Fig 4.

HTLV-1- and HTLV-2-induced immortalization of CD4⁺ and CD8⁺ T cells. Gamma-irradiated 729Achneo cells (wtHTLV-1) and 729pH6neo cells (wtHTLV-2) were cocultured with freshly isolated uninfected PBMCs for 9 weeks. The cultures were harvested, stained with anti-CD3, anti-CD4, and anti-CD8 antibodies, and analyzed by flow cytometry once every week. The percentages of CD4⁺ and CD8⁺ T cells within the CD3⁺ T cell gate were determined and normalized to 100. The normalized CD4⁺ T cells in the individual wells for both the viruses are plotted. Each well is represented by the corresponding symbol, for which the left y axis shows the percentage of CD4⁺ T cells and the right y axis shows the percentage of CD8⁺ T cells. (A) Longitudinal analysis of the T cell phenotype of wtHTLV-1- or wtHTLV-2-induced immortalization. Eight wells were analyzed at each time point for both viruses. The circles represent wtHTLV-1, and the triangles represent wtHTLV-2. The vertical bar represents the 95% confidence interval for each of the viruses at the given time points. The trend lines connect the estimated mean values in each of the two groups, which is an adjusted mean value from a generalized linear model. The differences in the mean values between wtHTLV-1 and wtHTLV-2 were statistically significant from week 4 onwards (week 4, P = 0.04; weeks 5 to 9, P < 0.001; generalized linear model with Tukey's method for multiplicity adjustment). (B) T cell phenotypic analysis of wtHTLV-1- or wtHTLV-2-induced immortalization after 9 weeks of coculture (remaining wells from data above). The bar represents the average percentage of T cells. The total number of wells analyzed and the average percentages (standard deviations [SD]) for both CD4⁺ and CD8⁺ T cells are indicated below. The percentage of wtHTLV-1-immortalized CD4⁺ T cells was significantly higher than that of the wtHTLV-2-immortalized CD4⁺ T cells (P < 0.001, t test).