INFLAMMATION AND LEUCOCYTE RESPONSE 59 



,<>iant cells but think tlicy arc formed by mitosis and increase in 

 cytoplasm. There is no blood supply extending into the mass or 

 tubercle. 



A mantle of granulation tissue due to connective tissue prolifera- 

 tion forms about the mass of mononuclear cells forming the tubercle. 

 Small mononuclear cells resembling lymphocytes tend to collect in 

 and about the outer elements of tlie mantle of granulation tissue. 



Tubercle Phospflvtid and Cell Stimulation.- — Sabin and Doan 

 (1927) report that Anderson's phosphatid fraction of the tubercle 

 bacillus will cause ''decided proliferation of monocytes, epithelioid 

 cells, and giant cells leading to a massive formation of tubercular 

 tissue." 



Varieties of the Tubercle Bacillus. — Winn and Petroff* 

 (1932) have obtained four interesting variants which they call 

 S, F.S., R and Ch. dissociated from an avian tubercle bacillus 

 W They state that these variants show different physical and 

 chemical properties and elicit different tissue responses in the host. 

 They summarize their results as follows : 



''The leucocyte response in S and F.S. is of an acute type wiiile 

 that produced by R and Ch. variants is indicative of a chronic, 

 healing tuberculosis. 



''The tubercle formed Iw S is of an acute toxic type, the F. S. 

 more of a foreign body type and that of R and Ch. relatively benign. 



"The S variant is by far the most virulent and is closely fol- 

 lowed by the F. S. type. The R and Ch. variants are comparatively 

 avirulent." 



Dev-elopment of Hypersensitiveness. — Primary infection with 

 the tubercle bacillus renders the animal hypersensitive to tuber- 

 culin. This state of hypersensitiveness is responsible for the vio- 

 lent inflammatory reaction around new and latent foci of infection 

 which develops when reinfection with tubercle bacilli occurs or 

 when a normally nontoxic dose of tuberculin is injected into an 

 infected animal. It is responsible also for many systemic symp- 

 toms which are known to be pathognomonic of tuberculosis. 



Tissue Response to Viruses. — In regard to virus disease one is 

 dealing with infectious agents that enter the cells of the host and 



•Winn, W. A., and Petroff, S. A.: J. Expor. Med. 57: 239, 1932. 



