The interaction of mammalian cells with antibodies. I

In vitro studies of mammalian somatic cell variation. II. Isoimmune cytotoxicity with a cultured mouse lymphoma and selection of resistant variants

When long term cultures of mouse lymphoma cells, known to possess the isoantigenic phenotype determined by the H-2^d allele, are incubated with anti H-2d isoantibody and guinea pig complement, slightly more than 99 per cent of cells are killed under optimal conditions. Growth in mass culture and colony formation by single cells after incubation with isoantibody and complement are employed to assess the cytotoxic effect. The cytotoxic action of isoantibody is complement-dependent, for viability of cells exposed to antibody alone is unaltered. When excess isoantibody and optimum concentrations of complement are used, killing begins as soon as these reagents are mixed with the cells, and no further killing occurs after 5 to 15 minutes at 37°C. About 80 per cent of cells are killed with an isoantiserum containing antibody to two isoantigenic components of the H-2d complex. That the cytotoxic action is mediated through the H-2 isoantigen is shown by (a) isoantiserum containing only anti H-2d antibody produces maximal cell killing, and (b) isoantiserum from which anti H-2d antibody has been removed by absorption loses all cytotoxic activity. Variant cells resistant to the cytotoxic action of anti H-2d isoantibody were isolated from lymphoma cell populations surviving multiple exposures to isoantibody and complement. These variants can be distinguished morphologically from the isoantibody-sensitive parent cell line. Although variants are resistant to anti H-2d isoantibody, these cells possess H-2d isoantigen but in a lower concentration than found in cells of the parent line. The basis for resistance to cytotoxic isoantibody is discussed.

The role of humoral antibodies in rejection of skin homografts in rabbits. II. Passive transfer of transplantation immunity by sensitized lymph node cells within diffusion chambers

Passive transfer of transplantation immunity by means of sensitized lymphoid cells enclosed within diffusion chambers has been accomplished in non-radiated and radiated rabbits. This result, together with other data available in the literature, suggests that humoral antibodies play an important role in rejection of skin homografts in the rabbit.

A fine-structure deletion map of human chromosome 11p: analysis of J1 series hybrids

Deletion analysis offers a powerful alternative to linkage and karyotypic approaches for human chromosome mapping. A panel of deletion hybrids has been derived by mutagenizing J1, a hamster cell line that stably retains chromosome 11 as its only human DNA, and selecting for loss of MIC1, a surface antigen encoded by a gene in band 11p13. A unique, self-consistent map was constructed by analyzing the pattern of marker segregation in 22 derivative cells lines; these carry overlapping deletions of 11p13, but selectively retain a segment near the 11p telomere. The map orders 35 breakpoints and 36 genetic markers, including 3 antigens, 2 isozymes, 12 cloned genes, and 19 anonymous DNA probes. The deletions span the entire short arm, dividing it into more than 20 segments and define a set of reagents that can be used to rapidly locate any newly identified marker on 11p, with greatest resolution in the region surrounding MIC1. The approach we demonstrate can be applied to map any mammalian chromosome. To test the gene order, we examined somatic cell hybrids from five patients, whose reciprocal translocations bisect band 11p13; these include two translocations associated with familial aniridia and two with acute T-cell leukemia. In each patient, the markers segregate in telomeric and centromeric groups as predicted by the deletion map. These data locate the aniridia gene (AN2) and a recurrent T-cell leukemia breakpoint (TCL2) in the marker sequence, on opposite sides of MIC1. To provide additional support, we have characterized the dosage of DNA markers in a patient with Beckwith-Wiedemann syndrome and an 11p15-11pter duplication. Our findings suggest the following gene order: TEL - (HRAS1, MER2, CTSD, TH/INS/IGF2, H19, D11S32) - (RRM1, D11S1, D11S25, D11S26) - D11S12 - (HBBC, D11S30) - D11S20 - (PTH, CALC) - (LDHA, SAA, TRPH, D11S18, D11S21) - D11S31 - D11S17 - HBVS1 - (FSHB, D11S16) - AN2 - MIC1 - TCL2 - delta J - CAT - MIC4 - D11S9 - D11S14 - ACP2 - (D11S33, 14L) - CEN. We have used the deletion map to show the distribution on 11p of two centromeric repetitive elements and the low-order interspersed repeat A36Fc. Finally, we provide evidence for an allelic segregation event in the hamster genome that underlies the stability of chromosome 11 in J1. The deletion map provides a basis to position hereditary disease loci on 11p, to distinguish the pattern of recessive mutations in different forms of cancer and, since many of these genes have been mapped in other mammalian species, to study the evolution of a conserved syntenic group.

