Isotypy of serum monoclonal immunoglobulins in human immunodeficiency virus-infected adults.

The classes, subclasses and light chain types of 78 serum monoclonal immunoglobulins (MoIg) from adult patients affected with various clinical forms of human immunodeficiency virus (HIV) infection were studied by a sensitive Western blot technique. The incidence of MoIg-containing sera was 26% in a systematic study. Most of these sera contained several (up to eight) detectable MoIg. These MoIg were IgG (91%) and IgM (9%) with a predominance of light chains of the lambda type (kappa:lambda ratio 0.6). The subclass distribution of monoclonal IgG was strikingly different from that observed in myeloma; much less IgG1 and much more IgG3 and IgG4.