In non-neoplastic mucosa adjacent to gastric cancer (Figure 5; Table 2 and Table 3), CVID patients harboured higher PD-L1+ intraepithelial lymphocytes (p = 0.038), while CD20+ intraepithelial lymphocytes were lower in number (p = 0.001); the lamina propria of CVID patients showed an enrichment of Foxp3+, GATA3, CD4+ and CD8+ lymphocytes (p = 0.001; p = 0.023; p = 0.001; p = 0.007), and there was the expected paucity of plasma cells (p < 0.001). This evidence concerns the gene CD4 and common variable immunodeficiency.