Samenvatting

Cyclophosphamide (CPA) is a commonly used alkylating chemotherapeutic drug that targets rapidly dividing cells causing apoptosis by crosslinking DNA. While effective against neoplasms, CPA can also affect healthy immune cells. This study investigated whether a single dose of CPA alters healthy lymphoid and non-lymphoid tissue and cells in rats. Six rats were used, including untreated controls and CPA-treated animals receiving a one-time intraperitoneal dose of 12 mg CPA dissolved in 0.6 ml saline. Lung, liver, kidney, thymus, and spleen tissues were collected and analysed using HE-staining and IHC to assess B-lymphocytes, T-lymphocytes, and macrophages. Non-lymphoid organs showed no macroscopic or microscopic changes at any time point, confirming CPA has no effect in these tissues. In contrast, the lymphoid organs showed drastic changes. The thymus showed pronounced cortical depletion on day 4, followed by renewed thymocyte influx on day 8. Correspondingly, macrophage numbers increased on day 4 and decreased on day 8. In the spleen, both B and T lymphocyte populations declined at days 4 and 8. Particularly within the marginal zone and periarteriolar lymphoid sheaths, with limited recovery observed on day 8. Splenic macrophages increased over time, likely to clear apoptotic debris. These findings demonstrate that a single CPA dose selectively disrupts lymphoid tissues while sparing non-lymphoid organs, with faster recovery observed in the thymus than in the spleen.