Low polys means low neutrophils, and high lymphs indicate high lymphocytes, according to WebMD. Neutrophils and lymphocytes are both types of white blood cells. The National Institute of Health says that a combination of low neutrophils and high lymphocytes could be caused by a viral infection, such as the measles.
Neutrophils protect against bacteria, and low levels of neutrophils may mean more risk of infection, states WebMD. Lymphocytes are broken down into two groups, B cells and T cells. B cells are made in the lymphatic system and in the bone marrow, whereas T cells are produced in the thymus, explains the Partnership for Environmental Education and Rural Health.