The kinetics of interaction between lymphocytes and magnetic polymer particles

Magnetic polymer-coated particles linked to antibodies are considered to be an efficient rosetting matrix for immunoselection. We have shown that a 20:1 bead:target cell ratio and a 90 min incubation period are the optimal conditions for specific binding of monoclonal antibody-labelled cells to goat anti-mouse IgG-coated beads. Higher ratios or longer incubation periods resulted in considerable non-specific binding. Characterisation of the optimal conditions for specific depletion of lymphocyte subpopulations showed that (a) a range of bead:target cell ratios and incubation periods can be used, with resulting high efficiency and specificity; (b) multiple monoclonal antibodies can be used simultaneously for the depletion of diverse lymphocyte subpopulations; (c) non-specific bead-to-cell binding does not affect the specificity and efficiency of magnetic depletion; (d) specific binding of one bead only was adequate for effective magnetic separation. These findings define the most economical, specific and efficient conditions of use of beads for negative immunoselection but preclude the use of beads as an analytical rosetting medium.

Natural killer cells in peripheral blood and the mixed lymphocyte response: interaction with the transferrin receptor

Several reports suggest that natural killer (NK) cells recognize the transferrin receptor (TFR) as a target for killing, and that natural cytotoxicity may be involved in the control of stem cell proliferation in bone-marrow. This study tested whether NK-cell recognition of the TFR on activated lymphocytes plays a role in the control of peripheral immune responses. Six lymphoid lines were created from a single individual, and used as targets for cytotoxicity assays, using either peripheral blood mononuclear cells, or mixed lymphocyte reaction (MLR)-derived effectors. The cells responsible for killing were predominantly Leu-11+Leu-7+ NK cells, though CD3+ cells accounted for about 25% of cytotoxicity from MLR. No correlation was observed between TFR density and NK susceptibility when using all six cell lines. Specifically increasing the density of TFR on a single cell line failed to increase susceptibility to NK, suggesting that the TFR does not act as a major target for natural cytotoxicity directed at lymphoid cells. Furthermore, the relatively low levels of killing observed indicate that activated NK populations that accumulate at sites of immune response are unlikely to play a direct immunoregulatory role.

Polymer microbeads in immunology

Synthetic polymer microbeads have been studied extensively and the required properties, including monodispersity and size range 0.05-10 microns can best be achieved by radiation polymerization based on methacrylate derivatives. Fluorochrome-conjugated beads can be used for cell surface markers and simultaneously to study phagocytosis. The paper reviews some of these applications. Cell separation techniques are also described. Future possibilities for immunological and cell biology studies are discussed.

Cell separation using positive immunoselective techniques

Positive immunoselection is the direct selection and recovery of cells which express a given specificity from among a heterogeneous group of contaminating cells. A variety of methods are available to effect such separations. The principles of affinity chromatography, using solid-phase matrices or cellular immunoadsorbents, are extensively used. Liquid-phase positive immunoselection can also be performed using either a fluorescence-activated cell sorter or by using 'cellular engineering' to protect a cell from an otherwise noxious environment. The enzyme catalase coupled to specific antibody has been used for this purpose and renders cells resistant to hydrogen peroxide. The various positive immunoselection techniques available are reviewed and evaluated in the following report.

Positive immunoselection using antibody-enzyme complexes

We have developed an immunoselection technique using catalase-anti-catalase complexes coupled to specific antibodies to protect antigen positive target cells from the lethal effects of H2O2. The antibody-enzyme complexes are bound to the target cells through an antibody bridge with specificity for both the complexes and an anti-target cell antibody. In a model system, Thy-1 positive (RL male 1-3) cells were protected by incubation with rabbit anti-brain-associated theta antigen (BAT), sheep anti-rabbit IgG [F(ab)'2] and catalase-anti-catalase complexes. The amount and composition of the complexes adhering to the cells were measured by dual radiolabeling of the catalase and anti-catalase immunoglobulin. This technique provides a means of identifying and isolating large numbers of cells bearing any antigen for which specific antisera are available.

