Abstract
This review presents and discusses our recent data on the use of somatic transgene immunization in the induction of CD4 T cell responses in vivo. Somatic transgene immunization is a process that targets B lymphocytes resident in the spleen with DNA coding for antigenized immunoglobulin H chain genes. After transgenesis B lymphocytes function as antigen-producing and antigen-presenting cells. The studies reviewed herein describe the characteristics of the primary and memory CD4 response against a dominant Th cell determinant. In addition, they show how ad hoc modifications of the transgene result in the induction of a CD4 T cell response against Th cell determinants against which a response is normally not obtained. The new concept Th-Th cooperation is discussed.