Characterization of a novel differentiation antigen complex recognize by a monoclonal antibody (A-1A5): unique activation-specific molecular forms on stimulated T cells

By using a single monoclonal antibody, a novel glycoprotein complex composed of at least three distinct bands was defined on the surface of mitogen- or alloantigen-stimulated T cells. These bands (210,000, 165,000, and 130,000 Mr) were not disulfide linked and could be radio-labeled with 125I or 35S-methionine and readily detected by immunoprecipitation with the monoclonal antibody A-1A5. Only approximately 20% of normal T cells (E rosette positive) and approximately 47% non-T cells (E rosette negative) were reactive with A-1A5. However, upon activation of T cells, the amount of A-1A5 binding per cell and the percentage of positive cells significantly increased. This increase was most pronounced in the activated cell subpopulations currently undergoing cell division (S, G2, and M phases), which became 79% A-1A5 positive (after PHA stimulation) and 99% A-1A5 positive (in long-term culture with alloantigen and IL2). Resting lymphocytes contained only the 130,000 Mr band reactive with A-1A5. The two other bands (210,000 and 165,000 Mr) were markers for T cell activation and only appeared several days after T cell stimulation and became especially prominent after the addition of exogenous IL 2. All T lymphoblastoid cell lines tested expressed at least the lower bands (130,000 Mr), and the T cell line HSB also expressed one of the activation-related larger proteins (165,000 Mr). B lymphoblastoid cell lines expressed only a very weak lower band (130,000 Mr), and the cell line U-937 (in the monocyte-macrophage lineage) expressed only a single band (145,000 Mr) not aligned with any of the bands found on lymphoid cells. The estimated number of A-1A5 binding sites per cell was much higher on U-937 (11 X 10(5)), and generally higher on other cell lines of myeloid lineage (1 to 4 X 10(5)) than on lymphoid cell lines (0.2 to 1.3 X 10(5)).

Characterization of a novel differentiation antigen complex recognize by a monoclonal antibody (A-1A5): unique activation-specific molecular forms on stimulated T cells

By using a single monoclonal antibody, a novel glycoprotein complex composed of at least three distinct bands was defined on the surface of mitogen- or alloantigen-stimulated T cells. These bands (210,000, 165,000, and 130,000 Mr) were not disulfide linked and could be radio-labeled with 125I or 35S-methionine and readily detected by immunoprecipitation with the monoclonal antibody A-1A5. Only approximately 20% of normal T cells (E rosette positive) and approximately 47% non-T cells (E rosette negative) were reactive with A-1A5. However, upon activation of T cells, the amount of A-1A5 binding per cell and the percentage of positive cells significantly increased. This increase was most pronounced in the activated cell subpopulations currently undergoing cell division (S, G2, and M phases), which became 79% A-1A5 positive (after PHA stimulation) and 99% A-1A5 positive (in long-term culture with alloantigen and IL2). Resting lymphocytes contained only the 130,000 Mr band reactive with A-1A5. The two other bands (210,000 and 165,000 Mr) were markers for T cell activation and only appeared several days after T cell stimulation and became especially prominent after the addition of exogenous IL 2. All T lymphoblastoid cell lines tested expressed at least the lower bands (130,000 Mr), and the T cell line HSB also expressed one of the activation-related larger proteins (165,000 Mr). B lymphoblastoid cell lines expressed only a very weak lower band (130,000 Mr), and the cell line U-937 (in the monocyte-macrophage lineage) expressed only a single band (145,000 Mr) not aligned with any of the bands found on lymphoid cells. The estimated number of A-1A5 binding sites per cell was much higher on U-937 (11 X 10(5)), and generally higher on other cell lines of myeloid lineage (1 to 4 X 10(5)) than on lymphoid cell lines (0.2 to 1.3 X 10(5)).

Cytotoxic T cells directed against HLA-DR antigens and their surface proteins

The authors review their recent research involving the generation of cytotoxic T lymphocytes (CTL) directed against HLA-DR antigens. A mouse anti-human xenogeneic system first suggested that HLA-DR antigens could be recognized by CTL. Human allogeneic CTL specific for HLA-DR6 were generated and found to be OKT4+. The fact that these CTL were OKT4+ while anti HLA-A,B CTL were OKT8+ suggested that these T cell surface antigens may be involved in MHC antigen recognition; ie, they may be part of the T cell receptor. These OKT4+, HLA-DR specific CTL were further used to generate monoclonal antibodies (1) which block cytolysis and define novel antigens involved in the CTL-target interaction and (2) which define an antigenic complex on alloantigen activated T cells.

