title: The neonatally thymectomized rat: a model for compensatory IgM antibody formation in exocrine secretions.
abstract: The effect of T-cell deprivation on IgM antibodies in saliva was studied in rats. IgM was never detected in salivas obtained from normal or sham-thymectomized rats, but was detected in saliva samples from 8/15 (53.3%) rats that had undergone neonatal thymectomy. All (6/6) neonatally thymectomized rats exhibited an IgM antibody response to DNP in salivary secretions after local immunization with a T-dependent antigen (DNPBGG), while no IgA anti-DNP activity was detected in saliva from these antimals. IgM antibodies were detected in saliva from 5/7 thymectomized rats following local injection with a T-independent antigen (DNP-Lys-Gicoll). This was accompanied by detectable but substantially reduced levels of secretory IgA antibody in saliva from 7/7 rats. The results suggested that absent or decreased salivary IgA responses accompanying T-cell deprivation in the rats are compensated for by secretion of IgM antibodies into the saliva. The neonatally thymectomized rat may thus provide a model for the study of synthesis, secretion and protective potential of exocrine IgM antibodies.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D004136:Dinitrobenzenes / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D007114:Immunization; D005779:Immunodiffusion; D007071:Immunoglobulin A, Secretory / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis*; D008954:Models, Biological; D051381:Rats; D012463:Saliva / Q000276:immunology*; D013934:Thymectomy
chemical_list: D004136:Dinitrobenzenes; D007071:Immunoglobulin A, Secretory; D007075:Immunoglobulin M