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.

Simplified whole blood method for evaluating in vitro lymphocyte reactivity of laboratory animals

A whole blood culture technique has been employed to quantitatively evaluate lymphocyte reactivity of small laboratory animals including mice, rats, guinea-pigs and rabbits. This simplified method has been used to study the blastogenic response to phytohaemagglutinin, concanavalin A, pokeweed mitogen and staphy-lococcal filtrate. Tuberculin-induced lymphocyte transformation responses have been studied in serial experiments using sensitized animals. The results of this preliminary study demonstrate that the whole blood method has numerous advantages over the conventional techniques employing leucocyte concentrates. In almost all instances the degree of lymphocyte reactivity as measured by ³H-thymidine incorporation closely approximated or exceeded previously reported results using the standard culture method.