.' When the agglutination occurs due to serum of 

 another individual, the reaction is known as 'cold agglutination.' 

 These two reactions are certainly related and may be identical." 

 Landsteiner 's views seem to be in harmony with the term "cold 

 agglutinins" and are hence recommended to the student as per- 

 haps the most satisfactory. 



PsEUDOAGGLUTiNATiON. — The phenomenon of pseudoagglutina- 

 tion occurs at low temperatures and may be intensified at 37° C. 

 It is due to rouleaux formation in which the red cells adhere to- 

 gether like piles of coins. The mechanism of rouleaux formation 

 does not involve agglutinins and hence is an entirely different 

 phenomenon from agglutination. Snyder (1929) says that the 

 tendency for rouleaux formation is frequently increased in "rheu- 

 matic fever, tuberculosis, pneumonia, cardiac diseases and in cer- 

 tain physiologic conditions such as menstruation and pregnancy" 

 or any condition showing an increase in the rate of sedimentation 

 of the red cells. 



Inhibition of Rouleaux Formation, — Snyder cites the work of 

 Lattes (1924) and Falgairolle (1926) who found that rouleaux 

 formation is inhibited by adding lecithin and other substances to 

 the serum. Snyder (1929) states that one part of kaolin to three 

 parts of serum will also inhibit rouleaux fonnation. He also 

 suggests the use of formalin and hypotonic salt solution. Shat- 

 tock (1900) noted that diluting the serum with saline prevented 

 pseudoagglutination. Rouleaux formation and true agglutina- 

 tion of red cells are illustrated in Figs. 8 and 9 respectively. 



