Natural killer cells normally kill cells that are infected with viruses. They do this by secreting a substance called perforin, which makes a hole in the cell membrane, and then injecting granzymes, which induce the cell to undergo apoptosis (programmed cell death). The CD8 cytotoxic T cells operate in the same way in terms of their killing mechanism.
Some years ago, Dr. Kevin Maher, who was in Dr. Nancy Klimas's group, reported that the natural killer cells in PWMEs are low in perforin. It was also found that the CD8 cytoxic T lymphocytes were also low in perforin. This would, of course, inhibit their cytotoxic activity.
I suggest that this new result is consistent with the mechanism I have proposed for low perforin in ME/CFS. It indicates that the NK cells and CD8 cells are "trying hard" to produce perforin by boosting the transcription of the PRF1 gene to messenger RNA, but the protein synthesis process is at least partially blocked and cannot respond. If glutathione is somewhat depleted in the NK cells and CD8 cells, the protein synthesis process would indeed be partially blocked.
I continue to propose, as I did in 2007, that other features of the observed immune dysfunction in ME/CFS can also be explained by the GD-MCB hypothesis. These include the shift to Th2 immune response, the elevated RNase-L and formation of the low-molecular-weight RNase-L, the elevated inflammation, the failure of lymphocytes to proliferate when stimulated with mitogens, the reactivation of viruses and intracellular bacteria, and the accumulation of pathogens over time.
So first, how does the immune system normally respond to viral infections? There are basically four types of responses, listed here in roughly the chronological order in which they normally occur:
1. Type I interferon (interferons alpha and beta) responses
2. Natural killer cell response
3. Virus-specific cytotoxic T lymphocyte (CD-8 "killer" T cell) response.
4. Antibody response
Type I interferons are secreted by infected cells, to alert nearby cells, and hopefully prevent them from becoming infected. The Interferon responses include the PKR, the 2,5-OAS RNase-L, and the Mx responses, among others. The PKR response inhibits the synthesis of viral proteins inside host cells. The 2,5-OAS RNase-L response degrades viral RNA inside host cells. The Mx response inhibits viral gene expression and assembly of the virions inside host cells.
The natural killer cells recognize virally infected cells in which the viruses are attempting to hide from the immune system by shutting off the Class I HLA mechanism that the CD-8 cells use to recognize virally infected cells. If the Class I HLA molecules are not displayed on the cell surface, the NK cell kills the cell.
The CD-8 killer T cells kill cells that are displaying viral antigens by means of the Class I HLA molecules.
Antibodies against viral antigens are made by B lymphocytes and plasma cells, and they bind to viruses that are outside the host cells, as when an infection is beginning or when viruses are spreading from one host cell to another.
This neutralizes the viruses, so that they cannot enter new host cells, and it can also "mark" them for attack by other cells of the immune system, such as macrophages.
O.K., now what happens to these responses in ME/CFS?
Well, the Type I interferon responses continue to work, and even though they are intended to be short term responses to hold back the viral infection until the "cavalry" in the form of the CD-8 killer cells arrives, and the CD-8 cells, together with the NK cells, knock out the viral infection, in ME/CFS the interferon responses continue to work overtime (and even become dysregulated in the case of the RNase-L) because the CD-8 killer cells are not able to take over. Sadly, the "cavalry" never arrives, leaving the "civilians" to battle the "Indians" in an ongoing guerrilla war.
What causes the formation of the dysregulated low-molecular-weight RNase-L molecules? I propose that glutathione depletion is responsible. It activates calpain, and calpain cleaves the normal RNase-L molecules. The cleaved parts join together, forming the unregulated LMW RNase-L.
Both the NK cells and the CD-8 killer T cells are rendered impotent by their inability to make perforin and granzymes in normal amounts. Furthermore, the CD-8 killer T cells are not able to multiply to outnumber the "bad guys" as they should. Why does this happen? I propose that it is a result of glutathione depletion and depletion of folates, respectively, which are part of the GD-MCB vicious circle mechanism that I believe is at the basis of the pathogenesis of ME/CFS.
Antibody production continues, and in fact may be increased, because of the shift toward the Th2 immune response in ME/CFS, which favors humoral immunity, i.e. the production of antibodies by B lymphocytes and plasma cells. What causes this shift? Again, I have proposed that glutathione depletion is responsible, in this case in the "naive" T cells.
So what we have are heightened interferon and antibody responses, but failure of the main "kill" mechanisms. The result is that latent viruses in the body (such as EBV, CMV and HHV6) are able to reactivate, and the immune system continues to fight with the weapons it has left, confining the viruses and keeping the host alive, but not winning the war against the viruses by completely knocking them out or putting them back into latency.
Now, what about your questions?
Would interferon treatment work? Well, to some degree, but without the other dysfunctional immune responses to help them, they cannot completely knock out the viruses.
Why don't PWMEs get colds and flus? I think it's because of the constantly elevated interferon responses. This produces what has been called the "antiviral state." With this going on, it's difficult for a newly introduced virus to get a foothold.
Does this have anything to do with the elevated cytokines in ME/CFS? Yes. The immune system is well aware that there are enemies inside the perimeter, and it is sounding the alarm, trying to organize the defense. The cells of the immune system are sending chemical messages back and forth to each other in the form of cytokines. However, because the NK cells and the CD-8 cells are impotent, even though the trumpet sounds, they don't respond, because they are not able to, so the messages just keep flying back and forth, unheeded.
So what's the solution to this problem? How do we win the war? Well, I'm still working on that, but I think that a big part of it will be to restore glutathione, folates and methylation, and that will probably require a methylation protocol.
Beyond that, because viruses that are well-entrenched have various ways of foiling the immune system, even though the immune system is restored, other measures will likely also be needed. One interesting one is GcMAF, which overcomes one of the strategies used by viruses to foil the immune system, i.e. nagalase. Antivirals are another possibility, especially in view of some success using them, as in Dr. Lerner's experience.
I hope this is helpful.
Best regards,
Rich