Post‐transcriptional regulation of interferon‐alpha 4 subtype production by lymphoblastoid cells

Abstract

The constitutive production of interferon-alpha (IFN-alpha) subtypes by the lymphoblastoid cell lines, Namalwa, Daudi and Raji, was investigated using sensitive and semi-quantitative flow cytometric techniques. Further, we sought to determine whether the previously described failure of these cell lines to produce IFN-alpha-4 was a result of the deletion of the IFN A4 gene. Cytoplasmic production of IFN-alpha-2 and IFN-alpha-4 was assessed using IFN-alpha subtype-specific antipeptide antibodies and FITC-labelled secondary antibodies in indirect immunofluorescence-flow cytometry studies. The constitutive production of IFN-alpha-2 was detected in all three cell lines. Significant increases in fluorescence representing increased production of IFN-alpha-2 and possibly other IFN-alpha subtypes were detected after induction by Sendai virus. Approximately 100 per cent of cells in the Namalwa, Daudi and Raji cell populations contained IFN-alpha-2 before and after induction. However, no cells from the same cell populations contained the IFN-alpha-4 subtype. Analysis of genomic DNA isolated from the lymphoblastoid cells using the Polymerase Chain Reaction (PCR) and oligonucleotide primers specific for IFN A2 or IFN A4 confirmed the presence of the genes encoding both IFN-alpha subtypes. Furthermore, using reverse transcriptase-PCR amplification, mRNAs for both IFN-alpha-2 and IFN-alpha-4 were detected. Therefore, in contrast to some leukaemias and derived cell lines where IFN A genes have been deleted, these cell lines of B cell lineage exhibit selective expression of IFN A genes, as a result of altered transcriptional/translational control of IFN-alpha expression.

CD8+ Lymphocytes from Healthy Blood Donors Secrete Antiviral Levels of Interferon-Alpha

“…It has previously been reported that various lymphoblastic T cell lines, including the CD3+CD8+TCRα/β+ HPB-ALL cell line, can secrete appreciable levels of IFNα and IFNβ [40,41]. In addition, by immunofluorescent microscopy, it has been shown that nearly all primary T cells from healthy blood donors constitutively express intracellular IFNα [42]. The present discovery was facilitated by our novel cell culture procedure that derives CD8+ T cell culture supernatants from serumfree medium (Figure 1).…”

Alpha/beta interferons increase host resistance to murine AIDS

“…Alternatively, samples may have contained only IFN mRNA which had not been translated into protein at the time of sampling and bioassay (i.e., there may be posttranscriptional control of IFN-␣/␤ expression). Detection of IFN-␣/␤ mRNA by RT-PCR in the absence of detectable bioactivity of the protein has been reported previously (11). IFNs present at levels below the detection limits of the bioassay may act in a paracrine manner in critical target organs, being rapidly taken up by nearby cells such that whole-organ homogenates contain little bioactive material.…”

“…It is noteworthy that some IFNA mRNA was present in both liver and spleen samples from uninfected, resistant mice. This suggests that these mice have a highly sensitive IFN response that is reminiscent of the constitutive, low-level IFN production seen in some human cells (11). Such low constitutive levels may also act to prime a stronger response to viral stimulation.…”

The Production and characterization of Polyclonal Antibodies Against Interferon Alpha in Mice

“…Although animal models have been used for the production of polyclonal antibodies [5], the current study used a slightly different method as it focused on producing antibodies specifically against IFN-Alfa in an animal model. On the contrary, most of the previous researches focused on the production of polyclonal antibodies against IFN-Alfa in cell cultures and human peripheral blood cultures [22,23].…”