T helper 1 (Th1) and Th2 characteristics start to develop during T cell priming and are associated with an immediate ability to induce immunoglobulin class switching.

The respective production of specific immunoglobulin (Ig)G2a or IgG1 within 5 d of primary immunization with Swiss type mouse mammary tumor virus [MMTV(SW)] or haptenated protein provides a model for the development of T helper 1 (Th1) and Th2 responses. The antibody-producing cells arise from cognate T cell B cell interaction, revealed by the respective induction of Cgamma2a and Cgamma1 switch transcript production, on the third day after immunization. T cell proliferation and upregulation of mRNA for interferon gamma in response to MMTV(SW) and interleukin 4 in response to haptenated protein also starts during this day. It follows that there is minimal delay in these responses between T cell priming and the onset of cognate interaction between T and B cells leading to class switching and exponential growth. The Th1 or Th2 profile is at least partially established at the time of the first cognate T cell interaction with B cells in the T zone. The addition of killed Bordetella pertussis to the hapten-protein induces nonhapten-specific IgG2a and IgG1 plasma cells, whereas the anti-hapten response continues to be IgG1 dominated. This indicates that a Th2 response to hapten-protein can proceed in a node where there is substantial Th1 activity.

Demonstration by labeled treponemal antigen of specific antibodies in the tissue infiltrates of secondary syphilis.

Specific antitreponemal antibodies have been demonstrated by immunofluorescence techniques in the lymphoplasmocytic infiltrates which characterize early symphilitic lesions. A purified suspension of Nichols strain Treponema pallidum was sonified and labeled with fluorescein isothiocyanate and applied to cryostat sections of 12 biopsy specimens from the cutaneous lesions of 11 patients with proven secondary syphilis, using a modified direct immunofluorescence procedure. Specimens from various inflammatory dermatoses processed similarly served as controls. Granular fluorescence was noted in the dermis in 9 of the 12 specimens corresponding to areas of heavy plasma cell infiltration and some fluorescence was found directly on plasma cells which were identified by subsequent hematoxylin and eosin staining. This fluorescence could be blocked by prior incubation of the sections with unlabeled sonified treponemal suspension. Control slides did not reveal any fluorescence. The use of labeled treponemal antigen may aid the tissue diagnosis of early syphilitic lesions which can mimic a variety of dermatological disorders.