>Nope, people with severe CD4 deficiencies are actually very sick
What people learn in textbooks often is in contradiction with the facts. I have been working with AIDS patients since AIDS appeared. We used to see people all the time with zero to near zero CD4 counts that showed no ill effects. Why? Because there are numerous components to the immune system, and CD4s do not govern all of them. The immune system is comprised of various white blood cells, various cytokines (some of which are also generated by B cells), antibodies, monokines, peroxide, SOD, adrenal steroids, the intestinal flora, etc. To think that CD4s are going to govern the immune system is like saying that removing one kidney is going to kill the person because they will no longer be able to remove water and waste. IN such as case the other kidney will enlarge and the body will continue to remove water and waste through sweating, stool, the other kidney, etc. The body has redundancies built in just in case one system fails.
"CD8+ T cells can respond to antigen in the absence of CD4+ T cell help (21, 37–40)."
"Our data support the previous studies showing that CD8 cells can generate a strong response in the absence of CD4+ T cells, but we have determined that the CD4 molecule is required for this to occur optimally."
The cells do not have to function optimally to do their job well enough. Just like our stomachs do not produce optimal levels of stomach acid as we age, but we do not starve to death from it. Just because CD4s are destroyed this does not mean the immune system collapses. And HIV does not collapse the immune system. In fact many AIDS patients, around 30%, have been found to be HIV free. Apparently there is something else causing the immune collapse. Unfortunately they have not looked beyond HIV because too many ignorant scientists still falsely believe presence of means cause of.