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Preparation of Interferons
All of the interferons offered by Global Water & Biology, Conservation Research Institute & Access Biomedical are produced from nonrecombinant animal cell cultures using proprietary methods for cell growth, induction, accumulation, purification and lyophilization of the materials. The interferons are induced by exposing high- density cell cultures to the Manhattan (Kansas) strain of Newcastle disease virus, most of which is removed at the conclusion of induction. Interferons are accumulated in medium which contains no exogenous protein. During the accumulation phase, a gross protein concentration of 30 to 100 g/mL appears in the extracellular medium, consisting primarily of noninterferon proteins secreted by the cultures during accumulation of interferon as well as trace amounts of bovine serum proteins remnant from the growth phase and chick chorioallantoic fluid and Newcastle disease virus proteins arising from the induction phase. The titers of the crude interferons as removed from induced cell cultures are generally of the order of (approx.)10^5 IU per mL (human, rabbit and rat) to >10^6 IU/mL (mouse), and therefore the specific activities of the crude materials are usually in the range 10^6 to 5 x 10^7 IU/mg.
Designations of Interferons
The mouse and human interferon activities are designated as alpha or beta based upon: (1) distinct properties in a variety of chromatographic systems including controlled- pore glass, blue sepharose, hydroxylapatite, gel filtration and immunoaffinity columns; (2) distinct electrophoretic mobilities in discontinuous SDS- PAGE which confirm published reports; (3) distinct patterns of inactivation, stabilization or renaturation of activity by a variety of detergents, mercaptoethanol and heat; (4) distinct patterns of cross- reactivity when assayed with heterospecific cell cultures; and (5) results of neutralization by specific antisera or immunoglobulins in checkerboard titrations. More information is given on p. 22. The designations of mouse and human interferons as alpha or beta have been verified extensively in other laboratories. In particular, the mouse alpha, beta and alpha + beta interferon reference reagents distributed beginning in 1988 by the NIH (U.S.) and NIBSC (U.K.) have been prepared from interferons provided by Access Biomedical which are identical to lots listed herein, and whose designations as alpha, beta or the unfractionated mixture have been verified rigorously in other laboratories in connection with their adoption as international reference reagents (see p. 23).
The interferon nomenclature based upon Greek letters [Nature, 286:110 (1980)] has caused some confusion concerning analogy between the mouse and human systems. For mouse interferons the terms fibroblast and leukocyte interferon have no meaning comparable to that for human interferons and the designations alpha and beta refer, respectively, to the antigenically distinct, lower- and higher- molecular weight components, both of which are reportedly synthesized by all mouse cells. For human interferons the designations alpha and beta correspond to the antigenically distinct species previously designated as leukocyte and fibroblast interferons, respectively; however, these are misnomers since fibroblasts can synthesize alpha, and lymphoblasts can synthesize beta, interferons. In both species gamma refers to the acid- labile ("immune" or "type II") interferons whereas the alpha and beta interferons of both species which are included in this catalog are acid- stable ("classical" or "type I"). The rabbit and rat interferons supplied by Access Biomedical are clearly of the acid- stable type but have not been characterized further as regards alpha or beta components (please see also pp. 24- 25).
Acid- labile human alpha interferons have been prepared from time to time and are available on special order.
Access Biomedical currently does not offer gamma interferons of any animal species. However, a highly purified monoclonal rat immunoglobulin G1 which neutralizes mouse gamma interferon is available (please see p. 18).
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