L-asparaginase and in vitro lymphocyte blastogenesis. Cell membrane alteration as possible mechanism of inhibitory effect

Lymphocytes which were incubated with Erwinia carotovaraL-asparaginase for only 1 hour were found to be markedly non-responsive to soluble antigens and moderately non-responsive to allogeneic cells or phytohaemagglutinin. When lymphocytes were exposed to antigen first, the inhibitory effect of L-asparaginase was markedly diminished, whereas exposure of lymphocytes to the enzyme prior to contact with antigen resulted in almost complete inhibition of blastogenesis. These observations suggest that L-asparaginase acts on the cell membrane causing impairment of antigen or mitogen binding, and that this is responsible for its inhibitory effect.

A unique 'leukaemic' T lymphoid cell line: absence of stimulating effect in mixed lymphocyte reaction. Lack of MLR-S in leukaemic T lymphoid cells

`One-way' mixed lymphocyte reactions between fresh, normal, peripheral blood lymphocytes of human or baboon and irradiated or mitomycin C-treated cultured `leukaemic' T lymphoid cells (MOLT-4) were absent in all of forty-six experiments. In contrast, the lymphocytes from the same donors were significantly stimulated by cultured normal B lymphoid cells (B411-4) or Burkitt's lymphoma B lymphoid cells (B35M) in each instance. Neuraminidase-treated MOLT-4 cells also exerted no stimulating effect on allogeneic lymphocytes. Lack of stimulating effect of MOLT-4 cells suggests the possibility that the MLR-S of leukaemic cells may have been lost or masked during the process of leukaemogenesis or during in vitro cultivation.

'Immune' RNA-mediated transfer of delayed skin reactivity in patients with Hodgkin's disease

Intradermal injection of `immune' RNA extracted from the peripheral blood lymphocytes of sensitive donors unequivocally transferred PPD, Varidase and monilia skin test responses in nine of ten patients with Hodgkin's disease. The transfer of skin reactivity was seen by intradermal injection of `immune' RNA, a few cm from the site of skin test or on the opposite forearm, suggesting that the `immune' RNA is systematically active.

Synergism of stimulating capacity of pooled lymphocytes in the mixed lymphocyte reaction

One-way mixed lymphocyte reactions in cultures of responding cells from a single subject and a pool of stimulating cells from two or more donors exhibited a synergistic response. Increased activity of the responding cells showed a positive correlation with the pool size. Treatment of the responding cells, stimulating cells or both with neuraminidase significantly increased the response.

Enhancement of in vitro lymphocyte response by neuraminidase

In vitro blastogenic response of sensitized human lymphocytes to specific antigens was significantly enhanced by Vibrio cholerae neuraminidase treatment. No such enhancement was noted when the unsensitized lymphocytes were treated with this enzyme. An enhancement effect of neuraminidase on the lymphocyte response to concanavalin A or pokeweed mitogen (weak mitogens) was also noted; the enzyme had no effect on phytohaemagglutinin (strong mitogen)-induced blasto-genesis. The increased reactivity of lymphocytes is probably related to changed physical and functional properties of the cells after treatment with neuraminidase.

'Antigenic' disparity between leukaemic lymphoblasts and normal lymphocytes in identical twins

Circulating lymphocytes of a normal boy were unequivocally stimulated by irradiated leukaemic lymphoblasts from his identical twin with acute lymphoblastic leukaemia. This reaction indicates that there is an `antigenic' disparity between these two types of cells. It is possible that leukaemic cells may acquire new surface antigens or that existing surface antigens of lymphoid cells may be modified during the process of leukaemogenesis.

Blastogenic response of normal lymphocytes to cultured lymphoid cells and non-lymphoid neoplastic cells

Irradiated cultured lymphoid cells (normal and leukaemic) unequivocally stimulated the peripheral lymphocytes from twelve normal individuals. However, irradiated cultured non-lymphoid neoplastic cells (KB cells, melanoma cells and osteogenic sarcoma cells) exerted little or no stimulating effect on lymphocytes of the same donors. These findings indicate that something more than a simple HL-A incompatability is involved in this mixed cell interaction.