Kinetics of spleen and Peyer's patch lymphocyte populations during gut parasite clearing in Cryptosporidium parvum infected suckling mice

Data from experimental and human cryptosporidiosis have established a major role of specific immunity in the control of Cryptosporidium parvum infection. In this work, alterations in spleen and Peyer's patch (Pp) lymphocytes were investigated in the course of a spontaneously resolutive gut cryptosporidiosis in four-day-old suckling NMRI mice infected with either 4 × 10⁵ or 30 viable oocysts. Oocysts from entire small intestines, and spleen and Pp lymphocytes were examined using flow cytometry from day 7 to day 27 post-infection. Compared to uninfected animals, a 3–5 fold increase in the numbers of spleen TCR αβ+, CD4+, CD8+, TCR γδ+ and CD45R/B220+ lymphocytes was observed on day 17 post-infection in heavily infected animals. In Pp, more than ten-fold increases were observed, except for TCR γδ+ lymphocytes. At termination of infection, i.e. on days 21–23 after ingestion of 4 × 105 oocysts, T and B lymphocytes decreased rapidly in both organs, and remained lower than in uninfected animals on days 19–23 post-infection. In mice infected with 30 oocysts, similar alterations were observed in Pp, but not in spleen. Data suggest that in normally developing mice, clearance of gut C. parvum infection is associated with an initial increase in systemic and local lymphocyte numbers, followed by their decrease to below control levels during the recovery phase.