ANDREWES 



evidence suggests that there is a non-specific element in immunity. 

 It is generally agreed that in isolated communities immunity to colds 

 falls, so that contact with civilization after along interval is quickly 

 followed by colds, and often they are severe ones. Why? The usual 

 explanation is that people in a large community are constantly sub- 

 jected to little doses of virus which reinforce their immunity, often 

 without giving rise to any symptoms. Yet if there are 150 or 57 or 

 some other large number of cold viruses, it is unlikely that we are 

 all being regularly exposed to all of them. If not, why are we so 

 much more resistant than these lately- isolated people? And why 

 don't they get 57 colds when they beginto mix with society? It seems 

 that if there is a nonspecific as well as a specific immunity, the 

 facts couldbereasonablyexplained. This could be mediated by inter- 

 feron, a virus- inhibiting protein produced by cells under the stimu- 

 lus particularly of dead or damaged virus. Its production seems to 

 supply a quickly acting method of halting a virus infection until anti- 

 bodies canbe made and mobilized. Its action is local and nonspecific, 

 being directed not merely against the virus which evoked it. In tis- 

 sue-culture, rhinoviruses are amongst those most susceptible to its 

 action, and the Salisbury workers are at present engaged on studies 

 in volunteers of a possible role of interferon in cold virus infections. 



If I had to offer a working hypothesis as to the effect of cold in 

 favouring colds, it would be along the following lines. The human 

 body, especially the respiratory tract, is exposed to large environ- 

 mental changes. The complicated anatomy of the nose is part of a 

 homeostatic mechanism designed to protect the lungs from sudden 

 changes. But it may not operate completely and instantaneously. 

 There may be a lag, and during an "unguarded hour", a virus reach- 

 ing or already inthe mucosa,in equilibrium with the host,may snatch 

 its chance. I doubt whether a local fall in temperature alone suf- 

 fices; it may well be an indirect consequence of temperature fall. 

 Some evidence suggests that interferon production is not so good at 

 lower temperatures, and that is the sort of thing about which I am 

 speaking. 



I regard an attack on this difficult matter as the most important 

 phase of our war against respiratory infection. Injecting vaccines 

 against dozens of sero- types of virus seems to be a rather unprom- 

 ising business. Discovery of the relation between cold and colds 



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