Characterization of a monoclonal IgMK (IgMGAS) anti-Gd cold agglutinin
(CA). Its coexistence with a monoclonal IgG3K (IgGGAS) without CA activity
that might be clonally related to IgMGAS
MA De la Fuente, C Egile, A Pereira, M Juan, F Vivanco, D Roelcke, G Dighiero and T Gallart
Service of Immunology, Hospital Clinic, Barcelona, Spain.
A monoclonal IgMK (IgMGAS) cold agglutinin (CA) of the infrequent anti- Gd
specificity, found in a patient with Waldenstrom macroglobulinemia, has
been characterized. IgMGAS uses a VH gene homologous (93.7%) to the
reported VH251 germ-line, one of the two functional genes of the VH5
family, with differences in both framework regions and complementary
determining regions (CDR). The VL gene is homologous to the reported 15AVK1
germ-line gene, recently described in an anti-i CA, with differences mostly
clustered in CDR. In the patient's serum, IgMGAS coexisted with a
monoclonal IgG3K (IgGGAS) that lacked CA activity but expressed the private
idiotopes found on IgMGAS. Both Ig lacked reactivity with antibodies
detecting VH1 or VHIII or VKIII subgroup regions or the VH4-21 gene product
that is expressed by anti-I/i CAs. The K chains from both Igs showed the
same isoelectrical mobility. Moreover, the k chains from both serum Igs
showed the same N-terminal amino acid sequence. This sequence was identical
to that predicted by the nucleotide sequence of VK1GAS gene segment,
including one discrepancy at position 15 (Ile for Val) with respect to the
consensus VK1 subgroup regions. Although these data do not exclude a
possible independent clonal origin, they are consistent with the notion
that IgGGAS might be clonally related to IgMGAS.
Volume 83,
Issue 5,
pp. 1310-1322,
03/01/1994
Copyright © 1994 by The American Society of Hematology
