In this study, the immunomodulating effect of two steroid hormones namely 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] and dehydroepiandrosterone (DHEA) was examined on the antigen-specific antibody responses by intramuscular immunization of pigs with human serum albumin alone (HSA) or supplemented with 2 microg of 1,25(OH)(2)D(3,) 40 microg of DHEA or the combination of both steroids. 1,25(OH)(2)D(3) significantly enhanced the antigen-specific IgA and IgM serum response. Higher HSA-specific IgA titers were also found in the mucosal secretions (saliva, feces and nasal) of the steroid treated animals, especially in the 1,25(OH)(2)D(3) group. Furthermore, 1,25(OH)(2)D(3) and DHEA increased the number of antigen-specific IgA and IgG antibody-secreting cells in the local draining lymph nodes, but only low numbers were detected in lymph nodes draining the mucosa. DHEA decreased the IgM serum response and had a tendency to enhance the IgG2 and IgG serum responses. Strong and comparable IgG, IgG1 and IgG2 serum responses were seen in all groups. Combining both steroids did not result in a higher IgA serum response. On the contrary DHEA seems to neutralize the effect of 1,25(OH)(2)D(3) on the IgA response. In conclusion, 1,25(OH)(2)D(3) significantly enhanced the antigen-specific IgA and IgM response in serum and the number of antigen-specific IgA and IgG ASC in the local draining lymph nodes following intramuscular immunization.