Alteration of in vitro anti‐tumor activity of tumor‐bearer sera by absorption with Staphylococcus aureus, cowan I

Low-speed centrifugation of retroviral vectors absorbed to a particulate substrate: a highly effective means of enhancing retroviral titre

“…This was speculated upon, and dismissed, as a problem in extracorporeal plasma immunoadsorption using heat-killed, fixed Staphylococcus aureus (Cowan I), 49 even so, only a modified procedure using the Fc binding protein A alone is licensed for humans (management of autoimmune thromobocytopenia purpura, ITPP). 50 Following promising results in virus-induced rat malignancy 51 extracorporeal adsorption of patient plasma using only protein A has reached the stage of clinical trials for metastatic breast cancer, 52,53 Kaposi's sarcoma 53 and colon carcinoma 53 on the basis of removal of antibody complexes thought to inhibit antitumour immune responses. 52,53 It is, however, tempting to speculate on the relative contributions of the protein A and fnb on Cowan I in treatment of other malignancies where evidence for the role of retrovirus is more compelling and reduction in viremia would be dependent upon circulating retroviral/antibody complexes.…”

Inhibition of mitogen-induced lymphocyte proliferation correlated to anticomplementary activity in sera from melanoma patients

“…However, in some preliminary studies, we found that in some sera from cancer patients that were both inhibitory and Ac, both activities could be removed by absorption with Staphylococcus aureus Cowan strain I. Since protein A from this bacterium absorbs immunoglobulin and can remove immune complexes inhibitory in other systems (Steel et al, 1974), it is possible that the protein A experiments indicate that the immune complexes themselves are the inhibitory factor. As suggested by Kilburn et al (1976), immune complexes might interact with other serum components that have inhibitory activity.…”

Ex vivo and in vivo Protein A Perfusion: Background, Basic Investigations, and First Clinical Experiences

“…Mechanisms of protein A perfusion which are possibly operative in tumor pa tients include: -reversal of immune suppression by re moving immunosuppressive factors by se lective binding to protein A [13,18]; -increase of natural killer cell activity, and of selective cellular cytotoxicity, all of which could be observed in a few patients only [20]; -decrease of Fc-receptor-binding activity of both circulating and splenic macrophages following protein A perfusion [34]; -induction of interferon and interleukin-2 production [35], and -a polyclonal activation of lymphocytes [35].…”

“…Protein A, which has been used for years in laboratories for adsorption and puri fication of IgG, has also been introduced as an adsorbent for therapeutic plasma frac tionation purposes. Several formats of ad sorption columns have been used: heatkilled formalin-fixed S. aureus Cowan I bac teria [13,14] or purified protein A attached to Sepharose® [15], collodion-charcoal [14] or silica [ 16], Protein A, a polypeptide with a molecular weight of 42,000 daltons has a binding affinity for human IgG subclasses 1, 2, and 4 but not for IgG3 [17,18]. Binding occurs in between the second and third con stant domain of the IgG heavy chains [17,19] [20,21] is in contrast to other reports, which could not confirm any immune-complex binding [16].…”