Inhibition of autologous mixed lymphocyte reaction by aggregated IgG molecules

Autologous mixed lymphocyte-tumor reaction and autologous mixed lymphocyte reaction. I. Proliferation of two distinct T-cell subsets

In patients with carcinomatous pleural effusions blood T lymphocytes proliferated in vitro in response to autologous, freshly isolated effusion tumor cells in the autologous mixed lymphocyte-tumor culture (AMLTC) and to autologous blood non-T cells in the autologous mixed lymphocyte culture (AMLC). Treatment of the stimulator cells with the anti-HLA-DR monoclonal antibody (MAb) abrogated the stimulatory capacity in AMLC, but not in AMLTC. A subset of T cells that formed rosettes with autologous erythrocytes showed proliferative response to autologous non-malignant cells, whereas this subset did not respond to autologous tumor cells. Non-adherent lymphocytes were fractionated by centrifugation on discontinuous Percoll density gradients. Medium-sized T lymphocytes were excellent responders in AMLC, but were weak responders in AMLTC. Small T lymphocytes proliferated preferentially in AMLTC, but responded poorly in AMLC. Large granular lymphocytes (LGL) did not proliferate in mixed cultures of either type. Instead, LGL suppressed the T-cell proliferation in AMLTC. The same suppressor LGL, however, had no inhibitory effect on AMLC. Elimination of the CD4 subset reduced or abolished proliferative response in AMLC in all cases, whereas it was ineffective in diminishing the reaction in 6 of 8 AMLTC. In contrast, removal of the CD8 subset decreased or eliminated T-cell proliferation in 4 of 8 AMLTC, but in none of the AMLC. These results indicate that the autoreactive T lymphocytes detectable in response to tumor cells and non-malignant non-T cells differ in several characteristics. Thus, the reaction in the AMLTC is not due to contaminating non-malignant cells in the stimulator population and may be a tumor-induced proliferative response.

Inhibitory effect of an antibody against alpha 1-acid glycoprotein (alpha 1-AGP) on autologous mixed lymphocyte reaction and anti-T3 T-lymphocyte activation

The action of an anti-alpha 1-AGP antibody on AMLR, anti-T3 and PHA T-lymphocyte proliferative response was evaluated. We observed a strong dose-dependent inhibition on T-lymphocyte proliferative responsiveness to autologous non-T cells and to anti-T3 stimulus, whereas PHA activation was unaffected. A lower degree of inhibition of the proliferative response was also observed on pretreating both T and non-T cells with the antibody; the addition of anti-alpha 1-AGP in the culture containing cells pretreated with the antibody showed a further inhibition of thymidine incorporation. The data suggest a direct influence of the antibody on membrane alpha 1-AGP and support a positive role of this glycoprotein (distinct from Ia and T3 antigens) on both anti-T3 and autologous non-T cell T-lymphocyte responsiveness, thus indicating the involvement of alpha 1-AGP in the T3-Ti antigen-specific pathway of T-cell activation.

Impaired killer cell generation in the autologous mixed leukocyte reaction by rheumatoid arthritis lymphocytes

Natural killer-like cells are generated along with interleukin-2 (IL-2) in the autologous mixed leukocyte reaction (AMLR). Patients with active rheumatoid arthritis (RA), but not those whose disease is in remission, are poor producers of AMLR killer cells. This defect cannot be explained by age, medications, or serum factors. The impaired generation of natural killer-like cells was not influenced by gamma-interferon but could be partially restored by addition of indomethacin to the AMLR culture, or by culturing RA T cells with exogenous IL-2. However, the response of RA T cells to IL-2 was significantly less than that of controls. These results suggest that the defect in the generation of AMLR killer cells in patients with active RA may be due in part to defective production of IL-2 and a lesser sensitivity of RA T cells to IL-2.

