Purified lymphocytes derived from the spleen of 15 infected and nine non-infected rats proliferated in response to stimulation with 0.5 μg of OM fractions of Leptospira. Both infected and control animals showed a statistically significant (p < 0.001) increase in percentage of proliferating B cells (CD3−, B220+, or CD19+) and T cells (CD3+) when cultured in the presence of Leptospira OM fraction compared to lymphocytes cultured with media alone (No Stim), Figures 3A,B. The gene discussed is CD19; the disease is ocular melanoma.