Anti Monoclonal Antibody Research Articles

Inhibition of human neuroblastoma development in nude mice by use of monoclonal antibodies

The human neuroblastoma cell line LA-N-1 may form subcutaneous tumors in nude mice. The purpose of this study was to evaluate passive immunotherapy of human neuroblastoma using 390 monoclonal antibody that detects Thy-1 determinant on the cell surface of LA-N-1 neuroblastoma cells. The effect of the 390 antibody alone and combined with complement was tested in nude mice of NIH Swiss background and BALB/c, nu/nu mice challenged with different dosages of LA-N-1 tumor cells. Intraperitoneal administration of anti Thy-1 monoclonal antibody of the IgG2 class has prevented the appearance of subcutaneous LA-N-1 neuroblastoma tumors as evidenced by a very low incidence of tumors in nude mice treated daily, intraperitonealy, with 2 mgr IgG2 of monoclonal antibody 390 and 0.1 ml rabbits complement. In the very few nude mice developing LA-N-1 neuroblastoma tumors under treatment, tumor development required a long latency period compared to control animals. The anti Thy-1 monoclonal antibody had no effect on survival of animals, or tumor size of well established neuroblastoma tumors, compared to control nude mice.

Uptake of neoglycoproteins via membrane lectin(s) of L1210 cells evidenced by quantitative flow cytofluorometry and drug targeting.

The presence and the sugar specificity of membrane lectins on the cell surface of mouse L1210 leukemia cells were demonstrated by using various neoglycoproteins (glycosylated serum albumin) substituted with fluorescein or methotrexate. Neoglycoproteins were prepared by reaction of glycosidophenylisothiocyanates with bovine serum albumin. The binding of neoglycoproteins to L1210 cells depends on the nature of the carried sugar and on the number of bound sugar residues per neoglycoprotein molecule. The best results were obtained with fucosylated serum albumin containing 25 +/- 5 residues of fucose. The amount of cell-associated fluorescein-labeled neoglycoproteins was several fold higher at 37 degrees C than at 4 degrees C suggesting a specific endocytotic process. The membrane lectin-mediated endocytosis was further demonstrated by showing that the cell-associated fluorescence upon cell incubation in the presence of fluorescein-labeled neoglycoproteins at 37 degrees C increased several fold after addition of monensin, a proton/sodium ionophore known to raise the pH of endosomes and lysosomes. The analysis of fluorescein-labeled neoglycoproteins association to the L1210 cells were achieved by quantitative flow cytofluorometry after standardization with calibrated polystyrene sulfonate beads carrying various amounts of 1-(fluoresceinylthioureido)-4,8-diazalicosane. In addition, the cytotoxicity of neoglycoprotein-bound methotrexate was shown to be related to the presence and to the nature of the carried sugar: fucosylated serum albumin was shown to be the most efficient neoglycoprotein carrier, and to have a cytotoxicity close to that of anti L1210 cell IgM monoclonal antibody carrying methotrexate.

The products of transferred H-2 genes express determinants that restrict hapten-specific cytotoxic T cells.

Cell lines into which cloned H-2 genes had been introduced (i.e., transformants) were used to correlate the genes and their products that are capable of functioning as H-2 restriction elements for hapten-self-(AED and TNP) specific cytotoxic T cells (CTL). These transformants provided a unique system in which major histocompatibility restricted (MHC) T cell recognition could be examined by using cells that express only H-2Ld or only H-2Dd gene products. BALB/c (H-2d) anti AED-self CTL lysed both the H-2Ld and Dd transformants, but not parental, i.e., untransformed, cells. The AED-self lysis of the Ld and Dd transformants was shown to be specifically inhibited by anti-H-2Ld and anti H-2Dd monoclonal antibody, respectively. In contrast to these results, BALB/c anti TNP-self CTL were found to lyse readily the Dd but not Ld transformed lines, supporting reports indicating that H-2Ld-restricted TNP-self CTL could not be detected. The results of this study thus demonstrate that the cell surface products encoded by these transferred MHC class I genes contain self determinants recognized by CTL.

