Studies of the mechanisms for the induction of in vivo tumor immunity. VI. Induction of specific and nonspecific cell-mediated immunity in tumor-bearing hosts and its correlation with transplantation tumor immunity

Studies were performed to determine the development of cell-mediated cytotoxic response at tumor site in C57BL/6 mice bearing progressively growing FBL-3 ascites leukemia. The effectors isolated from tumor ascites are found to be highly cytotoxic for leukemic target cells. The levels of cytotoxicity obtained with effectors isolated from tumor site are generally higher than those obtained with immune mice. This cytotoxicity is both specific and nonspecific. The specific cytotoxicity against tumor-associated antigen is mainly mediated by T cells and the nonspecific cytotoxicity against unrelated tumor cells is mediated largely by macrophages. The T-cell-enriched preparation did not give significant natural killer activity. When testing the ability of these effectors to produce in vivo immunity against the challenge of FBL-3, it was found that only T cells could confer the transplantation-type immunity, but the immunity was transient. The macrophage-enriched preparation isolated from tumor ascites failed to give in vivo protection. These findings indicate that in FBL-3 system, mice with progressively growing tumors are able to develop immune response against tumor cells. However, this immunity is probably interfered with by a suppressor factor(s) or suppressor cells which restrict their activity to eliminate the tumor cells effectively.     

Localization of vimentin,the nonspecific intermediate filament protein,in embryonal glia and in early differentiating neurons: In vivo and in vitro immunofluorescence study of the rat embryo with vimentin and neurofilament antisera

Antisera raised against vimentin, the protein subunit of nonspecific intermediate-sized filaments (IFs), were used in conjunction with neurofilament (NF) antisera to study the early development of neurons and glia in the rat embryo. Vimentin-positive fibers spanning the entire thickness of the neural tube including the cerebral vesicles were first observed on Day 12, concomitant with the appearance of NF protein in more confined areas (anterolateral regions of spinal cord and brain stem; motor roots emerging from the NF-positive areas). From Day 15 onwards vimentin and NF antisera selectively decorated glia and neurons, respectively, both in vivo and in vitro. Before Day 15 it appeared that NF-positive structures also stained with antivimentin in cryostat sections. In vitro experiments confirmed the presence of vimentin in early differentiating neurons. NF-positive cells were observed which also reacted with antivimentin in cultures obtained from 13- and 14-day embryos, but not later in development. Most neurons in these cultures became vimentin negative after 2–3 days in vitro.     

Characterization of the calmodulin binding domain of neuromodulin. Functional significance of serine 41 and phenylalanine 42.

Neuromodulin (also designated P-57, GAP-43, B-50) is a major presynaptic substrate for protein kinase C. Phosphorylation of neuromodulin decreases its affinity for calmodulin, suggesting that neuromodulin may function to bind and concentrate calmodulin at specific sites within neurons, releasing calmodulin locally in response to phosphorylation by protein kinase C (Alexander, K. A., Cimler, B. M., Meier, K. E., and Storm, D. R. (1987) J. Biol. Chem. 262, 6108-6113). In the present study, we have constructed and characterized several mutant neuromodulins to demonstrate that the amino acid sequence 39-56 is required for calmodulin binding, and that this domain contains the sole in vitro protein kinase C phosphorylation site at serine 41. We also demonstrate that the adjacent phenylalanine 42, interacts hydrophobically with calmodulin. These hydrophobic interactions may be disrupted by the introduction of negative charge at serine 41, and thereby regulate the neuromodulin/calmodulin binding interactions. The sensitivity of the neuromodulin/calmodulin binding interaction to negative charge at serine 41 was determined by substitution of serine 41 with an aspartate or an asparagine residue. The asparagine mutant retained its affinity for calmodulin-Sepharose while the aspartate mutant did not adsorb to calmodulin-Sepharose. We conclude that protein kinase C phosphorylation of neuromodulin abolishes calmodulin binding by introducing negative charges within the calmodulin binding domain at a position adjacent to the phenylalanine.     

The organization of the gene for the human cerebroside sulfate activator protein

The organization of 14 exons covering 97% of the cDNA sequence of human cerebroside sulfate activator protein precursor has been determined from two overlapping EMBL-4 human genomic clones extending over 17kb. All exons and exon/intron splice junctions and five introns were sequenced. Exon 8 consists of only 9 bp and is involved in alternative splicing which generates three different mRNAs of cerebroside sulfate activator precursor.     

Incidence of toxigenic vibrios in foods available in Taiwan.

A total of 1088 vibrios and related species were isolated from seafood and aquacultured foods available in Taiwan. They were identified as Vibrio alginolyticus, V. cholerae, V. fluvialis I, V. fluvialis II, V. parahaemolyticus, V. mimicus, Aeromonas caviae, A. hydrophila, A. sobria and other species. Incidence of these Vibrio and Aeromonas species in these foods was high. Vibrio parahaemolyticus was frequently found in seawater and in foods of freshwater origin. The Vibrio isolates were examined for enzymatic and toxigenic activities. Most of them showed strong lipase or protease activities. Haemolytic activities of V. cholerae, V. fluvialis I and V. fluvialis II isolates were mostly strong. About 49% showed cytotoxic activity and 5% cytotonic activity in Chinese hamster ovary cell culture assay. Nevertheless, only three non-O1 V. cholerae (2.07%) and two V. parahaemolyticus isolates (1.65%) produced cholera toxin and thermostable direct haemolysin activity, respectively. Various toxigenic vibrios may be important food-borne pathogens in this region because of their high incidence in foods.     

IL-4 regulation of a protein kinase C independent pathway for the generation of alpha CD3-induced activated killer cells.

alpha CD3 induced the generation of activated killer cells from resting T cells. Pretreatment of the splenic responders with PMA, a phorbol ester, depleted protein kinase C and induced unresponsiveness to the generation of alpha CD3-induced activated killer (CD3-AK) cells. Addition of exogenous IL-4 (1 U/ml) restored the cytotoxic response, with the maximal effect achieved with 30 to 100 U/ml. The phenotypes of CD3-AK cells maintained in IL-2 or in IL-4, with or without PMA, were the same: Thy1+ and CD8+. These results were reproduced with purified T cells and purified CD8+ cells, indicating that both the effectors and precursors were CD8+ cells and IL-4 had a selective effect to upregulate the CD8+ cells. Similar results were obtained by using SSP (staurosporine), another PKC inhibitor. At 2 days prior to testing, switching the lymphokine added to 2-week PMA- and IL-2-maintained CD3-AK cells reversed their cytolytic activity: switching from IL-2 to IL-4 restored cytolytic activity, and switching from IL-4 to IL-2 reduced cytolytic activity. The cytolytic activity of these CD3-AK cells correlated with their ability to produce BLT-esterase. In the absence of PMA, CD3-AK cells cultured in either IL-2 or IL-4 were cytolytic and contained high levels of BLT-esterase. In contrast, in the presence of PMA, only the IL-4-maintained CD3-AK cells were cytolytic and produced significant amounts of BLT-esterase. The effect of IL-4 was abrogated by the alpha IL-4 antibody 11B11, which reduced the cytolytic activity of CD3-AK and the ability to produce BLT-esterase. The requirement of IL-2 was less stringent and its major role appeared to be maintaining the cell growth. These findings indicate that IL-4 may participate in the regulation of a PKC-independent pathway for the generation of CD3-AK cells by regulating the production of cytolytic granules.