Monoclonal anti-idiotypic antibody functionally mimics the human gastrointestinal carcinoma epitope GA733

Abstract

Anti-idiotypic antibodies (Ab2) that bind to the antigencombining region of anti-tumor antibodies (Ab I) may functionally, and even structurally, mimic tumor antigen. We have previously demonstrated that polyclonal goat Ab2 directed against anti-human gastrointestinal carcinoma Ab I GA733 induces anti-anti-idiotypic antibodies (Ab3) in animals that are Ab I -like in their binding specificity and idiotope expression. To obtain more defined Ab2 vaccines with potentially increased specificity and efficacy, a monoclonal Ab2 (FG I) was produced against Ab I GA733 in rats. The monoclonal Ab2 FG I, similar to the polyclonal Ab2 described previously, induced Ab3 in rabbits that were Ab I -like in their idiotope expression and binding specificity to tumor cells and antigen. Antigen-specific Ab3 induced by Ab2 FG I were easily detected in unprocessed rabbit sera, whereas the demonstration of such Ab3 after polyclonal Ab2 immunization required purification of the Ab3 from the rabbit sera. In addition, Ab2 FG I induced antigen-specific humoral and cellular immunity in mice. Murine Ab3 bound specifically to antigen-positive tumor cells. Ab2-immunized mice showed antigen-specific delayed-type hypersensitivity (DTH) reaction, and cultured splenocytes from the immune mice demonstrated specific proliferation and cytokine (interferon-y and interleukin-4) secretion upon stimulation with GA733 antigen. However, immune mice were not protected against a challenge with syngeneic GA733 antigen-expressing colon carcinoma cells.o 1996 Wiley-Liss, Inc.

Inhibition of tumor growth by recombinant vaccinia virus expressing GA733/CO17-1A/EpCAM/KSA/KS1-4 antigen in mice

“…15 -18,21 However, singleepitope Ab2 vaccines and extracellular domain GA733-2E protein are expected to induce less potent antitumor immunity compared to full -length Ag vaccines, which express multiple, potentially immunogenic epitopes. Thus, Ab2 mimicking the GA733 epitope 26 and extracellular domain protein GA733 -2E 19 did not protect mice against challenge with CT26 -GA733 -2 tumor cells, in marked contrast to the significant antitumor effects of VV GA733 -2 described here and Ad GA733 -2 described previously, 30 which both express full -length GA733 Ag.…”

“…CT-26 -GA733 -2 and CT-26 -ASEN ( control ) transfectants have been described. 26 Murine P815 mastocytoma cells, murine Yak natural killer target cells, and human SW1116 CRC cells were obtained from American Type Culture Collection ( ATCC, Rockville, MD ). Melanoma cell line WM9 has been described.…”

“…31 Lymphocyte stimulation and proliferation assay Lymphocyte proliferation assays were performed as described. 26 Regional lymph nodes from immunized mice were removed and cell suspensions were prepared. Cells were stimulated at 1Â10 5 /well/0.2 mL of RPMI -1640 medium ( Gibco BRL; supplemented with 10% FBS, 50 g/mL gentamycin, 2Â10 À 5 M 2-mercaptoethanol, 10 mM HEPES, and 2 mM L -glutamine ) with different concentrations ( 20 and 5 g/mL ) of native full -length GA733 Ag or with 10 5 UV-irradiated splenocytes infected with 10 7 PFU of VV GA733 -2 or VV for 3 days.…”

Addition of interleukin-12 to GA733 tumor protein vaccine leads to development of tumor protective immunity despite surgical stress

“…Initially, GA733-transfected CT26 murine colon adenocarcinoma cells [8,9] were cultured in complete Iscove's medium. Before inoculation, C26 cells were harvested and washed several times.…”

Redirected cellular cytotoxicity by infection of effector cells with a recombinant vaccinia virus encoding a tumor-specific monoclonal antibody

“…22,23 Murine RMA cells (C57BL/6 mouse T-cell lymphoma; American Type Culture Collection, Manassas, Va; (H2D b )) were used to stimulate murine CTLs.…”