AN ORGAN FRAGMENT CULTURE MODEL TO STUDY LYMPHOCYTE-ACTIVATION IN HUMAN LYMPHOID-TISSUE

We have established and evaluated an organ fragment culture model for the study of human lymphocyte activation and differentiation. Small fr agments of tonsillar tissue were cultured on Gelfoam for periods of up to 7 days. Monoclonal antibody in the medium was able to diffuse into the tissue, as demonstrated by subsequent detection of antibody-coate d cells. Phytohaemagglutinin added to the culture medium caused activa tion of T and B cells, as indicated by changes in expression of a numb er of markers. Antibody against human IgM (added as a F(ab')2 fragment ) together with IL-4 caused B cell activation, detectable by an increa sed expression of CD23 and other markers. Cell viability fell graduall y in culture, but useful data could nevertheless be obtained from cult ure periods up to 7 days. The organ fragment culture provides a model for the study of T and B cell activation which maintains, at least in part, the intercellular interactions and the native microenvironment o f lymphoid tissue.