Enhanced induction of the IgA response in pigs by calcitriol after intramuscular immunization

Abstract

In this study, the immunomodulating effect of two steroid hormones namely 1,25-dihydroxyvitamin D 3 [1,25(OH) 2D 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 μg of 1,25(OH) 2D 3, 40 μg of DHEA or the combination of both steroids. 1,25(OH) 2D 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) 2D 3 group. Furthermore, 1,25(OH) 2D 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) 2D 3 on the IgA response. In conclusion, 1,25(OH) 2D 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.