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Biomedical subjects

I Sandlie

Publications and source records attributed to I Sandlie.

At least 37 records · Page 2Linked to original sources
PubMed1998

Activation of complement by human IgG1 and human IgG3 antibodies against the human leucocyte antigen CD52.

Activation of the complement cascade by immunoglobulin G (IgG) plays a major role in the host defense against pathogens. Using recombinant human antibodies specific for the leucocyte antigen CD52, different allotypes of human IgG1 subclass were compared for their ability to activate human complement. In addition the roles of the different length hinge regions of IgG1 and IgG3 were investigated. It was found that the naturally occurring allotypes G1m(a,z) and G1m(f), and one artificially created isoallotype, G1m(null), did not significantly differ in their overall ability to cause cell lysis. However, some differences in binding of individual components of the classical activation pathway were detected. More of the complement component C1s seemed to be associated with the allotype G1m(f), although this did not result in an overall improvement in lytic potency. In this system the wild-type IgG3 was found to be less effective in complement lysis than IgG1. By shortening the hinge region of IgG3 to resemble that of an IgG1 antibody, increased complement binding was observed compared with that of wild-type IgG3 and the IgG1 allotypes. The overall lytic potency of the antibody was also improved compared with wild type IgG3 and it was also slightly more effective than the IgG1 allotypes.

Antigens, CD↗
PubMed1997

Versatile vectors for transient and stable expression of recombinant antibody molecules in mammalian cells.

We have developed new cassette expression vectors for the cloning of any intact V-region gene followed by any C-region gene. Both the heavy-and light chain vectors harbor a strong hCMV promoter, restriction site cassettes for cloning of both V- and C-region genes, transcription termination signals, fl-ori for single stranded DNA (ssDNA) synthesis, selection marker for Neomycin and SV40 ori for transient expression. The vectors accept VH and VL chain genes obtained by RT-PCR. Reamplification of the V genes is then performed with a new set of primers which are designed specifically for each individual V gene. Cloning into the vectors is aided by restriction sites located just outside the V-gene coding region, thus keeping the V-genes intact. The vectors also contain cloning sites for the exchange of genomic C-genes so that the resulting Ig genes may code for complete antibodies, antibody fragments or fusion proteins. A simple subcloning step permits the expression of both heavy and light chain genes from one single vector, thus avoiding co-transfection of the two vectors. The usefulness of the vectors was confirmed by construction of mouse-human chimeric antibodies. The V-genes were derived from a hybridoma cell line, TP-3, and was combined with human C kappa, C gamma 3 and C gamma 1 genes as well as with CH1 gamma 3. High yields of recombinant antibody products in NSO cells were obtained. Transient expression was also demonstrated.

Animals↗
PubMed1996

Effect of the IgM and IgA secretory tailpieces on polymerization and secretion of IgM and IgG.

Pentameric IgM and dimeric IgA both contain disulfide bonds between cysteines located in the secretory tailpieces of the heavy chains. To compare the influences of the mu and alpha tailpieces on the polymeric structure, we have replaced amino acids in the tailpiece of the human mu-chain with amino acids found in the corresponding positions in the human alpha tailpiece. We show that an IgM with an alpha tailpiece (IgM L561H, Y562V, L566V, S569A, D570E, T571V, and A572D) as well as IgM L561H, Y562V, and IgM A572D have a size distribution similar to that of wild-type IgM. However, one IgM mutant with a mu/alpha hybrid tailpiece (IgM L566V, S569A, D570E, T571V, and A572D) is secreted as a mixture of mainly hexamers, pentamers, tetramers, and dimers. The tetramers and dimers are specifically formed and secreted at the expense of pentamers and hexamers; no alterations in polymerization or secretion rates were observed. We have also incorporated the mu, alpha, and hybrid mu/alpha tailpieces to a human IgG3 or IgGL309C mutant. The IgG-tailpiece mutants are poorly secreted, but the secreted fractions contain multimeric molecules. Each of the mutants that contain both the L309C mutation and a secretory tailpiece forms mainly hexamers; however, small differences in polymer distribution exist for the different tailpieces. Comparison of the influence of different tailpieces on IgM and IgG polymeric structures suggests that the function of a specific tailpiece is dependent on other parts of the heavy chain, which can vary for different isotypes.

Amino Acid Sequence↗
PubMed1996

Abundant tyrosine residues in the antigen binding site in anti-osteosarcoma monoclonal antibodies TP-1 and TP-3: Application to radiolabeling.

The variable (V) genes of TP-1 and TP-3 MAbs have been cloned and sequenced. Because of the potential use of these antibodies in the diagnosis and treatment of osteosarcoma, it is important to determine the presence and position of amino acid residues that may react with radiolabeling within the V domains. In this article, location of the tyrosine residues is determined using the knowledge of immunoglobulin structures in general. The TP-1V domains have a total of 19 tyrosines, whereas TP-3V domains have 18, with approximately half of these located within complementarity determining regions (CDRs). Thus, if equal reactivity of all tyrosines is assumed, smaller fragments of MAbs have a high probability of being radiolabeled at one of these sites with possible resultant loss of antigen binding.

Amino Acid Sequence↗
PubMed1995

The structural requirements for complement activation by IgG: does it hinge on the hinge?

The flexibility of antibody molecules principally derives from the structure of the hinge region. It has generally been accepted that the flexibility of the IgG hinge is necessary for complement activation to occur; however, recent studies dispute this premise. As described here by Ole Henrik Brekke, Terje Michaelsen and Inger Sandlie, it now appears that the only requirement of the hinge region for complement activation is the presence of inter-heavy-chain disulfide bond(s). Furthermore, the structural basis for the differences between IgG subclasses with respect to effector functions appear to be located within the CH2 domain of the immunoglobulin molecule.

Amino Acid Sequence↗
PubMed1995

Cloning and sequencing of V genes from anti-osteosarcoma monoclonal antibodies TP-1 and TP-3: location of lysine residues and implications for radiolabeling.

Monoclonal antibodies TP-1 and TP-3 are of potential utility for the radioimmunodiagnosis of osteosarcoma in both human and canine patients. The V genes of these antibodies were cloned and sequenced and to facilitate radiolabeling of these proteins, the location of the lysine residues within these sequences have been determined. The V-domains of TP-1 contain a total of 12 lysines, 10 in the framework region and 2 in the CDR region, while the V-domains of TP-3 contain a total of 14 lysines, 11 in the framework region and 3 in the CDR regions. Using space-filling models, the availability of each lysine residue for radiolabeling, and potential interference with antigen binding was predicted.

Amino Acid Sequence↗
PubMed1994

One disulfide bond in front of the second heavy chain constant region is necessary and sufficient for effector functions of human IgG3 without a genetic hinge.

We have created four IgG3 mutants without a normal hinge region: (i) m0 without a genetic hinge; (ii) m0/C131S, where Cys-131 in m0 was mutated to Ser; (iii) m0/231C232 (formerly HM-1), where a Cys residue was inserted in m0 between Ala-231 and Pro-232; (iv) m0/C131S/231C232, which is a hybrid of m0/231C232 and m0/C131S. The wild-type IgG3 and all mutants bind 5-iodo-4-hydroxy-3-nitrophenacetyl groups. The wild type and mutants, m15 (with 15 aa in the hinge), m0/231C232, and m0/C131S/231C232, were all positive for complement-mediated lysis, antibody-dependent cellular cytotoxicity mediated by peripheral blood leukocytes, and phagocytosis by U937. m0/C131S/231C232 was only weakly positive and sometimes negative for respiratory burst activity mediated by peripheral blood neutrophils (polymorphonuclear leukocytes), whereas m15, m0/231C232, and wild-type IgG3 were strongly positive. The m0 and m0/C131S mutants were mainly negative for complement-mediated lysis, antibody-dependent cell-mediated cytotoxicity, and phagocytosis by U937 and polymorphonuclear leukocytes. The results indicate that a hinge spacer region is not necessary, but the correct alignment of the two second heavy chain constant regions in the IgG3 molecule by a minimum of one disulfide bond is necessary and sufficient for effector functions.

Amino Acid Sequence↗
PubMed1994

Human IgG isotype-specific amino acid residues affecting complement-mediated cell lysis and phagocytosis.

In this report we describe the construction of anti-5-iodo-4-hydroxy-3-nitrophenacetyl (NIP) mouse/human immunoglobulin (Ig) G4 chimeric molecules with altered amino acid residues in the CH2 domain. Three mutants are described. Gln-268 is substituted by His in gamma 4 Q268H, Ser-331 is substituted by Pro in gamma 4 S331P, and in gamma 4 Q268H/S331P both residues are substituted. The ability of the mutant molecules to induce complement-mediated cell lysis (CML) and phagocytosis by Fc gamma RII- and Fc gamma RIII-bearing polymorphonuclear leukocytes (PMN) were measured. In CML, gamma 4 Q268H was inactive, but both gamma 4 S331P and gamma 4 Q268H/S331P were active provided that the antigenic density on the target cells was high. In phagocytosis mediated by PMN, the mutants gamma 4 S331P and gamma 4 Q268H/S331P were both active only when complement was introduced. gamma 4 Q268H was not active in phagocytosis under any conditions. We conclude that His-268 in human IgG molecules does not modulate CML activity or phagocytosis mediated by Fc gamma RII and/or Fc gamma RIII. Pro-331 rescues CML activity in IgG4 molecules when the epitope density on the target cells is high, but does not affect Fc gamma RII/Fc gamma RIII-mediated phagocytosis. In this manner the mutants gamma 4 S331P and gamma 4 Q268H/S331P mimic human IgG2. This could indicate a structural similarity between IgG2 and these mutant molecules that distinguish them from both IgG1 and IgG3.

Animals↗
PubMed1993

Activation of complement by an IgG molecule without a genetic hinge.

The hinge region links the two Fab arms to the Fc portion of the IgG molecule. It mediates flexibility to the molecule and serves as a connecting structure between the two heavy chains. In addition it provides space between the Fab and Fc parts. All three properties have been proposed to be important for the ability of IgG to initiate complement activation leading to complement-mediated cell lysis (CML). Here we report the construction of a hinge-deleted mouse-human chimaeric IgG3 molecule with specificity for the hapten NIP (3-iodo-4-hydroxy-5-nitrophenacetyl), HM-1. HM-1 lacks the genetic hinge, but has an introduced cysteine between Ala 231 (EU numbering) and Pro 232 in the lower hinge encoded by the CH2 exon. The introduced cysteine forms a disulphide bond between the two heavy chains of the molecule. In CML, HM-1 shows a greater activity than IgG3 wild type. This is the first time an IgG molecule without a genetic hinge has been found to be active in CML. We conclude that the hinge functioning as a spacer is not a prerequisite for complement activation. Rather, its major role seems to be to connect the heavy chains to each other in the amino-terminal part of CH2. Because HM-1 is expected to have low Fab-Fc flexibility, this molecular feature is probably of no importance for complement activation.

Animals↗
PubMed1993

The extended hinge region of IgG3 is not required for high phagocytic capacity mediated by Fc gamma receptors, but the heavy chains must be disulfide bonded.

Fc gamma receptor (Fc gamma R) phagocytosis and respiratory burst were induced by chimeric mouse-human anti-(4-hydroxy-5-iodo-3-nitrophenyl) acetyl IgG3 antibodies with mutations in hinge and/or in CH1 region. IgG3 mutants with different hinge length ranging from 47 to 0 amino acids, an IgG3 molecule with an artificial hinge of just one cysteine residue (HM-1), and two hybrid IgG3 molecules with IgG4 hinge or IgG4 CH1-hinge were tested. Using the monocytic cell line U937 as effector cells, the mutated IgG3 molecules were very similar, revealing high activity, while the IgG3/IgG4 hybrids revealed a slightly reduced activity. However, the hingeless (0-h) mutant was negative, except after interferon-gamma stimulation when it became slightly positive. Interestingly, HM-1 was as active as the IgG3 mutants. With polymorphonuclear leucocytes (PMN) as effector cells we obtained some day-to-day variations, but all the IgG3 mutants were highly active, with the two shortest hinge mutants somewhat less active. The IgG3/IgG4 hybrid molecules revealed an intermediate activity, while IgG4 wild-type and the 0-h mutant were negative. However, the HM-1 molecule revealed an activity similar to that of the IgG3 mutants. The phagocytic activity of U937 was inhibited by monomeric IgG, indicating the importance of Fc gamma RI. In contrast, with PMN both blockage of Fc gamma RII and cleavage of Fc gamma RIII were required to significantly reduce the phagocytosis and respiratory burst, thus showing that both receptors contribute to the effect. These results demonstrate that the extended IgG3 hinge region is not necessary for a high phagocytic activity and that the major structural importance of the hinge is to connect the two heavy chains in this region.

Disulfides↗
PubMed1993

Human IgG3 can adopt the disulfide bond pattern characteristic for IgG1 without resembling it in complement mediated cell lysis.

In this paper we describe the construction of mouse-human IgG3 mutant antibodies resembling IgG1 in their disulfide bond pattern between the heavy and light chain (H-L) and between the two heavy chains (H-H). The effector functions of these mutant antibodies were compared to normal IgG3 and IgG1. Changing only the disulfide bond pattern between the heavy and light chains did not alter the ability to induce complement mediated cell lysis (CML), regardless of the amount of corresponding antigen that had been introduced to the surface of the target cells. However, alteration of the disulfide bond pattern between the two heavy chains had a large effect on CML due to shortening of the hinge from 62 to 15 amino acids. No difference between the mutants and normal antibodies in antibody-dependent cell-mediated cytotoxicity (ADCC) was observed. This suggests that IgG3 can adopt the H-L disulfide bond pattern of IgG1 without obtaining the CML activity characteristic for IgG1.

Amino Acid Sequence↗
PubMed1992

Antibody dependent cell-mediated cytotoxicity induced by chimeric mouse-human IgG subclasses and IgG3 antibodies with altered hinge region.