Characterization of the defective autologous mixed lymphocyte response in rheumatoid arthritis

In order to characterize the autologous mixed lymphocyte response (AMLR) in patients with rheumatoid arthritis (RA) and to define the relationship with disease activity, peripheral blood T lymphocytes were stimulated with either a B lymphocyte-enriched (B cells) or a macrophage-enriched (macrophages) population. A significant reduction (P less than 0.01 to P less than 0.001) of T cell proliferation stimulated both by B cells and macrophages was observed in patients with active disease. The B lymphocytes were significantly less stimulatory (P less than 0.02 to P less than 0.001) than macrophages in the patients compared with the controls. In the normal controls, macrophages in higher concentrations were capable of suppressing the B lymphocyte-stimulated AMLR, but macrophages from patients with RA were not excessively suppressive. A significant association (P less than 0.02) was observed between disease activity and the AMLR. Using the B-enriched population, the AMLR proliferative response was significantly associated (P less than 0.001) with the production of interleukin-2. Defects in proliferation could only be partially restored by the addition of interleukin-2. These data indicate that the defective AMLR observed in patients with RA is related to disease activity and is associated with altered cellular interactions among T lymphocytes, macrophages, and the B lymphocyte-enriched population.

Lysis of tumor biopsy cells by blood lymphocyte subsets of various densities. Autologous and allogeneic studies

Blood lymphocyte subsets of various densities from 14 healthy donors and 25 patients with solid tumors were used in tests for cytotoxicity against allogeneic or autologous tumor cells. The allogeneic combinations comprised 36 tests on 28 tumors. In these the unmanipulated total lymphocyte population was cytotoxic in one experiment. In tests with density-separated subsets, 16 experiments were positive. The lytic effect resided in the light subsets. Auto-tumor lysis was detected in 7 of 25 cases, when the total lymphocyte population was used. Eleven additional tests showed cytotoxicity with the separated subsets. The autologous tumor cells were damaged by the light lymphocytes of 15 patients. Of these patients, 6 had cytotoxic cells also in the high-density subset. In seven cases auto-tumor lysis was exerted only by the dense lymphocytes. Thus, in 13 cases the profile of auto-tumor lysis differed from that observed with the allogeneic combinations and against K562. Pretreatment of the effectors with Hu-IFN-alpha enhanced or induced cytotoxicity in the light lymphocytes, against both allogeneic and autologous tumors, while the dense subset was rarely potentiated. The autologous system may represent an immune situation and therefore it is not unexpected that the active cells should have different phenotypic characteristics from those of the operationally natural killer system.

Mouse monoclonal antibodies can nonspecifically inhibit the proliferation of human T-cell growth factor-dependent T cells

A large series of mouse monoclonal antibodies was found to inhibit the proliferation of T-cell growth factor (TCGF)-dependent human T-cell blasts as measured by the incorporation of tritiated thymidine. The specificity of the antibody appeared to be irrelevant for inhibition and two T-cell-specific antibodies did not prevent the absorption of TCGF by treated T cells. It is suggested that the antibodies function by the indirect release of suppressor factors by Fc receptor-bearing TCGF-dependent cells.

Density separation of chronic lymphocytic leukemia cells: low-density non-T cells are efficient stimulator cells in allogeneic and autologous mixed leukocyte reaction

Unseparated mononuclear cells and E rosette-depleted non-T cells from a majority of patients with chronic lymphocytic leukemia (CLL) were found to be weak stimulators in the allogeneic mixed-leukocyte reaction (MLR). However, a minor population (1-5%) of highly active stimulator cells could be isolated from all patients studied by buoyant density centrifugation using discontinuous gradients of Percoll. The same low-density non-T-cell fraction also stimulated autologous T-cell proliferation in the autologous mixed-leukocyte reaction (AMLR). In contrast, Percoll-separated high-density non-T cells, including the leukemic B-cell pool, were completely inactive as stimulators in AMLR. These results suggest that the presence of efficient stimulator cells among CLL mononuclear cells may be masked by the large number of nonstimulating leukemic B cells.