Using immunohistochemical techniques, we studied IFN-γ-producing cells (IFN-γ-PC) in vivo during immune responses to thymus-independent type-2 (TI-2) Ag. Detection of IFN-γ-PC in cryostat sections of spleen-tissue was performed with an enzyme labeled mAb directed against IFN-γ. After TNP-Ficoll immunization, IFN-γ-PC and TNP-specific antibody-forming cells (TNP-AFC) displayed similar kinetics reaching a maximum number at day 5 to 7. The IFN-γ-PC were localized in the same compartment as TNP-AFC and a part of them in juxtaposition to TNP-AFC. Immunization with other TI-2 Ag resulted also in a significant increase of the number of IFN-γ-PC. In a parallel experiment we found both in vivo and in an ELISA-spot assay a significant increase of the number of IFN-γ-PC and IFN-γ-spot-forming-cells, respectively, in spleens of mice 6 to 7 days after TNP-Ficoll immunization. Double staining of spleen sections for IFN-γ and surface Ag revealed that 5 to 7 days after TNP-Ficoll immunization, ± 40% of the IFN-γ-PC expressed the MT4 Ag (CD4), ± 50% the Lyt-2+ Ag (CD8) and ± 10% the asialo-GM1 Ag (NK cell). This study represents the first description of the in vivo activity and characterization of IFN-γ-PC during a TI-2 immune response. Moreover, the presented data confirm suggestions from in vitro investigations that IFN-γ and T cells may play a direct role in the in vivo regulation of a primary immune response against a TI-2 Ag.
|Number of pages||8|
|Journal||Journal of Immunology|
|Publication status||Published - 1991|