An autocrine growth factor constitutively produced by a human lymphoblastoid B-cell line is serologically related to lymphotoxin (TNF-beta).

Conditioned medium of a human lymphoblastoid B-cell line RPMI-6410t contains a factor sufficient for maintainance and growth of these cells. At the same time RPMI-6410t cells secrete a soluble factor cytotoxic towards mouse L929 cells. Production of these activities by RPMI-6410t cell line and its subclones is significantly enhanced after activation with phorbol mirystate acetate (PMA).

[Reversible suppression and activation of immunoglobulin genes in differentiated IgG+ sublines of human RPMI-6410t B-cells].

Differentiated human B-cells of the IgG+ sublines obtained as a result of switching from IgM to IgG synthesis in the 6410t line and its IgM+ lines gradually reduce the level of IgM secretion after the inductor removal. IgG synthesis can be partially or fully recovered by treating the IgG+ sublines with a polyclonal activator of B-lymphocytes, lipopolysaccharide W from Gram negative bacteria. In the conditions of certain regulatory effects, differentiated IgG+ cells are capable to pass reversibly in the state of functional rest and synthesis initiation.

[Instability of immunoglobulin expression during differentiation induction in the human lymphoblastoid cell line RPMI-6410t].

The induction of immunoglobulin heavy chain classes switch from IgM to IgG was demonstrated in vitro in cells of RPMI-6410t line. The IgG+-sublines, formed as a result of the switch are characterized by instability of IgG synthesis. After removal of the inductor from the growth environment, IgG+ cells gradually reduce the level of secreted IgG.

[The biological action spectrum of the secretory products of the human B-cell lymphoblastoid line RPMI-641Ot].

Secretory products of the lymphoblastoid line of human B-cells RPMI-6410t have a wide spectrum of biological activity. These products exert a growth-stimulating effect on B-cells of the 6410t strain obtained from the peripheral blood of a patient with acute myeloblastic leukemia and cytotoxic and cytostatic effects, respectively, on B-cells of the Raji and P3HR-I.G5 lines obtained from patients with Burkitt's lymphoma.

[Switch in the synthesis from IgM to IgG in the human lymphoblastoid cell line RPMI-6410t as affected by human sera].

The switch from IgM to IgG in lymphoblastoid cell line RPMI-6410t was induced by human sera. The factor inducing the switch was found in the human placental serum and in the serum of peripheral blood of healthy donors. The switch investigated is induced both in the initial line 6410t and in some IgM+ sublines derived from it.