The capacity of protein aggregates to enhance immune responses to the monomeric form of the protein has been known for over a half-century. Despite the clear connection between protein aggregates and antibody mediated adverse events in treatment with early therapeutic protein products such as intravenous immune globulin (IVIG) and human growth hormone, surprisingly little is known about the nature of the aggregate species responsible for such effects. This review focuses on a framework for understanding how aggregate species potentially interact with the immune system to enhance immune responses, garnered from basic immunologic research. Thus, protein antigens presented in a highly arrayed structure, such as might be found in large nondenatured aggregate species, are highly potent in inducing antibody responses even in the absence of T-cell help. Their potency may relate to the ability of multivalent protein species to extensively cross-link B-cell receptor, which (1) activates B cells via Bt kinases to proliferate, and (2) targets protein to class II major histocompatability complex (MHC)-loading compartments, efficiently eliciting T-cell help for antibody responses. The review further focuses on protein aggregates as they affect an immunogenicity risk assessment, the use of animal models and studies in uncovering effects of protein aggregates, and changes in product manufacture and packaging that may affect generation of protein aggregates.

/pdf/effects-of-protein-aggregates-an-immunologic-perspective-3so336i4gv.pdf

Effects of protein aggregates: an immunologic perspective.

The purpose of this study was to evaluate human umbilical cord blood as an alternative to bone marrow in the provision of transplantable stem/progenitor cells for hematopoietic reconstitution Although no direct quantitative assay for human hematopoietic repopulating cells is at present available, the granulocyte-macrophage progenitor cell (CFU-GM) assay has been used with success as a valid indicator of engrafting capability We examined greater than 100 collections of human umbilical cord blood for their content of nucleated cells and granulocyte-macrophage, erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells, in many cases both before and after cryopreservation First it was determined that granulocyte-macrophage, erythroid, and multipotential progenitor cells remained functionally viable in cord blood untreated except for addition of anticoagulant for at least 3 days at 4 degrees C or 25 degrees C (room temperature), though not at 37 degrees C, implying that these cells could be satisfactorily studied and used or cryopreserved for therapy after transport of cord blood by overnight air freight carriage from a remote obstetrical service Granulocyte-macrophage progenitor cells from cord blood so received responded normally to stimulation by purified recombinant preparations of granulocyte-macrophage, granulocyte, and macrophage colony-stimulating factors and interleukin 3 The salient finding, based on analysis of 101 cord blood collections, is that the numbers of progenitor cells present in the low-density (less than 1077 gm/ml) fraction after Ficoll/Hypaque separation typically fell within the range that has been reported for successful engraftment by bone marrow cells Another observation of practical importance is that procedures to remove erythrocytes or granulocytes prior to freezing, and washing of thawed cells before plating, entailed large losses of progenitor cells, the yield of unwashed progenitor cells from unfractionated cord blood being many times greater The provisional inference is that human umbilical cord blood from a single individual is typically a sufficient source of cells for autologous (syngeneic) and for major histocompatibility complex-matched allogeneic hematopoietic reconstitution

https://www.pnas.org/content/pnas/86/10/3828.full.pdf

Human umbilical cord blood as a potential source of transplantable hematopoietic stem/progenitor cells

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.1840360704

Course and outcome of hepatitis C.

Background Some epidemiologic studies suggest a link between hepatitis C virus (HCV) infection and some B-cell non-Hodgkin's lymphomas. We undertook this study after a patient with splenic lymphoma with villous lymphocytes had a hematologic response after antiviral treatment of HCV infection. Methods Nine patients who had splenic lymphoma with villous lymphocytes and HCV infection were treated with interferon alfa-2b (3 million IU three times per week) alone or in combination with ribavirin (1000 to 1200 mg per day). The outcomes were compared with those of six similarly treated patients with splenic lymphoma with villous lymphocytes who tested negative for HCV infection. Results Of the nine patients with HCV infection who received interferon alfa, seven had a complete remission after the loss of detectable HCV RNA. The other two patients had a partial and a complete remission after the addition of ribavirin and the loss of detectable HCV RNA. One patient had a relapse when the HCV RNA load again became d...

https://www.nejm.org/doi/pdf/10.1056/NEJMoa013376

Regression of Splenic Lymphoma with Villous Lymphocytes after Treatment of Hepatitis C Virus Infection

The expiry of the first patents for recombinant-DNA-derived biopharmaceuticals will open the possibility of marketing generics, if they can be shown to be essentially similar to the innovator product. However, as shown by the problem of immunogenicity, the properties of biopharmaceuticals are dependent on many factors, including downstream processing and formulation. Products from different sources cannot be assumed to be bioequivalent, even if identical genes are expressed in the same host cells and similar production methods are used. Some of the influencing factors are still unknown, which makes it impossible to completely predict biological behaviour, such as immunogenicity, which can sometimes lead to serious side effects.

