the possibility that the antigen-presenting `` '' macrophages '' '' interacting with helper cells either directly or via the intermediary action of a soluble factor consisting of ia antigen and a fragment of immunogen , termed grg ( genetically related factor ) , are a site of ir gene action was investigated by using the synthetic polypeptide antigen ( t , g ) -a -- l .
C0003320
f immunog
C0301872
f