Here we report further data of LPS-mediated signal transduction responsible for Escherichia coli phagocytosis. We demonstrate that both adhesion of hemocytes to substrata and LPS stimulation can cause activation of p44 MAPK in Ceratitis capitata hemocytes but with distinct kinetics indicating different functions. In addition, we showed that Drk, a homolog protein to the mammalian GRB2, is implicated in the transmission of LPS signaling, indicating that the Ras/mitogen-activated protein kinase pathway is involved. Either the cell-free or the cell-associated LPS appears to attach to the hemocyte surface by the same mechanism that is based on the cross-linking of LPS to membrane-associated p47 via the intermediacy of tyrosine derivatives generated by the action of phenol oxidase. By contrast, the cell-free LPS internalization into the hemocytes differs from the cell-associated LPS internalization. For E. coli internalization integrin receptors as well as cytoskeletal rearrangements are required, as judged by inhibition of E. coli internalization in the presence of the RGD peptide, ␤ 3 -integrin antibodies, and cytochalasin D.

The human HER-2/neu gene encodes a 185 kDa transmembrane glycoprotein recognized by MHC class I-restricted CTLs. Here, we report that HER-2/neu peptide CTL epitopes can also be recognized by cytotoxic NK-T lymphocytes. Unfractionated peptides derived from HLA-A2 Key words: natural killer T cells; cytotoxicity; cancer immunotherapy; HER-2/neu peptides; ovarian cancerCTLs recognize antigenic peptides, 8 -12 amino acid long, presented to them by professional APCs in the context of MHC class I molecules. 1 Such CTLs possess memory and can respond upon rechallenge by the same antigenic stimulus. Consequently, if induced by a tumor peptide vaccine, CTLs could provide longterm immunity. 2 Thus, definition of CTL peptide epitopes from tumor-associated antigens is an essential step toward the development of specific CTL-based cancer immunotherapy.It is now well established that CTLs recognizing human neoplastic cells can be isolated from PBMCs and tumor-infiltrating lymphocytes. 3 Such CTLs have been useful for identifying several genes encoding tumor antigens, which can be classified in the following groups: 3-5 (i) melanocyte differentiation antigens expressed on most melanoma cells and melanocytes but not on tumors from other tissues (e.g., tyrosinase, gp100, Melan-A/ MART-1); (ii) MAGE, BAGE and GAGE antigens expressed in several tumors of distinct histology but not in normal tissue except testis; (iii) unique, nonpublic tumor antigens generated by point mutations in widely expressed genes (e.g., cyclin-dependent kinase-4, ␤-catenin); and (iv) mutated (e.g., p53, k-ras), translocated (e.g., bcr-abl) and overexpressed (e.g., HER-2/neu) oncogenic proteins. Human therapeutic vaccine trials utilizing immunogenic CTL peptide epitopes are ongoing. 6 -9 While most of the focus in cancer immunology is on classical CD3 ϩ CD56 -CTLs, accumulating evidence suggests that CD3 ϩ cells coexpressing the NK cell marker CD56 display strong antitumor cytotoxic activity. Such cells normally comprise a small percentage of human PBLs (approx. 3%) and can be expanded in vitro in the presence of specific cytokine combinations. 10 Similar to lymphokine-activated killer cells, CD3 ϩ CD56 ϩ cells lyse their targets in a non-MHC-restricted manner but have demonstrated superior activity over lymphokine-activated killer cells since they show higher proliferation rates 11 and exert higher antitumor cytotoxic activity per culture, 11 higher purging activity against malignant cells derived from patients with chronic myelogenous leukemia 12 and higher cytotoxicity in a xenotransplant model. 13 A significant percentage of these CD3 ϩ CD56 ϩ cells did coexpress the CD8 antigen and this population was also highly cytotoxic. 13 In another report, 14 a melanoma peptide-specific, HLA-A2-restricted CTL clone of the same phenotype (i.e., CD3 ϩ CD56 ϩ CD8 ϩ ) appeared to belong to this subset of cells as it demonstrated both CTL and NK lytic ability.ACE isolated from tumor cell lysates contains peptides capable of specifically stimulating both CD4 ϩ and CD...

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A doublet of medfly hemocyte proteins with a molecular mass of about 55 and 50 kDa were precipitated with LPS. Antibodies raised against human CD14 recognize the same doublet of proteins. These results support that mammalian CD14 and the doublet of protein bands in medfly hemocytes share common epitopes. This doublet of protein bands is released from hemocytes upon LPS triggering. A portion of the released protein is clustered on the surface of a distinct hemocyte type and the other remains soluble. The membrane-bound LPS-binding protein is involved in LPS internalization and Escherichia coli phagocytosis but not in LPS signaling.