THE RESPONSE OF PEYER'S PATCH(PP) T CELLS TO COW'S MILK PROTEIN IN CHILDREN

Abstract

75 Background: Our recent studies have demonstrated that children's Peyer's patch (PP) cells but not peripheral blood lymphocytes (PBLs) elicit a vigorous IFN γ response to β-lactoglobulin (β LG) suggesting a local sensitisation in the gut wall in favour of a Th-1 response. Aim: The aim of the present study was to further elucidate this response through use of RT-PCR, proliferation assays and FACS techniques using PP and PB from healthy children. Methods and Results: Following a 24h challenge with β LG or phytohaemagglutinin (PHA), PP cells showed a large increase in IFN γ expression (both p<0.01) as revealed by RT-PCR. There was no significant difference in expression of IL-4 and IL-5 of the β LG-treated PP cells in comparison to the unstimulated control PP cells. In contrast, PBLs failed to show any significant increase in expression of any of the cytokines measured following 24h incubation with β LG. Similarly, β LG failed to significantly increase the proliferation of PBLs cultured for 72h as measured in a standard cell proliferation assays. However, the rate of proliferation of the PP cells incubated with β LG was significantly greater (approximately 8 times). Both PBLs and PP cells cultured in the presence of PHA for 72h elicited strong and similar proliferative responses and increase in number of CD25+cells. Interestingly, PP cells but not PBLs showed a significant increase in CD25+ n cells after 72h culture with β LG. Conclusion: These findings further support the idea that PP cells contain T cells sensitised to cow's milk protein in man which are dominated by Th-1 type responses.