Three distinct antigens associated with human T-lymphocyte-mediated cytolysis: LFA-1, LFA-2, and LFA-3

Monoclonal antibodies were prepared to anti-HLA-DR cytolytic T lymphocytes (CTLs) and screened for inhibition of CTL-mediated killing. Binding of monoclonal antibodies to four types of molecules, LFA-1, LFA-2, LFA-3, and HLA-DR, inhibited killing, suggesting that these molecules participate in the CTL-target cell interaction. The antigens were characterized by immunoprecipitation, crosslinking, NaDodSO4/polyacrylamide gel electrophoresis, and immunofluorescence flow cytometry. The LFA-1 antigen contains alpha and beta polypeptide chains of Mr 177,000 and 95,000 that are noncovalently associated in an alpha 1 beta 1 structure. It is present on both B and T lymphocytes and marks subpopulations that differ in quantitative expression. Human LFA-1 appears to be the homologue of mouse LFA-1. Human LFA-2 is of Mr 49,000 with a minor component of Mr 36,000. It is expressed on CTL lines but not on a B-cell line and in peripheral blood preferentially on T lymphocytes. Human LFA-3 is of Mr 60,000 and is expressed on both B and T lymphocytes.

Assembly of the functional membrane attack complex of human complement: formation of disulfide-linked C9 dimers

The 158,000 Mr protein, previously designated C5c, present in fully assembled complement (C) membrane attack complexes (MC5b-9) has been identified as a disulfide-bonded dimer of C9. This conclusion was based on the observations that: (i) a portion of the 125I-radiolabeled precursor C9 incorporated into MC5b-9 complexes comigrated with the 158,000 Mr protein band in NaDodSO4/polyacrylamide slab gels; (ii) monospecific antisera produced against native C9 and the 158,000 Mr protein immunologically crossreacted with monomeric native C9 by double immunodiffusion and with monomeric C9 and the 158,000 Mr protein on immunoreplication procedures; and (iii) two-dimensional NaDodSO4/polyacrylamide slab gel electrophoresis, in which the second dimension was conducted under reducing conditions, revealed that the 158,000 Mr protein contained two identical 71,000 Mr subunits which comigrated with monomeric C9. Molar ratio estimates indicated that 1 mol of C5b, C9 dimer, C6, C7, and C8 and 3-4 mol of C9 monomer were present per MC5b-9 complex. Each fully assembled membrane-bound MC5b-9 complex would therefore have a calculated Mr of 982,000. The presence of C9 dimers in the hemolytically active 29S dimeric form of the MC5b-9 complex and the absence of C9 dimers in the hemolytically inactive 23S monomeric form of the fluid phase SC5b-9 complex strongly suggest an important role for C9 dimer formation in MC5b-9 complex structure and function. The most probable function of C9 dimers would be the formation of intercomplex disulfide crosslinks which would provide a mechanism to stabilize the assembly of MC5b-9 into aggregates of increasing size on the target membrane surface which would thus be responsible for the observed pore size heterogeneity of functional C lesions.

Mechanisms of lymphocyte-mediated cytotoxicity. I. The effects of anti-human lymphotoxin antisera on the cytolysis of allogeneic B cell lines by MLC-sensitized human lymphocytes in vitro

Goat and rabbit anti-human lymphotoxin sera, IgG and F(ab')2 reagents were investigated for their capacity to effect a specific alloimmune lymphocyte-mediated cytotoxic reaction. The cytotoxic reaction employed human peripheral blood or adenoid lymphocytes sensitized in MLC to allogeneic B lymphocyte cell lines and lysis was measured in a short-term 51Cr-release assay. A polyspecific anti-LT sera (anti-WS), made against unfractionated whole supernatants from lectin-activated lymphocytes and its IgG and F(ab')2 fragments, was found to be a potent inhibitor of this reaction when the anti-WS reagent was present throughout the assay period. Absorption studies indicated the anti-WS was inhibiting cytolysis at the level of effector cell or its products. Two broadly defined antibody specificities were involved in the cytolytic-inhibitory activity of the polyspecific anti-LT; i) antigens present on the normal lymphocyte cell surface; and ii) lymphocyte surface antigens associated with activated cells. These results correlate with the previously defined antigenic structure of the LT Cx and alpha H classes. Anti-LT sera reactive with the smaller m.w. alpha and beta classes and subclasses were not inhibitory, although the anti-beta sera showed a moderate enhancing activity. The results indicated that several anti-LT antibody specificities may be required to inhibit alloimmune cytolysis. The results suggest LT molecules may mediate lymphocyte-induced alloimmune cytolysis as a multi-component toxin system, rather than as an individual toxin.

Mechanisms of lymphocyte-mediated cytotoxicity. I. The effects of anti-human lymphotoxin antisera on the cytolysis of allogeneic B cell lines by MLC-sensitized human lymphocytes in vitro

