Production of monoclonal human antibody to HLA-DR5 (DRw11) by mouse/human heterohybridomas

From antibodies to sperm to antibodies in transplantation

OBJECTIVES

a) To assess the use of "panning" procedures for the detection of antibodies to sperm. b) To develop and use human monoclonal antibodies for the analysis of human transplantation antigens.

METHODS

"Panning" assays were developed. The procedures and their use in the analysis of mouse monoclonal antibodies to human sperm are described. B-lymphocytes from individuals sensitized by pregnancy, graft rejection, or blood transfusion were immortalized with Epstein-Barr virus (EBV). Selected sublines producing antibodies to human leukocyte series A (HLA) antigens were fused with mouse myeloma cells and selected clones of hybrid cells secreting monoclonal antibodies were selected.

RESULTS

The results of panning assays correlated with those of agglutination assays, but not immunofluorescence or enzyme-linked immunosorbent assays (ELISA). Monospecific and cross-reactive human monoclonal antibodies to HLA antigens were produced.

CONCLUSIONS

Panning assays can be used for the detection of antibodies to sperm and can be useful where target sperm are of poor motility. The assays may be more sensitive for antibodies to superficial antigens. Human monoclonal antibodies may be used for investigating the identity of, and responses to, transplantation antigens.

Enhanced efficiency of cell hybridization by neuraminidase treatment

Cell hybridization techniques have already been utilized, but the outcome is usually not very stable. In order to achieve high stability we tried to achieve closer intercellular contact. Neuraminidase treatment was used to remove sialic acid from the cell membrane, since sialic acid usually prevents close contact between B cells and myeloma cells. After neuraminidase treatment, not only mouse-mouse hybridization but also human-mouse hybridization produced significantly more clones. Our results indicate that neuraminidase treatment is a useful method for generating hybridomas efficiently.

Characterization of three human monoclonal antibodies specific for polymorphic class I and class II HLA antigens

Three human monoclonal antibodies were derived from a single polytransfused patient awaiting renal transplantation. In microcitotoxicity assays, the patient's serum displayed strong positive reactions against greater than 90% of a panel of cells representing the known HLA specificities. The donor's peripheral blood lymphocytes were infected with Epstein-Barr virus, cloned, and supernatants of the virus transformed cultures were screened for the presence of IgG antilymphocyte reactivity utilizing an enzyme-linked immunosorbent assay method. Positive cultures were recloned and fused with the human-mouse heteromyeloma SHM. Supernatants from three clones were selected for alloreactivity and characterized by indirect immunofluorescent staining and fluoroactivated cell sorter analysis on homozygous typing cells, including those from the Tenth International Histocompatibility Workshop core panel and on cell lines derived from selected families. Data obtained demonstrate that two human monoclonal antibodies have DQw1 specificity, one of them being reactive against several DQw7-positive cell lines, while one monoclonal antibody is specific for the A2 + A28 class I MHC antigens. Anti-DQw1 antibodies were of different light-chain subtypes.

Production of a cytotoxic human monoclonal antibody with specificity for HLA-DR4 and -DRw10 by cells derived from a highly sensitized kidney recipient

A human monoclonal antibody which reacts preferentially with HLA-DR4 and -DRw10 B-cell targets has been produced. A human B-cell line, secreting antibody which reacted preferentially with DR4 and DR1 targets, was derived from a highly sensitized kidney recipient who had rejected two grafts. This line was fused with the mouse myeloma P3X63Ag8.653 and a selected hybridoma cloned. The clones secrete IgM(lambda), which reacts strongly with HLA-DR4 and -DRw10 and more weakly with -DRw14 and a proportion of -DR1 B cells in cytotoxicity assays. Using B-cell lines as targets in cytotoxicity and enzyme-linked immunosorbent assays, the antibody gives a broader pattern of reaction, reacting with HLA-DR1, -DR4, -DR9, -DRw10, -DRw14, and some -DR2 targets. The antibody (NI) is currently in use as a reagent for tissue typing.

MicroELISA assays of anti-HLA activity and isotype of human monoclonal antibodies

Both monoclonal human antibodies to HLA-DR antigens and supernatants from oligoclonal B-cell lines can be conveniently screened for activity by microELISA assays which use 1/10 of the volume of reagents used in conventional ELISA assays. Target cells are fixed to the bases of wells in Terasaki plates, 5 microliters volumes of supernatants incubated in these wells, and target bound antibody detected by peroxidase-conjugated anti-immunoglobulin followed by the substrate ABTS(2,2'-azino-di-(3-ethylbenzthiazoline sulphonate). The plates are read on a micro EIA reader. Supernatants can also be assayed for immunoglobulin content and isotype in Terasaki plates by coating the wells with isotype-specific anti-immunoglobulin, adding test supernatant and developing with appropriate peroxidase-conjugated anti-immunoglobulin sera and ABTS. When assaying for immunoglobulin content, the plates can be read either with a reader or by eye. Advantages and modifications of these procedures are discussed. There are no apparent practically important disadvantages to these procedures as compared with more conventional ELISA assays.