Precise localization of human beta-globin gene complex on chromosome 11

Cloned DNA probes were used in combination with a panel of five hybrid cell clones containing a series of different terminal deletions in human chromosome 11 to map precisely the human hemoglobin beta and delta chain structural genes contained on this chromosome. The region of deletion in each clone of the panel has been defined by biochemical, immunologic, and cytogenetic markers. DNA from clones containing successively larger terminal deletions was tested with appropriate DNA probes to determine the point on the chromosome at which DNA for these two closely linked hemoglobin genes is deleted. These genes, and by inference the closely linked G gamma and A gamma globin genes as well, have been assigned to the intraband region 11p1205 leads to 11p1208 on the short arm of chromosome 11, an interval containing approximately 4500 kilobases of DNA. The approach appears to have potential for even greater resolution and reasonably wide applicability for gene mapping.

Role of the microfibrillar system in knob action of transformed cells

Transformed cells often display knobs (or blebs) distributed over their surface throughout most of interphase. Scanning electron microscopy (SEM) and time-lapse cinematography on CHO-K1 cells reveal roughly spherical knobs of 0.5-4 micron in diameter distributed densely around the cell periphery but sparsely over the central, nuclear hillock and oscillating in and out of the membrane with a period of 15-60 sec. Cyclic AMP derivatives cause the phenomenon of reverse transformation, in which the cell is converted to a fibroblastic morphology with disappearance of the knobs. A model was proposed attributing knob formation to the disorganization of the jointly operating microtubular and microfilamentous structure of the normal fibroblast. Evidence for this model includes the following: 1) Either colcemid or cytochalasin B (CB) prevents the knob disappearance normally produced by cAMP, and can elicit similar knobs from smooth-surfaced cells; 2) knob removal by cAMP is specific, with little effect on microvilli and lamellipodia; 3) immunofluorescence with antiactin sera reveals condensed, amorphous masses directly beneath the membrane of CB-treated cells instead of smooth, parallel fibrous patterns of reverse-transformed cells or normal fibroblasts; 4) transmission electron microscopy (TEM) of sections show dense, elongated microfilament bundles and microtubules parallel to the long axis of the reverse-transformed CHO cell, but sparse, random microtubules throughout the transformed cell and an apparent disordered network of 6-nm microfilaments beneath the knobs; 5) cell membranes at the end of telophase, when the spindle disappears and cleavage is complete, display typical knob activity as expected by this picture.

In vitro effects of pemphigus antibodies on skin

Acantholysis occurring in rhesus monkey skin explants cultured on sera of 9 pemphigus patients was found to be largely dependent on the titre of intercellular antibody, and not on the participation of complement. Skin explants cultured on normal human sera and pemphigoid sera failed to give rise to intercullular staining or to develop lesions. Six of eight 'negative' pemphigus sera with intercellular antibody titres of less than 20 on skin (and titres ranging from 20 to 160 on monkey esophagus) reacted with the skin explants as revealed by direct immunofluorescence with an anti-IgG conjugate. The binding of antibodies from 3 of these 6 reactive sera resulted in some pathological changes in the explants. At least two of these 3 'negative' sera came from pemphigus patients with skin lesions.

Further studies on hybrid cell-surface antigens associated with human chromosome 11

A new human immunogenetic cell-surface activity associated with human chromosome 11 in the AL human-Chinese hamster ovary cell hybrid is described. Like a1, but not a2, it is present on the human erythrocyte. By mutagenesis and selection, specific, stable, variants of the AL hybrid have been prepared exhibiting various combinations of a1, a2, a3, and lactic dehydrogenase A activities. The antigens of the AL system can be demonstrated by the horseradish peroxidase system which offers a promising approach to scanning of tissue cells.

Genetics of cell-surface antigens: regional mapping of three components of the human cell-surface antigen complex, AL, on chromosome 11

Cytogenetic analysis has been performed on a series of deletion mutations on human chromosome 11 of AL hybrid clones in which specific markers have been lost as a result of treatment with mutagenic agents. Such analysis has localized the three previously identified components of the AL cell-surface antigen complex to the indicated regions of chromosome 11: a1 and a3:11p13 leads to 11pter; a2:11q13 leads to 11qter. Using these methodologies human lactic dehydrogenase A localization on the short arm as reported by others has been confirmed. Evidence is presented provisionally assigning this gene to 11p13 leads to 11pter.

