T-LYMPHOCYTES ARE NOT THE TARGET FOR ESTRADIOL-MEDIATED SUPPRESSION OF DTH IN RECONSTITUTED FEMALE SEVERE COMBINED IMMUNODEFICIENT (SCID) MICE

Oestrogen has the capacity to suppress T cell-dependent DTH. To explor e the mechanisms whereby oestrogen exerts its effects on the immune sy stem we have used SCID mice which are largely devoid of functional T a nd B lymphocytes, hence being unable to raise DTH, but display intact antigen-presenting capacity. Transfer of lymphocytes to SCID mice rest ores the DTH capacity. In order to analyse if oestrogen down-regulates DTH by a direct action on T cells we reconstituted SCID mice with eit her splenocytes or thymocytes from congenic C.B-17 or allogeneic B6 do nor mice. Either donor or recipient mice were exposed to estradiol bef ore cell transfer. DTH response was registered in recipient SCID mice 1 and 3 weeks after challenge with oxazolone (OXA). SCID mice receivin g estradiol-exposed spleen cells from congenic or allogeneic donor mic e displayed lower DTH responses compared with control mice. In contras t, SCID mice receiving estradiol-exposed thymocytes from congenic dono r mice showed no significant difference in DTH response compared with control mice. Estradiol-treated SCID mice, transferred with either spl een cells or thymocytes from congenic, hormonally non-treated donors, displayed a significantly lower DTH response compared with control mic e. In contrast, estradiol-treated SCID mice receiving hormonally non-t reated allogeneic spleen cells showed no difference in DTH response co mpared with control mice. The results show that T lymphocytes are not the target cell population for estradiol-mediated suppression of DTH i n reconstituted female SCID mice.