[Alpha heavy chain disease. Molecular analysis of a new case].

The NH2-terminal structure of serum abnormal protein, as well as the sequence of the corresponding mRNA, were determined in a new case of alpha heavy chain disease. The patient presented with typical clinical features of the disease. Intestinal and mesenteric lymphoplasmic infiltration was monoclonal as assessed by the study of the configuration of heavy and light chain genes.

A human myeloma IgA with a hybrid heavy chain resulting from putative somatic gene conversion.

A human monoclonal IgA1-IgA2 lambda hybrid molecule was detected in a myeloma patient homozygous for the A2m(1) allotype during a systematic study of monoclonal IgA with subclass-specific monoclonal antibodies (mAb) and the lectin jacalin. This monoclonal immunoglobulin (GAU) reacted with both, although not with all, anti-alpha 1 and anti-alpha 2 mAb. Its heavy (H) chain contained an alpha 1 hinge region as shown by jacalin reactivity, the presence of disulfide-linked H and light chains in spite of its belonging to the IgA2m(1) allotype and amino acid composition of the isolated hinge region.

H chain V region sequences of three human monoclonal IgM with anti-myelin-associated glycoprotein activity.

The amino acid sequence corresponding to the V region H chain gene used by three monoclonal IgM directed to the myelin-associated glycoprotein (MAG) is presented. They all belonged to the VHIII variability subgroup, but each may well represent a new member of this family inasmuch as their homology with previously sequenced VHIII genes was less than 80%. Strikingly, there was no greater homology between the H chain V regions of the anti-MAG IgM.

A new extra sequence at the amino terminal of a mu heavy chain disease protein (DAG).

The primary structure of a human mu heavy chain (DAG) protein is described. The native protein is a circular decamer with a molecular weight (Mr) of 500 kDa, each decamer being constituted of the constant domains C mu 2, C mu 3 and C mu4 and interlinked by 15 disulfide bridges. At its NH2-terminal each monomeric chain starts with an "extra sequence".

Peripheral polyneuropathies associated with monoclonal IgM. Antibody activity of monoclonal IgM and therapeutic implications.

Monoclonal IgM from patients with peripheral neuropathy react in nearly 80% of the cases with some components of myelin. The main target is myelin associated glycoprotein (50% of the cases); several types of glycolipids or gangliosides have been identified as the reactive antigen in the other cases. Anti-MAG IgM share little cross reactive idiotopes.