Analysis of chicken CD4 by monoclonal antibodies indicates evolutionary conservation between avian and mammalian species.
We have created a panel of mouse monoclonal antibodies detecting different epitopes on avian CD4 molecule. Two-color immunofluorescence analysis shows that chicken peripheral alpha beta T cells are either CD4 or CD8 single positive whereas most gamma delta T cells are CD4-negative both in the thymus and peripheral tissues. Unlabeled antibody competition analysis by flow cytometry demonstrates that several different epitopes on chicken CD4 are recognized by these antibodies. Antibodies precipitate a monomeric glycoprotein from surface-labeled chicken thymocytes and T cells with relative molecular mass (M(r) of 64 kd as analyzed by SDS gel electrophoresis. Removal of N-linked carbohydrates by endoglycosidase-F increases the electrophoretic mobility and reveals the core protein size with M(r) of 45 kd. The anti-CD4 antibodies inhibit antigen-induced cellular proliferation of a keyhole limpet hemocyanin (KLH) -specific T cell line. They synergize in the blocking of T cell proliferation with anti-class II major histocompatibility complex (MHC)-specific antibodies indicating that chicken CD4 is involved in antigen recognition process by CD4+ T cells. We also show that chicken CD4 is down-modulated in a similar manner as its mammalian equivalent when thymocytes are stimulated in vitro with phorbol esters. Altogether these findings suggest functional and biochemical conservation of the CD4 molecule in evolution.
Luhtala
M
M
Department of Medical Microbiology, Turku University, Finland.
Salomonsen
J
J
Hirota
Y
Y
Onodera
T
T
Toivanen
P
P
Vainio
O
O
D000818:Animals; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D015704:CD4 Antigens / Q000737:chemistry / Q000276:immunology*; D002642:Chick Embryo; D002645:Chickens; D015536:Down-Regulation; D000939:Epitopes / Q000032:analysis*; D005434:Flow Cytometry; D008213:Lymphocyte Activation; D011233:Precipitin Tests; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D015704:CD4 Antigens; D000939:Epitopes; D016692:Receptors, Antigen, T-Cell, gamma-delta