Jolanta E. Kunicka

Immunoglobulin synthesis and secretion by leukemic B cells from patients with chronic lymphocytic leukemia.

We investigated the ability of purified E-rosette negative largely leukemic B cells from 15 patients with B-cell chronic lymphocytic leukemia (CLL) to synthesize and secrete IgM, IgA and IgG spontaneously or in the presence of purified autologous or allogeneic T4 cells from normal donors, in PWM-induced differentiation system. We observed moderate but significant IgM synthesis and secretion (19.7 +/- 8.9 micrograms/dl, n = 5) by leukemic B cells alone in 5 of 15 patients examined. These IgM concentrations were significantly higher (p less than 0.005) than those produced by purified E-rosette negative cells from normal donors (4.3 +/- 4.5 micrograms/dl; n = 6) in the absence of T cells. Purified E-rosette negative leukemic B cells alone from patients with CLL did not produce IgA or IgG. Addition of purified autologous or allogeneic T4 cells from normal donors resulted in significant increase of IgM production by leukemic B cells from certain patients or initiated IgM secretion in others. However, these IgM levels (73.9 +/- 56.6 micrograms/dl) were significantly lower (p less than 0.003) to those produced by mixtures of T4 cells and B cells form normal donors (211.6 +/- 58.0 micrograms/dl, n = 6). Addition of purified autologous or allogeneic T4 cells from normal donors to purified largely leukemic B cells from patients with CLL resulted in production of very small amounts of IgA in 4 of 15 patients (10.6 +/- 6.3 micrograms/dl vs 154.7 +/- 35.8 micrograms/dl produced by T4 and B cells from normal donors; n = 6), but did not support IgG synthesis and secretion. Purified T4 cells from certain patients with CLL exhibit defective helper function to immunoglobulin production by E-rosette negative cells from normal donors.

Caffeine increases sensitivity of DNA to denaturation in chromatin of L1210 cells

Abstract.

Induction of suppressor cells to T- and B-cell proliferative responses and immunoglobulin production by monoclonal antibodies recognizing the CD3 T-cell differentiation antigen☆

Monoclonal antibodies (mAbs) recognizing the CD3 T-cell differentiation antigen induced the generation of suppressor cells. These cells inhibited (1) proliferative responses of human peripheral blood mononuclear cells (PBMC) to PHA and allogeneic cells in mixed leukocyte culture; (2) proliferative responses of purified E-rosette-negative cells to Staphylococcus aureus Cowans I; and (3) de novo immunoglobulin synthesis and secretion in the pokeweed mitogen (PWM)-induced differentiation system. Monoclonal antibodies recognizing other T-cell differentiation antigens (anti-Leu 2a, anti-Leu 3a, and anti-Leu 5) did not induce the generation of suppressor cells, even at very high antibody concentrations. Statistically significant differences were not observed in the ability of the OKT3 and anti-Leu 4 mAbs to induce suppressor cells. Monocytes were not required for the generation of anti-CD3-induced suppressor cells. F(ab)2 fragments of the OKT3 mAbs were equally effective when compared with intact antibody molecules in inducing suppressor cells, although they did not induce proliferative responses. Proliferation was not required for the induction of suppressor cells. Irradiation (2500 rad) of PBMC before incubation with the anti-CD3 mAb did not affect the generation of suppressor cells. Furthermore, anti-CD3-induced suppressor cells were radioresistant. Addition of recombinant IL-2 to the cultures of responding cells and suppressor cells did not reverse the suppression. In vitro treatment of anti-CD3-induced suppressor cells with either the OKT4 mAb plus complement or the OKT8 mAb plus complement partially decreased the suppression of proliferative responses of PBMC to PHA or allogeneic cells in mixed lymphocytes culture. However, treatment with both OKT4 and OKT8 mAbs plus complement or the OKT11 mAb plus complement completely abolished the suppression. These results suggest that the suppressor cells are of the T11+T4+T8- and T11+T4-T8+ phenotypes. In other experiments, T4+T8- and T8+T4- cells were isolated from PBMC treated for 48 hr with anti-CD3 mAbs. Both these two populations significantly inhibited proliferative responses of autologous PBMC to PHA and de novo immunoglobulin synthesis and secretion by mixtures of purified T4 and B cells from normal donors, in the PWM-induced differentiation system. These results demonstrate that anti-CD3-induced suppressor cells are of the T4 or T8 phenotype. Treatment of purified T4+T8- and T8+T4- cells with anti-CD3 mAbs resulted in the generation of suppressor cells, suggesting that the precursors of the anti-CD3-induced suppressor cells can belong to either of these two populations.(ABSTRACT TRUNCATED AT 400 WORDS)

