Immunofluorescence analysis of IgA binding by human mononuclear cells in blood and lymphoid tissue.
The nature of IgA-binding cells and their tissue distribution was examined by an indirect immunofluorescence assay with the use of IgA1 and IgA2 paraproteins and fluorochrome- or biotin-labeled F(ab')2 fragments of idiotype-specific antibodies. The frequency of IgA-binding mononuclear cells was approximately 13% in blood and spleen samples but less than 1% in tonsil samples. IgA binding could be visualized by flow immunocytometry on monocyte/macrophages, but not on T and B cells. IgA polymers were bound better than IgA dimers and monomers. Nonhomologous IgA myelomas of both IgA1 and IgA2 subclasses inhibited the IgA-binding to monocytes, whereas aggregated normal serum IgG, IgM paraproteins, and an IgG myeloma did not. IgA binding was relatively insensitive to changes in temperature or cation concentration. IgA-binding monocytes were found in IgA-deficient patients at the same frequency as in normal individuals. The results indicate that monocytes constitutively express class-specific binding sites for both IgA1 and IgA2 molecules.
Chevailler
A
A
Department of Pediatrics, University of Alabama, Birmingham 35294.
Monteiro
R C
RC
Kubagawa
H
H
Cooper
M D
MD
D000361:Agammaglobulinemia / Q000378:metabolism; D000918:Antibody Specificity; D005455:Fluorescent Antibody Technique; D006801:Humans; D017098:IgA Deficiency; D007070:Immunoglobulin A / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008221:Lymphoid Tissue / Q000378:metabolism*; D008222:Lymphokines / Q000032:analysis*; D009000:Monocytes / Q000378:metabolism; D014066:Palatine Tonsil / Q000378:metabolism; D029584:Prostatic Secretory Proteins; D013154:Spleen / Q000378:metabolism
D007070:Immunoglobulin A; D008222:Lymphokines; D029584:Prostatic Secretory Proteins; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors