Intracellular routing rather than cross-linking or rate of internalization determines the potency of immunotoxins directed against different epitopes of sIgD on murine B cells

May, Richard; Wheeler, H T; Finkelman, Fred D.; Uhr, Jonathan W.; Vitetta, Ellen S.

doi:10.1016/0008-8749(91)90292-j

Cited by 21 publications

(14 citation statements)

References 36 publications

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“…Neutralizing MAbs, which must prevent virus from entering uninfected cells, bind to well-characterized gp160 epitopes, including the CD4bs, gp120 V loops, and glycan, and gp41 MPER, whereas MAbs that make the best ITs, likely because they enhance internalization and intracellular routing to the endoplasmic reticulum, bind to the gp41 HR/loop region. In accord with the findings of previous studies (33,38), these results confirm that the ability of a MAb to make a potent IT is not a simple function of its binding to that cell. Indeed, internalization and appropriate intracellular routing are critical to the activity of an IT (33).…”

Section: Resultssupporting

confidence: 91%

“…In accord with the findings of previous studies (33,38), these results confirm that the ability of a MAb to make a potent IT is not a simple function of its binding to that cell. Indeed, internalization and appropriate intracellular routing are critical to the activity of an IT (33).…”

Section: Resultssupporting

confidence: 91%

“…As noted previously, ITs that bind to cells require internalization, specific pathways of intracellular routing, and release of the toxic moiety into the cytosol (13,33,35). In contrast, viral neutralization results from the ability of a MAb to block virus-receptor interactions, although other factors also come into play (3,28,29).…”

Section: Resultsmentioning

confidence: 90%

“…It has been established that for an IT to effectively kill a target cell, some portion of the IT-antigen must be internalized and routed to the endosome-Golgi apparatus (33). Those immune complexes that are routed to lysosomes do not make effective ITs, unless agents that disable lysosomal function are used (34).…”

Section: Resultsmentioning

confidence: 99%

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Identification of Human Anti-HIV gp160 Monoclonal Antibodies That Make Effective Immunotoxins

Pincus

Song

Maresh

et al. 2017

J Virol

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The envelope (Env) glycoprotein of HIV is the only intact viral protein expressed on the surface of both virions and infected cells. Env is the target of neutralizing antibodies (Abs) and has been the subject of intense study in efforts to produce HIV vaccines. Therapeutic anti-Env Abs can also exert antiviral effects via Fcmediated effector mechanisms or as cytotoxic immunoconjugates, such as immunotoxins (ITs). In the course of screening monoclonal antibodies (MAbs) for their ability to deliver cytotoxic agents to infected or Env-transfected cells, we noted disparities in their functional activities. Different MAbs showed diverse functions that did not correlate with each other. For example, MAbs against the external loop region of gp41 made the most effective ITs against infected cells but did not neutralize virus and bound only moderately to the same cells that they killed so effectively when they were used in ITs. There were also differences in IT-mediated killing among transfected and infected cell lines that were unrelated to the binding of the MAb to the target cells. Our studies of a well-characterized antigen demonstrate that MAbs against different epitopes have different functional activities and that the binding of one MAb can influence the interaction of other MAbs that bind elsewhere on the antigen. These results have implications for the use of MAbs and ITs to kill HIVinfected cells and eradicate persistent reservoirs of HIV infection.IMPORTANCE There is increased interest in using antibodies to treat and cure HIV infection. Antibodies can neutralize free virus and kill cells already carrying the virus. The virus envelope (Env) is the only HIV protein expressed on the surfaces of virions and infected cells. In this study, we examined a panel of human anti-Env antibodies for their ability to deliver cell-killing toxins to HIV-infected cells and to perform other antiviral functions. The ability of an antibody to make an effective immunotoxin could not be predicted from its other functional characteristics, such as its neutralizing activity. Anti-HIV immunotoxins could be used to eliminate virus reservoirs that persist despite effective antiretroviral therapy.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Identification of Human Anti-HIV gp160 Monoclonal Antibodies That Make Effective Immunotoxins

Pincus

Song

Maresh

et al. 2017

J Virol

Self Cite

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“…Since ITs are developed for treatment of cancer, the factors influencing the cytotoxic efficacy are studied extensively (36-42). Those factors include type of antigen and target cell, antigen density, IT binding affinity, and IT binding epitope, which eventually determines the number of IT internalized or intracellular route after internalization.…”

Section: Discussionmentioning

confidence: 99%

Differential Cellular Internalization of Anti-CD19 and -CD22 Immunotoxins Results in Different Cytotoxic Activity

et al. 2008

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B-cell malignancies routinely express surface antigens CD19 and CD22. Immunotoxins against both antigens have been evaluated, and the immunotoxins targeting CD22 are more active. To understand this disparity in cytotoxicity and guide the screening of therapeutic targets, we compared two immunotoxins, FMC63(Fv)-PE38-targeting CD19 and RFB4(Fv)-PE38 (BL22)-targeting CD22. Six lymphoma cell lines have 4-to 9-fold more binding sites per cell for CD19 than for CD22, but BL22 is 4-to 140-fold more active than FMC63(Fv)-PE38, although they have a similar cell binding affinity (Kd, f7 nmol/L). In 1 hour, large amounts of BL22 are internalized (2-to 3-fold more than the number of CD22 molecules on the cell surface), whereas only 5.2% to 16.6% of surface-bound FMC63(Fv)-PE38 is internalized. The intracellular reservoir of CD22 decreases greatly after immunotoxin internalization, indicating that it contributes to the uptake of BL22. Treatment of cells with cycloheximide does not reduce the internalization of BL22. Both internalized immunotoxins are located in the same vesicles. Our results show that the rapid internalization of large amounts of BL22 bound to CD22 makes CD22 a better therapeutic target than CD19 for immunotoxins and probably for other immunoconjugates that act inside cells. [Cancer Res 2008;68(15):6300-5]

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Quantitative analysis of protein synthesis inhibition and recovery in CRM107 immunotoxin-treated HeLa cells

Wenning

Yazdi

Murphy

1998

Biotechnol. Bioeng.

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Previously a mathematical model was proposed that quantitatively related protein synthesis inhibition kinetics of antitransferrin receptor–gelonin immunotoxins to the cellular trafficking of the targeting agent. That work is here extended to describe protein synthesis inhibition kinetics of immunotoxins containing the diphtheria toxin mutant CRM107. CRM107 differs from gelonin in both translocation and ribosomal inactivation mechanisms. Targeting agents used were antitransferrin monoclonal antibodies 5E9 and OKT9, OKT9Fab, and transferrin. CRM107 conjugates inhibited protein synthesis at substantially lower concentrations than gelonin conjugates; this effect was attributed to substantially higher translocation rates for CRM107. However, under certain conditions, CRM107 immunotoxin‐treated cells were able to recover completely; this behavior was never observed with gelonin immunotoxins. To quantitatively capture this phenomenon, extracellular and cytosolic degradation of the toxin as well as growth‐related recovery from toxin‐induced damage were incorporated into the mathematical model. Translocation and cytosolic degradation rate constants were determined for each immunotoxin. Unlike the gelonin conjugates, the translocation rate of CRM107 conjugates depended on the targeting molecule. This provided indirect evidence that CRM107 remains disulfide linked to the targeting agent for at least part of the translocation process. Although the CRM107 conjugates all had higher translocation rates and inhibited protein synthesis at lower concentrations than the gelonin conjugates, the cells' ability to recover from protein synthesis inhibition at low immunotoxin concentrations limits the utility of CRM107 conjugates for targeted cell killing. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 484‐496, 1998.

show abstract

Intracellular routing rather than cross-linking or rate of internalization determines the potency of immunotoxins directed against different epitopes of sIgD on murine B cells

Cited by 21 publications

References 36 publications

Identification of Human Anti-HIV gp160 Monoclonal Antibodies That Make Effective Immunotoxins

Identification of Human Anti-HIV gp160 Monoclonal Antibodies That Make Effective Immunotoxins

Differential Cellular Internalization of Anti-CD19 and -CD22 Immunotoxins Results in Different Cytotoxic Activity

Quantitative analysis of protein synthesis inhibition and recovery in CRM107 immunotoxin-treated HeLa cells

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