Antibody synthesis genes

Glucocorticoids inhibit acquired or cell-mediated immunity. Their effects are mediated via inhibition of genes that code for various cytokines. The cytokines inhibited by glucocorticoids include IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8 and IFN-y. IL-2 inhibition by corticosteroids is the most crucial effect in immunosuppression, which results in the inhibition of T-cell proliferation and activation of cytolytic T cells. Glucocorticoids also slightly affect humoral immunity by inhibiting B-cell clonal expansion and antibody synthesis, and these effects are mediated via their ability to inhibit B cells ability to express IL-2 and IL-2 receptors. 

The Federal investment in R D infrastructure outlined above made possible the fundamental knowledge and techniques upon which current drug discovery depends. The advances in molecular biology, which form the core of biotechnology (445), include recombinant DNA processes, monoclinal antibodies, and gene synthesis and splicing. Chapter 5 discusses the importance of these techniques in today s pharmaceutical R D process. These advances were made, for the most part, in university laboratories and relied heavily on Federal support. 

In differentiation of one antibody-forming clone of cells, a gene rearrangement links one of the approximately 300 V sequences with one of the 4 J sequences. All of the DNA that lies between these two spliced sequences is deleted in this rearrangement and disappears from all progeny of this cell line. Any upstream V sequences (on the 5 side, to the left in Figure 25.32) and downstream J sequences (on the 3 side, to the right) remain in these cells but are not used in antibody synthesis. 

It is remarkable that Selections I and II give results so similar despite the different origin of their foundation populations. This similarity suggests that the frequency of the genes involved in antibody synthesis is comparable in the two foundation populations of outbred albino mice. 

These experiments demonstrate that the group of genes governing antibody synthesis regulates the production of antibody molecules belonging to the two main classes of Ig. The study of the antibody response to other protein antigens hen egg albumin, BSA and DNP-BGG have confirmed the preceding conclusion and extended these results to the other classes and sub-classes of antibody previously mentioned. 

Product formation kinetics in mammalian cells has been studied extensively for hybridomas. Most monoclonal antibodies are produced at an enhanced rate during the Gq phase of the cell cycle (8—10). A model for antibody production based on this cell cycle dependence and traditional Monod kinetics for cell growth has been proposed (11). However, it is not clear if this cell cycle dependence carries over to recombinant CHO cells. In fact it has been reported that dihydrofolate reductase, the gene for which is co-amplified with the gene for the recombinant protein in CHO cells, synthesis is associated with the S phase of the cell cycle (12). Hence it is possible that the product formation kinetics in recombinant CHO cells is different from that of hybridomas. 

Cytokines. Figure 1 Inhibition of cytokine synthesis during activation of the specific immune system. The monoclonal antibodies Muromonab and Basiliximab are specific for the CD3 complex of the T-cell receptor, and for the IL-2 receptor on lymphocytes, respectively. Cyclosporin and Tacrolimus inhibit activation of cytoplasmic NF-AT, a transcription factor essential for activation of the IL-2 gene ( NFAT Family of Transcription Factors). Sirolimus interferes with mTOR signaling and inhibits IL-2 dependent proliferation. Red pharmaka, blue target proteins. 

Figure 36-4. Illustration of the tight correlation between the presence of RNA polymerase II and RNA synthesis. A number of genes are activated when Chirono-mus tentans larvae are subjected to heat shock (39 °C for 30 minutes). A Distribution of RNA polymerase II (also called type B) in isolated chromosome IV from the salivary gland (at arrows). The enzyme was detected by immunofluorescence using an antibody directed against the polymerase. The 5C and BR3 are specific bands of chromosome IV, and the arrows indicate puffs. B Autoradiogram of a chromosome IV that was incubated in H-uridine to label the RNA. Note the correspondence of the immunofluorescence and presence of the radioactive RNA (black dots). Bar = 7 pm. (Reproduced, with permission, from Sass H RNA polymerase B in polytene chromosomes. Cell 1982 28 274. Copyright 1982 by the Massachusetts Institute of Technology.)...

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