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T cell response to oral immunization with cow's milk proteins in guinea pigs
Abstract
To evaluate the cell-mediated response to oral sensitization, outbred Hartley guinea pigs were fed pasteurized milk (100 ml/day) for a 2-4 week sensitization period. An in vitro proliferation assay was used to examine the antigen-specific responses in sensitized lymphocytes from spleen, mesenteric lymph node and blood. Peripheral blood and mesenteric lymph node lymphocytes were quite responsive whereas splenocytes responded poorly. Peripheral blood lymphocytes from orally sensitized guinea pigs responded significantly (p<0.05) to caseins (cc and 0) and 0-lactoglobulin, and minimally to cc-lactalbumin and whole milk (p>0.05). Even two months after the oral exposure, mesenteric lymph node lymphocytes still proliferated significantly (p<0.05), when cultured with cc and 0 caseins. However, reseeding cow's milk to guinea pigs didn't increase the proliferate response, and may even have induced suppression. Our results suggest that the optimum length of time required for oral sensitization is 2 weeks. Caseins (cc and 0) and 0-lactoglobulin induced a significantly higher proliferate response after 2 weeks of oral sensitization. However, prolonged feeding for 4 weeks with cow's milk downregulated the antigenic response and upregulated the mitogenic response to a polyclonal T cell mitogen (Con A). T cell enrichment prior to culture demonstrated that the increased proliferation in nonenfiched T cell populations was influenced by antigen presenting cells. Using flow cytometric analysis, the study revealed a marked difference in the distribution of phenotypic markers in peripheral blood, spleen, and mesenteric lymph node of guinea pigs fed cow's milk for varying periods of time. Two weeks of oral sensitization yielded more T lymphocytes in spleen, with a predominance of the CD8 subset in the mesenteric lymph node and spleen. On the other hand, 3 weeks of sensitization resulted in fewer CD8+ T cells in the circulation and mesenteric lymph node which, in turn, correlated directly with the ability to enhance the lymphoproliferative reaction. Overall, this study demonstrated for the first time that the oral sensitization with cow's milk can induce antigenic-specific T lymphocyte responses in both local and systemic lymphoid compartments. Caseins (cc and 0) and 0lactoglobulin were found to be the most common sensitizing T cell antigens in orally sensitized guinea pigs. The lymphocyte stimulation assay with highly purified antigens could be useful in the diagnosis of cow's milk allergy in humans.
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Citation
Chitla, Suhasini Reddy (1994). T cell response to oral immunization with cow's milk proteins in guinea pigs. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -C5438.
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