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Lower intratumoral macrophage infiltration seen in solid organ transplant recipients with SCC

Researchers found that although there was no significant difference in tumor-associated macrophage density in tissue samples with squamous cell carcinoma in situ or invasive squamous cell carcinoma from solid organ transplant recipients, there was a significant decrease in intratumoral macrophage infiltration compared with normal tissue samples.

“Despite the association of [tumor-associated macrophage] density and a worse prognosis in most cancers, there was no difference in [tumor-associated macrophage] density between SCC [in situ] and invasive SCC, suggesting that [tumor-associated macrophage] density increases early in cutaneous SCC before tumor invasion beyond the basement membrane and suggesting a role for [tumor-associated macrophages] in the early stages of carcinogenesis,” Nika Cyrus, MD, and colleagues wrote.

Cyrus and colleagues obtained skin tissue samples from 26 solid organ transplant recipients and 19 non-transplant samples, collecting normal skin, SCC and SCC in situ samples. Two slides from each sample were stained with macrophage marker CD68, M1 marker CD40 and M2 marker arginase-1.

The researchers found significantly higher peritumoral and intratumoral macrophage densities in SCC and SCC in situ samples when compared with normal skin samples, regardless of organ transplant status. However, transplant recipients with SCC in situ had significantly lower intratumoral macrophage infiltration when compared with non-transplant patients. The researchers also found that samples of SCC and SCC [in situ] from transplant recipients had more M1 and M2 polarization, and there were significantly lower M2 activation levels for transplant recipients. – by Jeff Craven

Disclosure: The researchers report no relevant financial disclosures.