VIII 



THE PATHOLOGY OF THE 

 IMMUNE RESPONSE 



There is a large and important group of disease states whose 

 essential pathogenesis seems to be related to malfunction of 

 the mechanism of immunity. These can be divided into 

 five main groups. 



(i) The allergic diseases in which there is clear evidence 

 that the responsible antigen is some substance extrinsic to 

 the body, whether it is a chemical, a migrating helminth, 

 grass pollen or house dust. This group has its own special 

 problems and will not be discussed further in this chapter. 



(ii) The so-called collagen diseases characterized histologi- 

 cally by fibrinoid degeneration of connective tissues in various 

 parts of the body and including rheumatic fever, rheuma- 

 toid arthritis, disseminated lupus erythematosus, poly- 

 myositis and dermatomyositis, scleroderma and lupoid 

 hepatitis. 



(iii) Primary and secondary haemolytic anaemia of auto- 

 immune type, that is, showing a positive direct Coombs test 

 with which can be included auto-immune thrombocytopenic 

 conditions. 



(iv) Hashimoto's disease — sub-acute thyroiditis or lymph- 

 adenoid goitre, which is the only fully established auto- 

 immune disease in the strict sense of the term. Other con- 

 ditions such as sympathetic ophthalmia may eventually also 

 be included here. 



(v) Congenital agammaglobulinaemia is in a different 

 category, but it is, of course, of the greatest interest to any 

 basic consideration of immunological theory. Of special 

 interest in the present context is the fact that changes 

 resembling those of rheumatoid arthritis are common in 



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