Hybridoma-derived human suppressor factors: Inhibition of growth of tumor cell lines and effect on cytotoxic cells

With the objective of developing human T-T cell hybrids producing B-cell growth factor, we fused concanavalin A-activated T lymphocytes with cells of the Jurkat T cell line. The hybrids were selected on the basis of their ability to form colonies in soft agar, whereas the parent Jurkat T cell line did not. T-T cell hybrids were HLA-typed, screened by functional tests, and recloned by limiting dilution. In addition to obtaining B-cell growth factor-producing hybrids, we also obtained certain other T-T cell hybrids (as determined by HLA-typing) producing suppressor factors inhibiting proliferative responses and antibody production by human lymphocytes. Subsequently, a suppressor factor with similar inhibitory properties was identified in supernatants of the Jurkat T cell line. However, the Jurkat factor exhibited different biochemical and functional properties than the hybridoma-derived suppressor factors. Using two-parameter cell cycle analysis and the metachromatic fluorochrome acridine orange, we found that the hybridoma-derived 160 and 169 suppressor factors arrested phytohemagglutinin-induced proliferative of peripheral blood mononuclear cells in the G0/G1 phase of the cell cycle, whereas the Jurkat suppressor factor arrested proliferation in the S phase. Incubation of peripheral blood mononuclear cells with the 160, 169, or Jurkat suppressor factors for 24 hr at 37 degrees C, followed by washing, did not alter their cell cycle progression (or RNA content) in response to stimulation with phytohemagglutinin. The hybridoma-derived 160 and 169 suppressor factors and the Jurkat factor inhibited the growth but not the viability of cells from the following human tumor cell lines: A673 sarcoma cell line, SK-LC-6 and SK-LC-14 lung cell lines, SB, Raji, and Daudi lymphoblastoid cell lines, and FARR malignant melanoma cell line. In contrast, it did not affect the growth of murine L1210 cells and FS-4 normal human diploid fibroblasts. The hybridoma-derived 160 suppressor factor was selected to investigate its effect on cell-mediated cytotoxicity. The 160 suppressor factor did not inhibit natural killer cytotoxicity or its augmentation by interferon alpha or interleukin 2 or the generation of lymphokine-activated killer cells. However, this factor partially inhibited the generation of specific T cell-mediated cytotoxicity.

Monoclonal Antibodies Recognizing the T3/Leu 4 T Cell Differentiation Antigen Induce Suppressor Cells

The OKT3 and anti-Leu 4 monoclonal antibodies define a T cell surface differentiation antigen selectively expressed on functionally mature T cells (1,2). This antigen exhibits a complex biochemical structure consisting of at least three polypeptides with molecular weight in the range of 19–26 Kd (3–5). Monoclonal antibodies recognizing the T3/Leu 4 antigen exhibit profound effects on various T cell functions, including: (a) inhibition of proliferative responses of human peripheral blood lymphocytes to mitogens and allogeneic cells in mixed lymphocyte culture (6,7); (b) inhibition of T cell helper function to B cell responses (6); (c) inhibition of specific T cell-mediated cytotoxicity at the effector phase (7,8) and at a post-adhesion stage of the cytolytic process (9–12). It has been suggested that the T3 antigen may be associated with triggering of T cell functions and signal transfer or transduction (12).