CD4+ T cell responses in mice lacking MHC class II molecules specifically on B cells.
The role of B lymphocytes in initiating and maintaining a CD4+ T cell response has been examined using a variety of strategies, but remains controversial because of weaknesses inherent to each of the approaches. Here, we address this issue by measuring CD4+ T cell priming both in mutant mice devoid of B cells and in chimeric animals lacking major histocompatibility complex class II molecules specifically on B cells. We find that peptide and some protein antigens do not require B cells expressing class II molecules, nor B cells themselves, to efficiently prime. This could be demonstrated by the usual lymph node proliferation assay, a rather indirect in vitro measure of priming, and by a direct ex vivo assay of population expansion and activation marker expression. Interestingly, one protein antigen, conalbumin, could not prime in the absence of B cells, but could in the presence of B cells devoid of class II molecules. This finding constrains the possible mechanisms whereby B lymphocytes contribute to the initiation of a CD4+ T cell response, arguing against the importance of surface immunoglobulin-mediated antigen presentation by B cells.
Williams
G S
GS
Institut de Génétique et de Biologie Moléculaire et Cellulaire (CNRS/INSERM/ULP), Illkirch, C.U. de Strasbourg, France.
Oxenius
A
A
Hengartner
H
H
Benoist
C
C
Mathis
D
D
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D017578:Immunoglobulin Class Switching; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data
D000949:Histocompatibility Antigens Class II