Production and Regulation of Interleukin-2 in Human Lymphoblastic Leukemias Studied With T-Cell Monoclonal Antibodies

Human leukemias are illnesses of hemopoietic stem cells that go through processes of self-replication and partial differentiation under the control of as yet largely unknown growth and differentiation factors. IL-2 is a powerful factor controlling proliferation of normal T cells. We report that acute lymphoblastic leukemias of T and non-B, non-T phenotypes produce a growth factor after mitogen stimulation. This factor is able to support the proliferation of human and murine IL-2-dependent cytotoxic cells, has a mol wt of 26,000 daltons by gel filtration, an isoelectric point of 6.6, and its biologic activity is inhibited by an anti IL-2 monoclonal antibody. This factor is, therefore, by all parameters studied very similar to IL-2 produced by normal lymphocytes. A recently developed monoclonal antibody, Pan T2, binds to normal T cells, renders T cells responsive to IL-2, and induces the release of IL-2, which in turn provides the second signal for T-cell proliferation. Mononuclear cells from acute lymphoblastic leukemia do not respond to the addition of this monoclonal antibody unless cocultured with irradiated Daudi cells. Since normal T cells do not require Daudi to produce IL-2 and since Daudi cells do not produce IL-2 under any conditions, we conclude that the cell responsible for IL-2 production in acute lymphatic leukemia is a leukemic T cell with an altered mechanism of IL-2 production at the level of the Pan T2 binding site.

Production and regulation of interleukin-2 in human lymphoblastic leukemias studied with T-cell monoclonal antibodies

Human leukemias are illnesses of hemopoietic stem cells that go through processes of self-replication and partial differentiation under the control of as yet largely unknown growth and differentiation factors. IL-2 is a powerful factor controlling proliferation of normal T cells. We report that acute lymphoblastic leukemias of T and non-B, non-T phenotypes produce a growth factor after mitogen stimulation. This factor is able to support the proliferation of human and murine IL-2- dependent cytotoxic cells, has a mol wt of 26,000 daltons by gel filtration, an isoelectric point of 6.6, and its biologic activity is inhibited by an anti IL-2 monoclonal antibody. This factor is, therefore, by all parameters studied very similar to IL-2 produced by normal lymphocytes. A recently developed monoclonal antibody, Pan T2, binds to normal T cells, renders T cells responsive to IL-2, and induces the release of IL-2, which in turn provides the second signal for T-cell proliferation. Mononuclear cells from acute lymphoblastic leukemia do not respond to the addition of this monoclonal antibody unless cocultured with irradiated Daudi cells. Since normal T cells do not require Daudi to produce IL-2 and since Daudi cells do not produce IL-2 under any conditions, we conclude that the cell responsible for IL- 2 production in acute lymphatic leukemia is a leukemic T cell with an altered mechanism of IL-2 production at the level of the Pan T2 binding site.

Monoclonal antibodies distinguish between wild and vaccine strains of yellow fever virus by neutralization, hemagglutination inhibition, and immune precipitation of the virus envelope protein

Nineteen monoclonal antibodies were produced to the 17D strain of yellow fever virus (17D YF). Virus-specific structural and nonstructural proteins were identified for 17D YF and for the parent wild Asibi YF by radioimmunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Fourteen of the monoclonal antibodies were directed against the envelope glycoprotein, E, and five against the nonstructural protein gp 48. The E protein of 17D YF was resolved as a double complex whereas the E protein of Asibi YF appeared as a single band of slightly lower molecular weight. The only IgM anti-E antibody obtained precipitated and neutralized 17D YF specifically with no activity against Asibi YF. This antibody also distinguished clearly by neutralization (N) between the 17D-204 derived vaccine strain to which the animal had been immunized and 17D YF strains of different origin. All 13 IgG anti-E monoclonal antibodies had hemagglutination-inhibition (HI) activity to 17D YF and all but one neutralized Asibi YF; however, only 3 of the 13 neutralized 17D YF. Four anti-E antibodies cross-reacted with other flaviviruses by HI or HI and N. Three of the five anti-gp 48 antibodies had complement-fixation (CF) titers against 17D YF and Asibi YF but none had N or HI activity.

Expression of Lyt-1 antigen on certain murine B cell lymphomas.

Although the Lyt-1 antigen has previously been considered a T cell-specific marker, recent evidence suggests that a population of Thy-1-, Lyt-1+ cells exists in normal lymphoid tissues. In this study, we have observed that the WEHI-55, WEHI-259, and CH5 B cell lymphomas express high levels of the Lyt-1 antigen, as detected by monoclonal antibodies using the fluorescence activated cell sorter. Three other B cell lymphomas of the 11 examined also gave weak but detectable reactions with the anti Lyt-1 monoclonal antibody. Except for the expression of the Lyt-1 antigen, these lymphomas are typical of cells in the B cell lineage with respect to surface phenotype. The Lyt-1 glycoprotein immunoprecipitated from metabolically labeled WEHI-55 cells is similar in structure to the Lyt-1 glycoprotein on thymocytes. These findings are similar to recent reports that B-type human lymphocytic leukemia cells express the putative human homologue of Lyt-1, the Leu-1 antigen.