Band 4 protein, isolated from bovine parotid saliva, was used to immunise BALB/c mice. Monoclonal antibodies specific for this protein were made by fusing spleen cells from immunised BALB/c mice with the mouse myeloma cell lines SP2/0 or MPC/11. About 10 of cultures which contained hybridomas secreted antibodies to band 4 protein, and of these, 2 high producers were selected and cloned to give stable cell lines AB4/1 and AB4/2. These have been cultured continuously for more than 6 months without any loss of antibody secretion. Ascitic tumours producing high titres of antibodies to band 4 could be induced in pristane-primed mice within 2 weeks following injection of 104hybridoma cells from these lines. Both lines produce IgG antibodies. AB4/1 antibody would bind to protein A-sepharose and could be eluted at pH 6.5, indicating that it is probably of IgG1subclass. AB4/2 antibody did not bind to protein A. Both monoclonal antibodies react only with the band 4 of the salivary proteins, and each antibody appears to recognise a different antigenic determinant on the band 4 molecule, or to have a different affinity for the same determinant.
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