The ability of human myeloma proteins of different classes and subclasses and of macroglobulins (all aggregated with bis-diazotized benzidine or heat) to aggregate washed human platelets and release [(3)H]-serotonin from the platelets was investigated and compared with the activity of normal IgG and tetanus-antitetanus IgG antigen-antibody complexes. Aggregated IgG1, IgG2, IgG3, IgG4, and norma...

Antibodies of human IgA isotype are critical components of the mucosal immune system, but little is known about their immunotherapeutic potential. Compared with IgG antibodies, IgA molecules carry a C-terminal tail piece extension of 18 amino acids with a free cysteine at position 471. This cysteine is required for the formation of dimeric IgA antibodies, but may impair molecular characteristic...

IgA, the major class of Ig in secretions, classically functions by interfering with microbial attachment to host tissues. Many mucosal pathogens, including Streptococcus pneumoniae, express an IgA1 protease that may circumvent the protective effects of this Ig subclass. Because these proteases are specific for human IgA1, we generated human mAbs to the major surface antigen of the pneumococcus,...

Within T cell–rich areas of secondary lymphoid organs, interdigitating dendritic cells recruit antigen-specific T cells that then induce B cells to secrete Igs. This study investigates the possible role(s) of dendritic cells in the regulation of human B cell responses. In the absence of exogenous cytokines, in vitro generated dendritic cells (referred to as Dendritic Langerhans cells, D-Lc) ind...

Various native and hinge-modified forms of Ig with identical Ids were reacted with an anti-Id mAb, and the resultant immune complexes were analyzed by negative stain immunoelectron microscopy. Complexes were scored for their geometry (linear versus ring complexes) and size (dimer, trimer, etc.). Ring dimers are the thermodynamically most favorable configuration, unless inhibited by steric and/o...

Hairy cell leukemia (HCL) derives from a mature B cell and expresses markers associated with activation. Analysis of immunoglobulin variable region genes has revealed somatic mutation in most cases, consistent with an origin from a cell that has encountered the germinal center. One unusual feature of hairy cells (HCs) is the frequent expression of multiple immunoglobulin heavy chain isotypes, w...

Immunoglobulin A (IgA) is the most abundant antibody isotype in humans and anti-HLA IgA was found sera of transplant recipients. Focusing on patients awaiting kidney re-transplantation, we tested impact anti-HLA-class I/II antibodies graft survival. We analyzed 276 with 238 without allograft failure. Eight motives Fcα receptor (FCAR) Fcγ were The distribution IgA1/A2 IgG differed significantly ...