In vitro recognition of alloantigens: nature of responding and stimulating cells

Increased stimulatory capacity of spleen cells from adult thymectomized mice in mixed lymphocyte reactions

Conflicting results have been reported concerning the effect of adult thymectomy (A-Tx) on the mixed lymphocyte reaction (MLR) response. Our purpose was to test the reverse question, namely the effect of A-Tx on the stimulatory capacity of mouse lymphocytes carrying allelic disparities at the Mls and the H-2 loci. Spleen cells from A-Tx CBA donors were found to be significantly more stimulating than cells from normal donors. That A-Tx could eliminate suppressor T cells involved in MLR regulation or in preventing back stimulation is not likely according to our data. An increment in expression or in accessibility of Mls or H-2 antigenic determinants induced by A-Tx is no more likely, since a smilar increase in lymphocyte proliferation was observed in syngeneic cultures. The most probable explanation remains that A-Tx discloses a strongly stimulatory subpopulation, perhaps acting in part nonspecifically. The hypothesis of an enrichment in B cells versus a loss of T cells is not compatible with our findings, since B-cell-enriched fractions from various origins never attained the stimulating ability disclosed by A-Tx cells. Moreover, the cell involved is theta-positive, although slightly nylon-wool-adherent, and thus shares several properties with immature T cells involved in auto-rosette formation.

Rapid method for purification of human T lymphocytes for further functional studies

We have evaluated a commercially available reagent, T Lympho-kwik, for ability to provide enriched, functional human T cell populations. We have found that this method is more rapid, reliable and efficient than other available methods of T cell isolation and/or macrophage depletion. Although the T Lympho-kwik-treated peripheral blood mononuclear cells (PBMC) are enriched for T cells, devoid of macrophages, and are not activated by the T Lympho-kwik reagent, they can be induced to proliferate, secrete lymphokines and/or develop alloreactive cytolytic T cell activity under appropriate experimental conditions. Hence, T Lympho-kwik treatment of PBMC is a highly effective technique for providing enriched T cells that are free of accessory cells and that can be used for further functional studies.

Xenogenic response of human peripheral blood lymphocytes against murine cells in vitro

Human peripheral blood lymphocytes (HPBL) were sensitized to mitomycin-treated murine spleen cells and mitomycin-treated mastocytoma P-815. A DNA proliferative response occurred to both cell types. The sensitized HPBL lysed chromium-51-labelled mastocytoma P-815 cells in a cell-mediated cytotoxicity assay (CMC). Evidence is presented that this human-murine xenogeneic system involves T cell response with specificity in CMC mainly toward H-2 antigens. DBA/2 splenocytes were superior to mastocytoma cells as sensitizers in the xenogeneic DNA proliferative assay.

Functional analysis of lymphoid cells from mouse bone marrow in vitro

The present results show that mouse bone marrow (BM) cells responded in vitro against phytohaemagglutinin (PHA), concanavalin A (Con A) and lipopolysaccharide (LPS). In addition, BM cell suspensions contained relatively many cells with ADCC (antibody-dependent cell-mediated cytotoxicity) activity. BM cells were fractionated according to various cell surface characteristics. The results of these experiments were compared with previously published reports, showing that pre-T and pre-B cells could be separated on Ig anti-Ig columns (Ig = immunoglobulin). The combined results showed that pre-T cells may fractionate together with cells with the following characteristics: they displayed ADCC activity and had Fc receptors (FcR) and/or membrane Ig. Pre-B cells fractionated with cells with the following characteristics: they responded to LPS but had no ADCC activity. They were not adherent and/or phagocytic and were Ig-, FcR- and C3 receptor (C3R) negative.

Arming of macrophages with lymphocytes from mice immunized with tumor tissue

C57BL/6 macrophages are rendered specifically cytotoxic ("armed") by incubation with spleen cells from C57BL/6 mice sensitized in vivo with allogeneic P-815 mastocytoma cells. Data are presented which suggest that the cytotoxic activity of the macrophages is not due to the adherence of sensitized lymphocytes. The results indicate that it is the T-lymphocyte which is primarily involved in arming. Furthermore it is the cytotoxic and not the proliferating T-cell which is responsible for arming.