Genetics of somatic mammalian cells: genetic, immunologic, and biochemical analysis with Chinese hamster cell hybrids containing selected human chromosomes

Through hybridization of specific Chinese hamster cell auxotrophs with human cells and selection in media lacking the nutritional supplements required by the former cells, a series of stable hybrid clones can be prepared. These hybrids have genomes consisting of a common part--the complete or almost complete set of Chinese hamster chromosomes, plus a variable part--one or a few human chromosomes. The identity of the human chromosomes can be varied by utilizing different Chinese hamster auxotrophs and the appropriate selective media. The human chromosomes present can be determined by a combination of cytogenetic analysis with chromosome banding and testing for specific human marker genes. Hybrids containing single human chromosomes 11 and 12 and the combination of both 11 and 12 are described. The system appears to lend itself to various studies such as identification of human cell surface antigens, determination of their chromosomal loci, measurement of their distribution among cells of normal human tissues, study of interrelations among syntenic and asyntenic genes, and mutational analysis of the human genome.

Nephrotic syndrome, monoclonal gammopathy and auto-immune hyperlipidaemia

Hyperlipidaemia, glomerulonephritis and IgG λ monoclonal gammopathy were found to be associated in two patients (Ler. and Lac.). A severe atherosclerosis was also present in the former patient. After a purification–activation procedure active IgG λ was obtained from the serum chylomicra and from the ammonium sulphate-precipitated serum gamma-globulins. In passive haemagglutination tests, including inhibition tests, the IgG λ Ler. reacted specifically with the protein moiety of human low density lipoproteins (LDL) and the IgG λ Lac. reacted with human, rat and rabbit very low density lipoproteins (VLDL) as well as with human serum albumin (HSA). These IgG λ behaved like autoantibodies though no activity was found in whole serum, in which they are probably blocked by the corresponding antigens. They are very similar, although not identical, to the autoantibodies found in auto-immune hyperlipidaemia (AIH) and it is proposed that in these patients the hyperlipidaemia is a variety of AIH. Finally it is suggested that the hyperlipidaemia associated with glomerulonephritis chiefly in the nephrotic syndrome may sometimes be AIH. If this is the case the renal lesions and the hyperlipidaemia may be different expressions of an immune complex disease which may also lead to other tissue lesions such as atherosclerosis.

Human antigen and enzyme markers in man-Chinese hamster somatic cell hybrids: evidence for synteny between the HL-A, PGM3, ME1, and IPO-B loci

In man-Chinese hamster somatic cell hybrids the segregation of the loci for 27 human enzyme markers and the species-specific surface antigens, including the HL-A histocompatibility antigens, was studied. The results show a synteny of the human loci for phosphoglucomutase 3, cytoplasmic malic enzyme, tetrameric indophenol oxidase, and HL-A. Furthermore, evidence is presented that the loci for the human species-specific antigens are distributed over several chromosomes.

Genetics of somatic mammalian cells: lethal antigens as genetic markers for study of human linkage groups

The antigen that causes killing of at least 98% of a human cell population treated with a 1% solution of a specific rabbit antiserum in the presence of complement is a sensitive genetic marker. The rapid loss of human chromosomes in human-Chinese hamster cell hybrids makes possible a convenient test of linkage relationships with this marker. Hybrid clones with and without the lethal antigen were isolated and analyzed. In 76 clones and subclones studied, 41 carried both the lethal antigen and the lactic dehydrogenase-A marker, 35 carried neither, and no clones contained only one of the two markers. In contrast to this clear demonstration of linkage, absence of linkage was found between the lethal antigen and the following markers: Lactic dehydrogenase B, NAD-dependent malic dehydrogenase, NADP-dependent malic dehydrogenase, glucose-6-phosphate dehydrogenase, phosphoglucomutase, glutamate oxaloacetate transaminase, indophenol oxidase, glucose phosphate isomerase, proline, inositol, hypoxanthine B, and glycine A. This lethal antigen appears to be carried on a single human autosome.

