Viral infection: A mildly elevated lymphocyte percentage can be a common response to viral infections, such as the common cold, influenza, or infectious mononucleosis, due to the body's immune response.

Stress or exercise: Physical stress or intense exercise can cause a temporary increase in lymphocyte count.
Smoking cessation: Quitting smoking can lead to an increase in lymphocyte percentage.
Vaccination: Recent vaccination can stimulate an immune response, resulting in a mild elevation of lymphocytes.

Lymphoma or leukemia: Although less likely, it is crucial to rule out hematological malignancies, such as lymphoma or leukemia, which can present with an elevated lymphocyte count.
HIV infection: Early stages of HIV infection can cause an increase in lymphocyte percentage, making it essential to consider this diagnosis, especially in high-risk individuals.
Tuberculosis: In some cases, tuberculosis can cause a mild elevation in lymphocyte count, particularly in the early stages of infection.

Lymphocytosis with autoimmune disorders: Certain autoimmune disorders, such as rheumatoid arthritis or lupus, can cause an elevation in lymphocyte count, although this is less common.
Primary immunodeficiency disorders: Rare genetic disorders affecting the immune system can lead to an elevated lymphocyte percentage.
Drug-induced lymphocytosis: Some medications, such as phenytoin or allopurinol, can cause an increase in lymphocyte count as a side effect.