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Antigen processing and presentation by small and large B cells
1Department of Biochemistry and Immunology, Federal University of Minas Gerais, Brazil.
We have investigated the ability of different cells from non-immunized mice of the BALB/c strain to present antigen to two ovalbumin-specific I-Ad-restricted T hybridomas. Lipopolysaccharide-activated B-cell blasts were found to be the most efficient antigen-presenting cells. Purified small and dense splenic B cells also stimulated the hybridomas, although not to the same extent as the activated blasts, but comparable to non-fractionated spleen cells. Glutaraldehyde-treated B cells failed to present antigen, whereas F(ab')2 anti-mouse IgM-treated B cells exhibited markedly increased ability to present antigen. Using flow cytometry, we further purified the resting B cells by sorting the small lymphocytes to ensure that the ability of these cells to activate the hybridomas was not due to contamination with large non-resting B cells. The sorted small B cells retained the ability of antigen presentation. Their resting state was confirmed by the fact that they did not incorporate [3H]-thymidine as shown by autoradiographic analysis.
We have investigated the ability of different cells from non-immunized mice of the BALB/c strain to present antigen to two ovalbumin-specific I-Ad-restricted T hybridomas. Lipopolysaccharide-activated B-cell blasts were found to be the most efficient antigen-presenting cells. Purified small and dense splenic B cells also stimulated the hybridomas, although not to the same extent as the activated blasts, but comparable to non-fractionated spleen cells. Glutaraldehyde-treated B cells failed to present antigen, whereas F(ab')2 anti-mouse IgM-treated B cells exhibited markedly increased ability to present antigen. Using flow cytometry, we further purified the resting B cells by sorting the small lymphocytes to ensure that the ability of these cells to activate the hybridomas was not due to contamination with large non-resting B cells. The sorted small B cells retained the ability of antigen presentation. Their resting state was confirmed by the fact that they did not incorporate [3H]-thymidine as shown by autoradiographic analysis.