Distinct expression of perforin and granzyme B in lip and oral cavity squamous cell carcinoma.

BACKGROUND: Perforin and granzyme B (GB) are the main constituents of cytotoxic T-lymphocyte granules, and they have important roles in preventing the initiation and progression of cancer. METHODS: The aim of this study was to compare the expression of CD8(+) /perforin(+) double-staining and GB(+) cells, by immunohistochemistry, in primary oral cavity squamous cell carcinoma (OCSCC), lip squamous cell carcinoma (LSCC), non-dysplastic leukoplakia (LK), dysplastic LK, actinic cheilitis (AC), oral lichen planus (LP) and normal oral mucosa. RESULTS: Our results showed a higher expression of CD8(+) /perforin(+) and GB(+) cells in LSCC when compared with the samples of OCSCC, non-dysplastic and dysplastic LK, AC, oral LP and normal oral mucosa. In addition, increased CD8(+) /perforin(+) and GB(+) cell numbers were observed in all pre-malignant lesions (non-dysplastic LK, dysplastic LK, AC) when compared with the control. CONCLUSIONS: Perforin and GB proteins may contribute to antitumoural immunity, leading to the direct killing of tumour cells; however, it seems to occur more effectively in LSCC than OCSCC.

Natural killer cell dysfunction in patients with systemic-onset juvenile rheumatoid arthritis and macrophage activation syndrome.

OBJECTIVES: To assess natural killer (NK) and cytotoxic functions in patients with systemic-onset juvenile rheumatoid arthrithis (soJRA) complicated by macrophage activation syndrome (MAS). METHODS: NK cells (CD56+/TCRalphabeta-), NK T cells (CD56+/TCRalphabeta+) and CD8+ cells were assessed for perforin expression by flow cytometry. NK cytotoxic activity was measured after coincubation of mononuclear cells with an NK-sensitive K562 cell line. RESULTS: Two major patterns of immunologic abnormalities were detected. Four of 7 patients had decreased NK activity, low NK cell numbers, and mildly increased levels of perforin expression in CD8+ and CD56+ cytotoxic cells. Three remaining patients with MAS, however, had decreased NK activity associated with low levels of perforin expression in all cytotoxic cell populations, a pattern indistinguishable from that in carriers of perforin-deficient familial hemophagocytic lymphohistiocytosis. Remarkably, two of these patients had previous episodes of MAS. CONCLUSIONS: NK dysfunction is an immunologic abnormality common to both familial hemophagocytic lymphohistiocytosis and MAS of soJRA. The extent of NK cell abnormalities in soJRA needs to be further investigated.

Trypanosoma cruzi: resistance to the pore forming protein of cytotoxic lymphocytes--perforin.

The pore-forming protein perforin is one of the main effector molecules which cytotoxic lymphocytes utilize to kill their targets both in vivo and in vitro. Natural killer cells and cytotoxic T lymphocytes play an important role in host defense against a number of intracellular microorganisms such as virus and protozoan, but the exact way they help control infection is unknown. On the other hand, many microorganisms have evolved successful escape strategies to avoid immune-cell-mediated attack. It is thus necessary to investigate the direct interaction of infectious microorganisms with the lytic machinery of cytotoxic lymphocytes and other cells. In the present work we report the effect of perforin on both a protozoan, Trypanosoma cruzi, and the infected host cell. Epimastigote, amastigote, and trypomastigote forms of T. cruzi, as well as infected macrophages, were assayed for their susceptibility to perforin based on three different criteria. T. cruzi in all three differentiation stages were resistant to purified perforin at doses up to 100-fold larger than that sufficient to kill susceptible tumor cells. No morphological change was observed under electron microscopy. Survival rates and infectivities of the treated parasites in vitro were similar to those of control parasites. Moreover, the measurement of calcium influx using Fura-2 to assess membrane damage revealed that T. cruzi resist perforin attack by avoiding transmembrane pore formation. Resistance to perforin was not transferred to host cells since infected macrophages could be easily destroyed by perforin while intracellular amastigotes remained intact.