Introduction: The histologic features of H. pylori (HP) - associated gastritis, gastric and duodenal ulcers include a mixed inflammatory infiltrate of polymorphonuclear leukocytes, plasma cells and T-cells. The role and association of macrophage infiltration has not been studied.

Objective: We sought to determine if there was a difference in the number of macrophages in the lamina propria of gastric biopsies in HP infected children, patients with other gastritides and children with normal gastric mucosa.

Methods: Macrophage infiltration in gastric biopsies of 12 individuals with HP-associated gastritis and a similar number of other gastritides were assessed by using brightfield microscopy and compared to an equal number of normal biopsies. Absolute and mean number of macrophages were counted and recorded per 10 high power fields. Macrophages were identified morphologically, on H&E stained slides, and immunocytochemically, using antibodies to two different macrophage markers, HAM 56 and CD 68.

Results: An increased number of macrophages in the HP infected patients was identified by H&E stain when compared to other gastritides and normals (mean = 2.6 vs 1.3 vs 0.3 per HPF). Similar findings were observed using the HAM 56 stain (mean = 5.7 vs 2.7 vs 0.5 per HPF). The CD 68 stain demonstrated an increased mean macrophage number in HP infected individuals and other gastritides when compared to normals (mean = 7.3 vs 7.2 vs 4.0 per HPF).

Conclusion: Preliminary data suggests that there is an increased number of macrophages in HP infected individuals and non-HP associated gastritides when compared to normals. The macrophage appears to play a role in the inflamed gastric mucosa of children.