<p>This study investigates the impact of minimal residual disease (MRD) on relapse in patients with acute myeloid leukemia (AML), focusing on its interaction with immune cells function. A total of 49 AML patients were enrolled in this prospective study and categorized into four groups: MRD⁻positive with relapse, MRD⁻positive without relapse, MRD⁻negative with relapse, and MRD⁻negative without relapse. Peripheral blood T lymphocyte subpopulations were analyzed using ten-color flow cytometry. CD4⁺ T cells were co-cultured with leukemia cell lines to assess the impact of CD4⁺ T cells on leukemia cell proliferation, apoptosis, and cytokine release. In MRD⁻positive patients, relapsed individuals exhibited significantly higher levels of CD4⁺ T cells, regulatory T (Treg) cells, and CD4⁺CD45RA⁺ naïve T cells compared to non-relapsed patients (<i>P</i> &lt; 0.0001,&#xa0;<i>P</i> = 0.0016, and&#xa0;<i>P</i> = 0.0066, respectively). Conversely, in MRD⁻negative patients, relapsed individuals showed a significantly lower percentage of Treg cells (<i>P</i> = 0.0068). Furthermore, we observed that CD4⁺ T cells were associated with enhanced leukemia cell proliferation and reduced apoptosis, along with markedly increased IL-10 expression. The available data raise the possibility that CD4⁺ T cell-derived IL-10 participates in immune microenvironment regulation, a process that may have implications for MRD maintenance and disease recurrence in AML.</p>