The lymphocytes (a type of white blood cell), are responsible for fighting bacteria in our bodies, so when these are low, it means that we will get sick more easily as our body is less able to fight illness.
If you have been diagnosed with this problem, I assume your doctor has told you the cause. Sometimes it is just that we don't produce enough lymphocytes, or possibly that they are being destroyed or trapped in the lymph nodes or spleen.
A low lymphocyte count can also be hereditary or can occur as part of a disease or illness. Often, there are no symptoms as such with a low lymphocyte count, so it is usually found when the patient presents with another illness.
In this case the doctor with treat the actual disease or illness which, hopefully, will restore the correct balance of the lymphocyte cell count.
If the cause is hereditary, a blood stem cell transplant or bone marrow transplant may be required. However, scientists are working on medicines to help the body to make more lymphocyte cells, so hopefully transplants will be a thing of the past in the near future.