Phenotypic, morphologic changes and Ig secretion induced on B-NHL cells in vitro by interferon alpha and all-trans-retinoic acid: possible progression toward a more differentiated state

Twenty-five B-cell-nonHodgkin's lymphomas (B-NHL): 6 lymphocytic, 2 centrocytic, 13 follicular, centrocytic/centroblastic, 2 lymphoplasmocytoid and 2 centroblastic were tested for their ability to acquire features of mature plasma cells under the effect of interferon alpha (final concentration, 600 UI/ml), all-trans-retinoic-acid (ATRA) (final concentration, 10 -6 mol/l) and the association of both. B-NHL cells were negatively purified (>99%) by an immunomagnetic method, cultured for 7 d with or without interferon and ATRA, then stained with anti-CD19, CD20, surface Ig, DR, CD38 and with anti-CD138 (syndecan-1) antibody-recognizing plasma cells. Ig production was estimated in culture supernatants by an ELISA method and changes in cell morphology were investigated on May-Grunwald. -Giemsa-stained cytospin preparations. In all cases interferon and ATRA, alone or in association, were able to induce changes in the immunophenotypic profile, associated or not with morphologic changes and induction of Ig secretion. All changes were greatly variable from one to the other B-NHL sample and no relationship could be found between a particular pattern of change and the histological subtype. Interferon alpha was more potent than ATRA in inducing changes. In favour of a differentiation process, we observed a concomitant decrease of DR expression and increase of CD38 expression in 8 cases with interferon alpha, and in 4 cases with ATRA. Although interferon- or ATRA-treated cells did not display cytologic, functional features and changes of the immunophenotypic profile fully compatible with those of terminally differentiated cells, these results suggest a possible transition toward more differentiated elements, especially with interferon alpha.