A human IgA-myeloma protein with anti-streptococcal hyaluronidase (ASH) activity

Retained antigen-binding activity of Fab alpha fragments of human monoclonal immunoglobulin A1 (IgA1) cleaved by IgA1 protease

Immunoglobulin A1 (IgA1) proteases may be important virulence factors of certain bacteria involved in the pathogenesis of meningitis, gonorrhea, destructive periodontal diseases, and some other infections affecting mucosal membranes. This study evaluated the antigen-binding activity of free Fab alpha fragments released from human myeloma IgA1 by IgA1 protease from Haemophilus influenzae. Six myeloma proteins with antibody activity against streptolysin O, alpha-staphylolysin, or streptococcal hyaluronidase were used. Complete cleavage of the IgA1 myeloma proteins in the hinge region of the heavy chain did not affect their antigen-binding capacity. The titers of neutralizing activity associated with free Fab alpha fragments were not significantly different from those of the intact IgA1 proteins. The retained antigen-binding capacity of cleaved IgA1 is an important factor in the understanding of how IgA1 proteases may interfere with the immune protection of mucosal membranes.

Antibodies to common viruses in sera from patients with multiple myeloma

The results of screening for antibodies against rubella, morbilli, mumps, herpes simplex, rota and Epstein-Barr virus in serum from patients with multiple myeloma are reported. Antibodies against herpes simplex virus were found in all samples, present in high titres in most samples. Antibody titres against the other five viruses were generally low. A possible association of common virus infections and myelomatosis is discussed.