Further changes in differentiation state accompanying the conversion of Chinese hamster cells of fibroblastic form by dibutyryl adenosine cyclic 3':5'-monophosphate and hormones

The morphological conversion in vitro of Chinese hamster ovary cells to a fibroblast form by a relatively large amount of dibutyryl adenosine cyclic 3':5'-monophosphate, or by a combination of small amounts of this compound and testosterone, is attended by appearance of the following additional properties: acquisition of strict contact inhibition of growth; reorientation of the random growth pattern into one in which cells grow parallel to their long dimension; disappearance of the randomly distributed, knob-like, pseudopodal structures around the cell periphery; induction of collagen synthesis; and decrease in the ability to be agglutinated and rounded up by plant agglutinins and specific cell antibodies. The changes in these characteristics are consistent with the conversion from a malignant to a normal fibroblastic state. This conversion is under genetic control, as demonstrated by the production of specific mutants with altered characteristics. The response to testosterone is specific since steroids like estradiol and hydrocortisone are inactive, and others have limited activity. Some prostaglandins are equal in activity to testosterone and 5alpha-dihydrotestosterone. This system appears useful in study of the regulation of phenotypic expression in mammalian cells.

Effect of anticellular serum on the attachment of enteroviruses to HeLa cells

Anticellular serum (ACS), in the absence of an active complement system, was shown to inhibit the attachment of poliovirus types 1 and 2, echovirus type 6, and coxsackievirus types A13, B1, and B3 to viral receptors of live HeLa cells. This is the first report to provide evidence that ACS has an inhibitory effect on the interaction between host cells and coxsackieviruses of group B. The titer of inhibitory activity of ACS varied inversely with the cell concentration used, the reaction being virtually completed after an incubation period of 30 min at 37 C. The inhibitory activity of ACS persisted for more than 4 hr at 37 C, and was shown to be reversible at pH 2.0, revealing that although the receptors for attaching virus were inactivated by ACS the inactivation was not permanent. These findings are consistent with the concept that antibodies in the ACS combine with and blockade viral receptors located at the cell surface. An antiserum with a specificity for inhibiting attachment of coxsackievirus B1 was obtained by dual absorption of ACS with cells saturated with coxsackievirus type B3 and chymotrypsin-treated cells. These findings offer an approach whereby the antigenic relationship of viral receptors to other constituents of the cell surface can be studied.

Lymphocyte-transforming activity of homologous and heterologous antisera to rabbit leucocytes

Two out of nine rabbits receiving a course of immunization with homologous leucocytes produced antisera which caused blast formation and stimulated DNA synthesis of donor lymphocytes in vitro. Of the seven rabbits which failed to produce active antisera three had received only a short immunization course. The active antisera `transformed' lymphocytes from some rabbits but not those of others. This stimulatory effect was not related to the red cell types or the γ-globulin allotypes of the rabbits.

Heterologous antisera raised to rabbit leucocytes in rats and guinea-pigs were cytotoxic to rabbit leucocytes in vitro and also caused leucoagglutination but never stimulated DNA synthesis and blast formation.

EFFECT OF ANTIBODY ON HETEROLOGOUS AND HOMOLOGOUS CELLS IN TISSUE CULTURE

In order to compare antibody against heterologous and homologous tissue in the same serum, rabbits were immunized with rat kidney and complete adjuvant. The resulting sera showed antibody against both rat and rabbit kidney. Cultures of rat kidney cells were killed by exposure to these sera. A concentration of 0.3 per cent γ globulin (ammonium sulphate fraction) was adequate to kill cultures in the absence of complement, but smaller concentrations were effective when guinea-pig complement was added. The cell surfaces were shown to have taken up antibody by the fluorescent antibody technique. Cytoplasmic staining could only be shown in cells which had previously been injured by freezing and thawing or by fixation. Rabbit kidney cells in culture were unaffected when exposed to whole rabbit anti-rat serum, but were killed and their cell membranes stained on exposure to γ globulin derived by (NH₄)₂SO₄-fractionation from such serum and having the same complement-fixation titre as the parent serum. At least 0.6 per cent γ globulin had to be added to kill rabbit cell cultures. It was found that normal rabbit serum had a partial protective effect against this antibody. Fractionation of sera by gradient centrifugation or chromatography on DEAE-cellulose showed that while antibody against heterologous tissue was found both in the 7S γ globulin and macroglobulin fractions, antibody against homologous tissue was confined to the latter. It is considered that the findings do not support a concept of an in vivo pathogenic role for circulating antibody.