Twenty-one multiparous and two primiparous Holstein cows were grouped according to infection status with Mycobacterium avium subsp. paratuberculosis (MAP), the causative microorganism for Johne’s disease (JD). The effect of parturition and infection on the percentages of CD4 + , CD8 + , and T-cells, B-cells, and monocytes in the peripheral blood were monitored. The data suggest that changes in the percentages of lymphocyte subsets and monocytes are modulated by both infection status and the periparturient period.