A method for producing a clone of an immortalized 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 immortalized 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 Ban virus (EBV) in the presence of a polyclonal B cell activator； (iii) screening the culture supernatant for antigen specificity； and (iv) isolating an immortalized human B memory lymphocyte clone capable of producing a human monoclonal antibody having the desired antigen specificity.
