EBV transformation and microfusion as the potential source of human monoclonal antisperm antibodies

Monoclonal antibodies against antigens expressed by human sperm

The production and characterization of 21 mouse monoclonal antibodies (TüS1-TüS21) with specificity predominantly for human spermatozoa antigens is described. Reactivity of cells from human ejaculates, peripheral blood and several organs was determined using the alkaline phosphatase-anti-alkaline phosphatase (APAAP)-technique as well as the indirect immunofluorescence test. 15 of the monoclonal antibodies reacted with various regions of human sperm and often also with their precursor cells in the testis. Cross-reactivity with animal spermatozoa was frequently observed.

Preparation of human-mouse heterohybridomas against an immunising antigen

The production of murine monoclonal antibodies against specific antigens by hybridomas is a well utilised technique. The production of hybridomas secreting specific human antibodies would have many advantages in therapeutic applications of monoclonal antibodies. The immortalised human lymphocytes themselves would also provide valuable tools in research on lymphocyte development. Preparation of human-human hybridomas has been limited by a lack of suitable fusion partners. This protocol paper describes the production of human-mouse heterohybridomas by two independent laboratories. The purpose of this protocol is to provide a basis for the development of heterohybridoma technology in laboratories with limited hybridoma experience.

Characterization of anti-sperm antibodies and their coding cDNA sequences by Epstein-Barr virus transformed B cell lines from lymphocytes of infertile women possessing anti-sperm antibodies

Epstein-Barr virus (EBV)-transformed B cell lines that produce human antisperm antibodies were established using peripheral blood lymphocytes (PBLs) from infertile women with sperm immobilizing antibodies in their sera. We obtained three stable cell populations (designated B1, B2, D5) of transformed PBLs originating from three different patients. They produced IgM sperm-reacting antibodies directed against the tail of live, methanol-fixed and NaIO4-treated human spermatozoa. The established antisperm antibodies recognized noncarbohydrate sperm membrane antigens with different specificity and distribution in the male reproductive system. Antisperm antibody-B2 corresponding antigen appears to be specific for the male reproductive system. This antigen is excreted from the epithelial cells of the ductus epididymidis and bound to the spermatozoa in the lumen of the ductus. Antisperm antibodies B1 and D5 corresponding antigens were expressed on the spermatozoa in the seminiferous tubules and were common to the secretions of the ductus epididymidis, prostate and some other somatic organs. The cDNA of the immunoglobulin heavy chain genes were analyzed by reverse transcription polymerase chain reaction (RT-PCR) using RNA extracted from these clones. The immunoglobulin heavy chain cDNA sequences of these antisperm antibodies showed extremely high homology to previously reported immunoglobulin germline DNA sequences, implying that these antisperm antibodies might be natural autoantibodies rather than antibodies stimulated by external antigen.

In vitro sensitization for human monoclonal antibody production

We have found that cell adhesion prior to in vitro antigenic stimulation enriched the B-cell population and diminished the CD8 lymphocyte subset. These changes in lymphocyte proportions were favourable for increasing the percentage of antibody-producing cells after culturing in vitro followed by Epstein-Barr virus (EBV) infection. The immunodepletion of leukocytes by methyl esters did not yield satisfying results under analogous culture conditions. In vitro primary antigenic stimulations with the addition of IL-2 (25 U/ml medium) and low amounts of interferon-gamma provided better recruitment of antibody-producing cells and higher binding activity of antibodies to sperm than secondary antigenic stimulation. IL-6 did not positively influence the EBV-transformed cell lines.