A matched set of chimeric mouse-human NP-antibodies were studied for the capacity to induce cell mediated cytotoxicity (ADCC) by normal peripheral blood NK/K cells. The target cells were sheep red blood cells (SRBC) sensitized with the haptens NP or NIP. All four IgG subclasses and several IgG3 variants with altered hinge were tested for ADCC activity. The hierarchy of the ADCC capacity among the subclasses was found to be IgG3 greater than IgG1 greater than IgG4 greater than IgG2. The superiority of IgG3 was only revealed at low effector cell:target cell ratio. The ADCC activity was for the most part unaltered by shortening the hinge region of IgG3 from 62 to 15 amino acids. Also, when the hinge region of IgG3 was mutated to become identical to that of IgG4, the ADCC activity was mainly unchanged. However, an IgG3 variant with deletion of all four hinge exons showed a depressed ADCC activity compared to the wild type. The IgG subclass pattern of complement-mediated lysis (CML) and ADCC is different and the capacity to induce CML and ADCC is changed differently by hinge region modification. Thus CML and ADCC have different structural requirements in the Fc region of IgG.

Amino Acid Sequence↗
PubMed1991

T-cell receptor tau delta +/CD3+4-8-T- cell acute lymphoblastic leukemias: a distinct subgroup of leukemias in children. A report of five cases.

In a 10-year study of T-cell acute lymphoblastic leukemias (T-ALL) in children, we have identified five cases expressing the T-cell receptor tau delta (TCR tau delta). The incidence (26%) of TCR tau delta+T-cell leukemias in our material was high. Clinically, the TCR tau delta+ leukemias represented a distinct subgroup of T-cell leukemias. Mean age at onset of disease, 1.8 years, was remarkably low for mature T-cell leukemias. White blood cell counts were high, lymph node enlargements were discrete, and no mediastinal tumors were seen. Four of five TCR tau delta+ leukemias carried rearrangements of the C tau 2 gene, and transcribed the T-early alpha genetic element.

Antigens, CD↗
PubMed1991

Chimeric mouse human IgG3 antibodies with an IgG4-like hinge region induce complement-mediated lysis more efficiently than IgG3 with normal hinge.

We have altered the amino acid sequence of the hinge and the first constant domain (CH1) of mouse/human chimeric IgG3 antibodies by site-directed mutagenesis, so as to make the sequences identical to those of IgG4. All the mutant antibodies with altered hinge region were more active in complement activation and complement-mediated lysis than native IgG3. The mutations in CH1, however, did not alter the activity. This demonstrates the importance of the hinge region in modulating this effector function. The results show that the primary structure of neither CH1 nor the hinge of IgG4 is responsible for the lack of complement activation shown by this subclass.

Amino Acid Sequence↗
PubMed1990

Enhancement of complement activation and cytolysis of human IgG3 by deletion of hinge exons.

The capacity to induce complement-mediated cell lysis is greatly enhanced by truncating the hinge of IgG3 through exon deletions. This was shown by establishing five new cell lines which secreted chimeric IgG3 molecules with specificity for the hapten 4-hydroxy-3-nitrophenacetyl (NP) and having 47,45,32,15, and 0 amino acid hinge regions (the wild-type IgG3 has 62 amino acids in the hinge). Efficient complement activation and complement-mediated cell lysis did not depend on a long total hinge or on a long 'upper' hinge (the stretch from the beginning of the hinge to the first inter-heavy chain S-S bond). On the contrary, the mutant having a 15 amino acid hinge element was up to 10 times more efficient in complement lysis than the wild type. Thus the complement-activation potential appeared to be down-regulated in the wild type. On the other hand, the mutant lacking the hinge altogether did not activate complement or induce complement-mediated cytolysis. These findings have to be taken into account when antibodies are designed for human therapy.

Antibody Affinity↗
PubMed1989

C1q binding to chimeric monoclonal IgG3 antibodies consisting of mouse variable regions and human constant regions with shortened hinge containing 15 to 47 amino acids.

We have constructed four different deletion mutants of a chimeric mouse-human IgG3 anti-(4-hydroxy-3-nitrophenyl)acetyl/(5-iodo-4 hydroxy-3 nitrophenyl) acetyl (NP/NIP) antibody lacking one or more of the four exons coding for the hinge region. The mutant variants all retained intact hinge region epitopes since they all reacted with IgG3 hinge-specific antibodies. Surprisingly, all the deletion mutants bound C1q equally well or even better than the wild type. Thus the high C1q binding activity of IgG3 compared to IgG1 is apparently not due to the total length of the IgG3 hinge, which is 62 amino acids, nor is it due to the length of the upper hinge which is the stretch from the end of CH1 to the first inter-heavy chain disulfide bond.

Amino Acid Sequence↗