Goat and rabbit anti-human lymphotoxin sera, IgG and F(ab')2 reagents were investigated for their capacity to effect a specific alloimmune lymphocyte-mediated cytotoxic reaction. The cytotoxic reaction employed human peripheral blood or adenoid lymphocytes sensitized in MLC to allogeneic B lymphocyte cell lines and lysis was measured in a short-term 51Cr-release assay. A polyspecific anti-LT sera (anti-WS), made against unfractionated whole supernatants from lectin-activated lymphocytes and its IgG and F(ab')2 fragments, was found to be a potent inhibitor of this reaction when the anti-WS reagent was present throughout the assay period. Absorption studies indicated the anti-WS was inhibiting cytolysis at the level of effector cell or its products. Two broadly defined antibody specificities were involved in the cytolytic-inhibitory activity of the polyspecific anti-LT; i) antigens present on the normal lymphocyte cell surface; and ii) lymphocyte surface antigens associated with activated cells. These results correlate with the previously defined antigenic structure of the LT Cx and alpha H classes. Anti-LT sera reactive with the smaller m.w. alpha and beta classes and subclasses were not inhibitory, although the anti-beta sera showed a moderate enhancing activity. The results indicated that several anti-LT antibody specificities may be required to inhibit alloimmune cytolysis. The results suggest LT molecules may mediate lymphocyte-induced alloimmune cytolysis as a multi-component toxin system, rather than as an individual toxin.

A Physicochemical and Immunologic Comparison of the Cell Growth Inhibitory Activity of Human Lymphotoxins and Interferons in vitro

The physicochemical, immunologic, and biologic relationships between human lymphotoxins (LT) and interferons (IF) present in supernatant fluids from lectin-stimulated peripheral blood lymphocytes (PBL) and a continuous B-lymphoblastoid cell line (PGLC-33h) were analyzed. LT activity obtained from lectin-activated PBL could not be resolved from IF activity by gel filtration chromatography. LT activity eluted in multiple peaks of activity at 70 to 90,000, and 40 to 50,000 m.w., characteristic of α and β LT, respectively. IF activity in these supernatant fluids eluted as a broad band between 35 and 80,000 m.w., also suggestive of molecular heterogeneity. In contrast, this m.w. heterogeneity was not observed in LT and IF activities obtained from the PGLC-33h cell line. LT and IF eluted as separate peaks of activity at 90,000 and 25,000 m.w., respectively. In addition, acid and heat lability of PGLC-33h IF suggested similarity to type II IF. Immunologic studies, with a rabbit anti-α class serum that neutralized LT activity from both PBL and PGLC-33h, did not affect IF activity from either of these sources.

Supernatant fluids from PGLC-33h cultures were also capable of inhibiting the proliferation of HeLa cells in vitro. The growth inhibitory activity was attributed to LT- and IF-like molecules. This evidence suggests that although cytotoxic and anti-viral activities were due to separate molecules, LT and IF have overlapping biologic activities in their ability to inhibit the proliferation of cells in vitro.

A physicochemical and immunologic comparison of the cell growth inhibitory activity of human lymphotoxins and interferons in vitro

The physicochemical, immunologic, and biologic relationships between humam lymphotoxins (LT) and interferons (IF) present in supernatant fluids from lectin-stimulated peripheral blood lymphocytes (PBL) and a continuous B-lymphoblastoid cell line (PGLC-33h) were analyzed. LT activity obtained from lectin-activated PBL could not be resolved from IF activity by gel filtration chromatography. LT activity eluted in multiple peaks of activity at 70 to 90,000, and 40 to 50,000 m.w., characteristic of alpha and beta LT, respectively. IF activity in these supernatant fluids eluted as a broad band between 35 and 80,000 m.w., also suggestive of molecular heterogeneity. In contrast, this m.w. heterogeneity was not observed in LT and IF activities obtained from the PGLC-33h cell line. LT and IF eluted as separate peaks of activity at 90,000 and 25,000 m.w., respectively. In addition, acid and heat lability of PGLC-33h IF suggested similarity to type II IF. Immunologic studies, with a rabbit anti-alpha class serum that neutralized LT activity from both PBL and PGLC-33h, did not affect IF activity from either of these sources. Supernatant fluids from PGLC-33h cultures were also capable of inhibiting the proliferation of HeLa cells in vitro. The growth inhibitory activity was attributed to LT- and IF-like molecules. This evidence suggests that although cytotoxic and anti-viral activities were due to separate molecules, LT and IF have overlapping biologic activities in their ability to inhibit the proliferation of cells in vitro.

Duane's uniocular micro-tremor or superior oblique myokymia of Hoyt and Keane

Two cases of intermittent unilateral motor disturbance of the superior oblique muslce are presented and compared with cases reported previously by Duane, Clark and Hoyt & Keane and briefly mentioned by Duke-Elder in his System of Ophthalmology. The first case is a girl with longstanding history of oscillopsia, vertical and tortional oscillatory diplopia. No abnormal eye movements were observed but objective evidence of the disturbance was obtained in the form of electromyography during which relationship of the superior oblique was established. In contrast, the second case experienced episodes of static vertical and tortional diplopia similar to the case reported to by Clark. Again the relationship in the condition was unilateral involving the superior oblique muscle. There was no corroboratory evidence to support the diagnosis of an intermittent superior oblique tendon sheath syndrome. Hoyt & Keane's theory based on their electromyography findings that the lesion is in the lower motor neuron unit is reported and the significance of the oscillopsia as corroboratory evidence is discussed.

Iris involvement in leukaemia

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