ANAMNESTIC RESPONSES 



ing injection of an influenza A vaccine, his serological 

 response depends mainly on what ' family ' of influenza A 

 viruses he first encountered. People in their fifties at the 

 present time give a response to the antigen we call ' Swine ' 

 which we believe was characteristic of the virus responsible 

 for the 1918-19 pandemic. Young men in their twenties 

 respond with antibody against PRS type current in the 

 thirties and children to type FMi which emerged in 1946. 

 Today's babies will presumably be stamped with the mark 

 of Asian A influenza for the rest of their lives. There are many 

 minor discrepancies in individual reactions but the general 

 pattern is fully established. 



Suppose we consider a person who has been exposed to 

 three successive ' families ' of influenza A virus ; we can give 

 these viruses the antigenic formulae ABCD, ABEF, AEGH. 

 As a result of the first infection, antibody sites a, b, c and d are 

 available in one form or another. The response to the entry 

 of antigen AEGH is to call forth again a h c and ^, with 

 perhaps small amounts of ^^ and h. This could be represented 

 conventionally by assuming that cells carrying a also carry 

 h c and d^ so that stimulation by A results in the rephcation 

 of cells which will provide antibody more equivalent to 

 ABCD than to the actual infecting antigen AEGH. This is the 

 simplest formal explanation but other variants of the same 

 theme could be devised. 



A related finding from Jensen et al. (1956) has a similar 

 form but introduces a further complication. If an animal is 

 successively immunized with strains ABCD (i), ABEF (2) 

 and AEGH (3) and the antibody titres examined, the result 

 will be as shown in Figure 9. Now if the final serum is ab- 

 sorbed with each of the three strains, the important result 

 is that strain ( i ) alone is capable of absorbing out all the 

 antibodies against (i), (2) and (3). 



If we examine this result in terms of the clonal selection 

 theory, we must assume that the clones concerned were 

 sorted out by ABCD and can be represented as a, ab, acd, ab, 



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