Specificity of IgM Antibodies to Pooled Human F(ab')₂Fragments

Abstract

An isotope specific immunoassay which minimizes interference by endogenous rheumatoid factors was used to determine the specificity of IgM anti-F(ab')2 antibodies in human serum. We underscore the heterogeneity of these antibodies. While one subset of IgM anti-F(ab')2 antibodies reacts only with intact F(ab')2, another recognizes determinants present following reduction and alkylation of F(ab')2 and separation of Fd' fragments from light chains. IgM anti-F(ab')2 antibodies in sera from rheumatoid arthritis patients do not react significantly with intact pooled IgG and, therefore, probably are not anti-idiotypic antibodies. Some sera, but not all, contain elevated levels of antibodies that are crossreactive with rabbit F(ab')2. Such crossreactive antibodies may interfere with assays which utilize F(ab')2 fragments of rabbit antibodies specific for antigens of clinical relevance.

Molecular orbital conformational energy calculations of the aromatic heterocyclic poly(5,5′‐bibenzoxazole‐2,2′ diyl‐1,4‐phenylene) and poly(2,5‐benzoxazole)

“…In summary, the present calculations indicate preferences for non-planar conformations in AAPBO and for planar conformations in 2,s-ABPBO. These conclusions are consistent with the liquid crystalline behavior observed for 2,5-ABPBO but not for AAPBO (4).…”

“…In fact, PBO and PBT have been t h e focus of t h e U.S. Air Force's "Ordered Polymers" Program aimed at exploiting these characteristics for aerospace applications (1 to 3 ) . More recently, interest has extended to a related group of polymers, poly(5,5'-bibenzoxazole-2,2'-diyl- 1,4-phenylene) (AAPBO) and poly(2,5-benzoxazole) (2, and t o analogues of each containing a sulfur in place of t h e oxygen atom (4…”

The specificity of antibodies to the F(ab′)2 fragment of human IgG

“…This is not to say that JgM anti-E;(ab')* antibodies are less important, but rather that IgM anti-F(ab')* antibodies were not readily purified by our procedures. A report on the specificity of these antibodies in whole serum has been published elsew here (13).…”

Pretransplant serum IgG-anti-F(ab′)2γ activity and kidney graft outcome: comparison of results obtained at two centers

“…It is unknown whether the antigenic sequence recognized by IgG-anti-F(ab')zr is in the constant or variable region of IgG. Evidence exists for both alternatives [6,9]. We believe that anti-immunoglobulin antibodies of different isotypes and different specificities with diverse and even counteracting effects exist.…”