Interleukin-12 Is Capable of Generating an Antigen-Specific Th1-Type Response in the Presence of an Ongoing Infection-Driven Th2-Type Response

Abstract

Previously we demonstrated that recombinant murine interleukin-12 (rmIL-12) administration can promote a primary Th1 response while suppressing the Th2 response in mice primed with 2,4,6-trinitrophenyl–keyhole limpet hemocyanin (TNP-KLH). The present studies examined the capacity of rmIL-12 to drive a Th1 response to TNP-KLH in the presence of an ongoing Th2-mediated disease. To establish a distinct Th2 response, we used a murine model of leishmaniasis. Susceptible BALB/c mice produce a strong Th2 response when infected with Leishmania major and develop progressive visceral disease. On day 26 postinfection, when leishmaniasis was well established, groups of mice were immunized with TNP-KLH in the presence or absence of exogenous rmIL-12. Even in the presence of overt infection, TNP-KLH-plus-rmIL-12-immunized mice were still capable of generating KLH-specific gamma interferon (IFN-γ) as well as corresponding TNP-specific immunoglobulin G2a (IgG2a) titers. In addition, the KLH-specific IL-4 was suppressed in infected mice immunized with rmIL-12. However, parasite-specific IL-4 and IgG1 production with a lack of parasite-specific IFN-γ secretion were maintained in all infected groups of mice including those immunized with rmIL-12. These data show that despite the ongoing infection-driven Th2 response, rmIL-12 was capable of generating an antigen-specific Th1 response to an independent immunogen. Moreover, rmIL-12 administered with TNP-KLH late in infection did not alter the parasite-specific cytokine or antibody responses.

The combination of plasmid interleukin‐12 with a single DNA vaccine is more effective than Mycobacterium bovis (bacille Calmette–Guèrin) in protecting against systemic Mycobacterim avium infection

“…rIL-12 is capable of generating an antigenspecific Th1-type response in the presence of an ongoing infection-driven Th2-type response. 14 It is possible that a therapeutic vaccine consisting of IL-12 with appropriate mycobacterial antigens may promote Th1 T-cell responses in subjects with established lepromatous leprosy and so assist in the clearance of the infection…”

The intramembrane protease Sppl2a is required for B cell and DC development and survival via cleavage of the invariant chain

“…Mice were immunized intraperitoneally with 25 µg TNP-Ficoll or 100 µg DNP-KLH (Biosearch Technologies) in ALUM (Thermo Fisher Scientific). Levels DNP or TNP-specific Ig were assayed by ELISA as described previously (Schopf et al, 1999). HRP-conjugated rat anti–mouse IgM, IgG1, and IgG3 were purchased from BD.…”

T helper differentiation in resistant and susceptible B7-deficient mice infected with Leishmania major

“…g/ml gentamicin (Sigma Chemical Co., St. Louis, MO), 10 mmol/l Hepes (Sigma), and 10 mmol L-glutamine (Life Technologies, Grand Island, NY) in rabbit blood agar flasks [36]. Soluble leishmanial antigen (SLA) preparations for the determination of parasite-specific serum immunoglobulin titers and in vitro restimulation of lymph node T cells were generated as described [37].…”

“…In each experiment three to five wt, B7-1 -/-, B7-2 -/-, CD28 -/-, and B7 dko 129 or BALB/c mice were infected with 2×10 5 stationary-phase L. major promastigotes in both rear footpads [37]. Footpad swelling was subsequently measured once a week for 7 weeks with a dial caliper.…”

“…Sera from L. major-infected mice were analyzed in an SLAspecific antibody isotype ELISA to determine the titer of IgG 1 and IgG2 a . The protocol for this colorimetric ELISA has been described previously [37] and employs horseradish peroxidase (HRP)-conjugated rabbit anti-mouse IgG 1 or IgG 2a (Zymed, San Francisco, CA) to detect the relevant immunoglobulin isotype.…”