A method for producing a clone of an immortalised human B memory lymphocyte, comprising the step of transforming human B memory lymphocytes using Epstein Barr Virus (EBV) in the presence of a polyclonal B cell activator. The method is particularly useful in a method for producing a clone of an immortalised human B memory lymphocyte capable of producing a human monoclonal antibody with a desired antigen specificity, comprising the steps of: (i) selecting and isolating a human memory B lymphocyte subpopulation (ii) transforming the subpopulation with Epstein Barr Virus (EBV) in the presence of a polyclonal B cell activator (iii) screening the culture supernatant for antigen specificity and (iv) isolating an immortalised human B memory lymphocyte clone capable of producing a human monoclonal antibody having the desired antigen specificity.
