A NEW ASSAY SYSTEM DETECTING ANTIBODY-PRODUCTION AND DELAYED-TYPE HYPERSENSITIVITY RESPONSES TO TRINITROPHENYL HAPTEN IN AN INDIVIDUAL MOUSE

A new assay system detecting antibody production and delayed-type hype rsensitivity (DTH) responses to trinitrophenyl hapten in an individual mouse (AS-DAD) was established. BALB/c mice were immunized intraperit oneally with varying amounts of 2,4,6-trinitrophenylated sheep red blo od cells (TNP-SRBC) on day 0. Venous blood was collected on days 2, 4, 6, 8 and 10. Levels of anti-TNP IgM and IgG in serum were assayed by enzyme-linked immunosorbent assay (ELISA). After series of bleeding th e mice were challenged with 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution in the footpad on day 14. Footpad swelling was measured 24 o r 48 h after the challenge. Peak responses of the anti-TNP IgM and IgG production were detected 4 or 6 days after the immunization with 10(9 ) TNP-SRBC. Maximum DTH response was also observed with 10(9) TNP-SRBC 24 h after the challenge on day 14. The antibody and DTH responses we re also induced in other normal inbred strains such as C3H/He and DBA/ I but not BALB/c nu/nu mice. To evaluate AS-DAD in immunopharmacologic al studies, various immunomodulating agents were examined in BALB/c mi ce by subcutaneous administration on days 0; 1, 2 and 3. Cyclosporin o r cyclophosphamide at 100 mg/kg/day completely inhibited not only the anti-TNP IgM and IgG production but also the TNP-specific DTH response . Prednisolone at 0.5 mg/kg/day had no significant effect on the IgM a nd Ige production, whereas it inhibited the TNP-specific DTH response. Interestingly, histamine-added mouse gamma-globulin at 150 mg/kg/day clearly enhanced the anti-TNP IgM and IgG production, while it showed a suppressive effect on the TNP-specific DTH response. Levamisole at 5 .0 mg/kg/day showed suppressive effects on the anti-TNP IgG production without affecting the IgM production and the DTH response. These resu lts suggest that AS-DAD is useful for evaluating the immunopharmacolog ical action ofvarious agents.