Functional analyses of thymic CD5+ B cells. Responsiveness to major histocompatibility complex class II-restricted T blasts but not to lipopolysaccharide or anti-IgM plus interleukin 4.
The function of thymic B cells in several standard in vitro assays was investigated. Thymic B cells, 75% of which were CD5+, showed a poor responsiveness to the mitogens LPS or anti-mu plus IL-4. Both proliferation and antibody formation were much lower in thymic than splenic B cell cultures. However, CD5- B cells purified using a cell sorter responded well to B cell stimulants, whereas purified CD5+ thymic B cells did not, indicating that CD5+ thymic B cells were unresponsive to B cell growth factor or LPS. Thymic B cells could be activated polyclonally by direct interaction with alloreactive T blasts, as manifested by DNA synthesis and antibody formation. These findings indicate that CD5+ thymic B cells may not be stimulated via sIg and IL-4, but require instead direct interaction with T blasts.
First Department of Pathology, Kansai Medical University, Osaka, Japan.
M
M
Inaba
K
K
Inaba
Y
Y
Adachi
K
K
Nango
H
H
Ogata
S
S
Muramatsu
S
S
Ikehara
D000818:Animals; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000032:analysis*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018956:CD5 Antigens; D002478:Cells, Cultured; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology*; D007700:Kinetics; D008213:Lymphocyte Activation; D051379:Mice; D008809:Mice, Inbred C3H; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D018956:CD5 Antigens; D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M; D015847:Interleukin-4