Low level of immunoglobulin G2a subclass correlates with a deficiency in T helper cell function in LEC mutant rats.
Long-Evans Cinnamon (LEC) rats bear a congenital deficiency in CD4+8- thymocytes and consequently a deficiency in helper T cell function. This mutation is caused by a single recessive gene referred to as thid (T helper immunodeficiency). It has been reported that rat immunoglobulin(Ig) G2a subclass is a counterpart of the mouse IgG1. Serum IgG2a levels in LEC rats were ten-fold lower than those of normal rats. To identify a cause of low IgG2a levels in LEC rats, we made backcross rats, (F344 x LEC)F1 x LEC, and examined linkage to the thid mutation. The serum IgG2a levels of rats showing thid/thid phenotype were much lower than those of rats showing +/thid phenotype. This indicates that the thid mutation correlates with low level of IgG2a subclass. Furthermore, LEC rat B cells were shown to secret IgG2a normally when these were stimulated with LPS and IL-4, suggesting that a cause of low level of IgG2a was due to defect of T cell function but not due to B cell disfunction in LEC rats. These results confirm the idea that T-helper (Th) function is necessary for the class switch to IgG2a subclass in rats.
Sakai
T
T
Institute for Animal Experimentation, University of Tokushima School of Medicine, Japan.
Agui
T
T
Muramatsu
Y
Y
Nagasawa
H
H
Himeno
K
K
Matsumoto
K
K
D000818:Animals; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D003433:Crosses, Genetic; D004797:Enzyme-Linked Immunosorbent Assay; D005808:Genes, Recessive; D008040:Genetic Linkage; D007074:Immunoglobulin G / Q000097:blood* / Q000145:classification; D007153:Immunologic Deficiency Syndromes / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D010641:Phenotype; D051381:Rats; D011916:Rats, Inbred F344; D011922:Rats, Mutant Strains; D012016:Reference Values; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D016827:CD8 Antigens; D007074:Immunoglobulin G