The overall objective of these studies is to determine the structural character of idiotype(id)-anti-id networks and establish their influence on normal immune responses. Studies will utilize as models the two cross-reactive id(CRI) families (5AF6 and 3C6) assocated with the BALB/c antibody response against the p-azophenylarsonate-(Ar) hapten. Sepcific aims are: (1) to determine the Id expression of early in vivo antigen-driven anti-Ar Beta cells compared to id produced in vitro by cloned anti-Ar Beta cells expanded independent of antigen and with id produced in antigen-driven in vitro cultures. This will provide an understanding of id expression and a basis for pursuing Aim #2. (2) Expand in vitro and clone anti-id Beta cells derived from normal, id-primed and antigen-primed BALB/c mice and examine their frequency, specificity, and influence. To determine if cloned anti-id Beta cells can recolonize in vivo and influence normal id expression in response to subsequent antigen stimulation. (3) To probe the anti-di repertoire by producing isologous monoclonal anti-id antibodies specific for the 5AF6 id family dervied from cloned anti-id Beta cells (Aim #2) and overt immunization with id and characterize them immunochemically for their specificity, heterogeneity and their in vivo regulatory influences on id production. Specific efforts will be made to stimulate and recover monoclonal anti-id reactive with idiotopes shared between 5AF6 family anti-Ar and id(+) immunoglobulins(Ig) not having anti-Ar specificity termed 'parallel id' sets and determine the regulatory impact of such network related parallel id in normal immune responses. Additionally, efforts will be made to elicit, recover, and characterize monoclonal anti-id that bind id because they bear a variable region 'internal image' of the Ar hapten. These studies should establish the significance of 'parallel id' and 'internal images' in network immunoregulation. (4) Contingent on molecular studies, this Aim will determine the mechanism of depressed 5AF6 and 3C6 id expression associated with Ig light chain(Vk) and T cell alloantigen(Lyt3)-linked genes. This is a novel association between id regulation and these genetic loci. Together these aims address fundamental questions of how and to what extent id-anti-id Beta cell networks influence self regulation of the immune system.