Use of xenograft tissue for the initial screening of human monoclonal antibodies by immunohistological technique.

An indirect avidin-biotin-horseradish peroxidase complex (ABC) method was employed to detect binding activity of human monoclonal antibodies at their early state of production to tissue antigens in either fresh-frozen or formalin-fixed and paraffin-embedded tissue sections. The tissues were obtained from xenograft of human tissues that were grown in immune suppressed BALB/c mice. The reaction was visualized by the use of aminoethylcarbazole (AEC) as chromogen. The procedure described here was as sensitive and, most importantly eliminated an inherent problem associated with the use of human tissue section namely the difficulty in distinguishing binding of the primary human monoclonal antibody from endogenous human immunoglobulins in tissue section.