SARCOIDOSIS 



bacillus. He found that when tubercle bacilli could be 

 isolated from cases of sarcoidosis, they were of human type 

 with normal virulence for guinea-pigs. Further, Pyke and 

 Scadding (1952) and Citron and Scadding (1957) have shown 

 that many sarcoid cases resemble cases of tuberculosis de- 

 sensitized by tuberculin, in showing a positive Mantoux 

 reaction to tuberculin + cortisone but not to tuberculin alone. 



The immunological interpretation of the situation would 

 perhaps be in some such terms as the following: 



The basic genetic character by which the individual differs 

 from the normal is almost the converse of agammaglobu- 

 linaemia. There is an abnormally efficient production of 

 classical antibody and a poor development of the antibody- 

 carrying cells (lymphocytes presumably) responsible for 

 Mantoux reaction and the other manifestations of hyper- 

 sensitivity. The result of tuberculous infection in such a 

 person would in most instances be expected to be overcome 

 without symptoms. On our hypothesis, the only way in 

 which a lesion would develop is by the tubercle bacillus 

 taking on the low-grade protoplast form and behaving 

 virtually as a persisting virus multiplying only sufficiently 

 to keep more or less in pace with the cells that contain it. 

 Rarely reversion to the classical form of the tubercle bacillus 

 may occur; more often the condition gradually eliminates 

 itself; and very rarely a widespread fatal semi-malignant 

 condition ensues. 



(ii) The second alternative is that usually in the course of 

 a tuberculous process, but sometimes perhaps independently, 

 a low-grade virus, possibly resembling lymphogranuloma 

 inguinale virus (LGV), infects the mesenchymal cells and 

 thereafter behaves as the hypothetical protoplast of (i) . There 

 is no positive evidence of the existence of such a virus. 



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