Methotrexate inhibited the production of malignant pleural effusion and regulated the tumor microenvironment of patients with advanced lung cancer,CD4+ T cells stimulated by methotrexate release more IL-2, while CD8+ T cells released less IFN-\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\gamma $$\end{document}γ32. Here, CD4 is linked to lung carcinoma.