Bioequivalence and the immunogenicity of biopharmaceuticals

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.510270433

Quantification of the initial decline of serum hepatitis c virus RNA and response to interferon alfa

Interleukin-2 (IL-2) is a 15 kDa glycoprotein with proven activity as an immune stimulant in the treatment of malignant disorders, congenital and acquired immune deficiencies, infectious disorders, and as an adjuvant to vaccines Both natural and recombinant type IL-2 preparations have been applied in clinical treatment trials and have turned out to be immunogenic, although to a varying extent Enzyme immunoassays and western blotting are standard procedures for the detection of IL-2-binding antibodies, whereas the neutralizing capacity of these antibodies is frequently demonstrated by inhibition of IL-2-dependent cell growth in vitro The rate of treatment-induced IL-2 antibodies has varied from 0% to 100% in reported trials and frequently exceeded 50% in patients exposed to recombinant IL-2, whereas natural type IL-2 appeared to be little immunogenic Duration of treatment, cumulative IL-2 dose, and route of IL-2 administration are likely to determine both the rate of seroconversion as well as composition and properties of the anti-IL-2 antibodies Interleukin-2 antibodies are polyclonal in nature and predominantly composed of IgM and IgG types Frequently they react with both recombinant and natural IL-2 types As a rule, neutralizing IL-2 antibodies are detected in serum samples with high IL-2-binding titers and are recognized later than their non-neutralizing predecessors Neutralization in vitro, however, does not predict neutralization in vivo, and there are very rare patients with documented, antibody-mediated loss of response to IL-2 treatment More frequently, IL-2 antibodies will limit the expression of IL-2-dependent proteins in vivo, but the opposite has also been observed Although the precise mechanism of antibody induction by IL-2 is unknown, immunogenicity of some drug formulations rather than polyclonal B-cell activation appears to play a critical role Approaches aiming at limiting the immunogenicity of IL-2 preparations are discussed, and strategies how to recognize and circumvent antibody-mediated IL-2 resistance are presented

Treatment-induced antibodies to interleukin-2

BACKGROUND Prolonged therapy with interferon (IFN) may lead to the formation of IFN antibodies. METHODS Patients with renal cell carcinoma (n = 270) with advanced localized disease were randomized after complete tumor resection to receive treatment with adjuvant recombinant IFN-alpha-2a (rIFN-alpha 2a) (9 x 10(6) IU subcutaneously, three times per week for a maximum of 12 months) versus no treatment. Patients (IFN-treated group, 106 patients; control group, 97 patients) were monitored for the presence of rIFN-alpha 2a antibodies. RESULTS Of 86 IFN-treated patients observed for more than 2 months, 40 (47%) had IFN-alpha 2a-binding and 25 (29%) had IFN-alpha 2a-neutralizing antibodies developed within a median of 3 and 6 months, respectively. A distinct peak in binding antibody titers occurred at 6-9 months. Therapy-induced neutralizing antibodies were equally reactive with two other recombinant IFN-alpha-2 subtypes but poorly recognized natural IFN-alpha (IFN-alpha), recombinant IFN-alpha-1/alpha-8, and recombinant IFN-omega-1. The duration of remission and rate of relapse were independent of the antibody status, although neutralizing and most non-neutralizing antibodies correlated with a reduction in the IFN-induced increase in beta-2-microglobulin levels. CONCLUSIONS Patients treated with IFN-alpha 2a should be monitored for the presence and clinical relevance of IFN-alpha antibodies to determine those who could respond to alternative treatment.

Interferon‐alpha antibodies in patients with renal cell carcinoma treated with recombinant interferon‐alpha‐2A in an adjuvant multicenter trial

A-52-year-old patient presented with a 2-year history of multiple myeloma, recurrent episodes of hypercalcemia, and extensive bone involvement. She developed pulmonary infiltrates, initially misdiagnosed as interstitial pneumonia. High-resolution computed tomography and bone scintiscanning indicated pulmonary calcification, which was confirmed by a transbronchial biopsy. Cytostatic treatment of multiple myeloma in combination with repetitive i.v. administration of bis-phosphonates over a period of 6 months led to a significant improvement of clinical symptoms. Regression of pulmonary infiltrates was demonstrated by chest radiograph and computed tomography. There are only a few reports on pulmonary calcification in patients with multiple myeloma; the condition was associated mostly with progressive disease, kidney failure, adult respiratory distress syndrome and bad prognosis. In our patient isolated calcification of the lungs without involvement of other organ systems was successfully treated. These findings suggest that interstitial pulmonary calcinosis in multiple myeloma can be reversed by normalization of serum calcium levels using bisphosphonates combined with cytostatic treatment.

Reversible metastatic pulmonary calcification in a patient with multiple myeloma.

We report a case of a patient with systemic mastocytosis who was treated with interferon-gamma. Because of severe diarrhoea, nausea and weight loss due to mast cell infiltration of the gastric mucosa the patient received 150 micrograms d-1 interferon-gamma subcutaneously for 10 months. During therapy, the plasma concentrations of IL-3, IL-4 and GM-CSF, which seem to play a role in mast cell growth and differentiation were monitored. The patient had good symptomatic relief and the initially very high eosinophil counts in the peripheral blood showed a partial reduction. However, after 4 months of therapy the patient relapsed. In serum obtained after the relapse, but not in stored serum from the beginning of the therapy, neutralizing antibodies against interferon-gamma were found. Therefore an initial response to the therapy and a secondary failure mediated by treatment-induced antibodies against recombinant interferon-gamma might be suggested. Interferon-gamma may be a well tolerated therapeutic option in systemic mastocytosis. However, treatment-induced neutralizing antibodies against recombinant interferon-gamma should be considered if secondary treatment failure occurs.

Treatment of systemic mastocytosis with interferon-γ : failure after appearance of anti-IFN-γ antibodies

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