The changes of serum immunoglobulins in patients treated by a combination of anti-CD20 monoclonal antibody rituximab plus chlorambucil for low-grade non- Hodgkin's lymphoma.

PURPOSE: To assess whether the therapeutic application of monoclonal anti-CD20 antibody (rituximab) may affect normal B lymphocyte function, since CD20 is involved in their activation, proliferation and differentiation.

PATIENTS AND

METHODS

Serum immunoglobulins (Igs) concentrations and their possible relation to pretreatment levels of Igs and B-cells ratio as well as the T/B cell ratio were investigated in 9 patients with low-grade non Hodgkin's lymphoma (NHL) during the administration of rituximab (Mabthera(R)) and chlorambucil combination therapy. Serum Igs concentrations were determined by the radial immunodiffusion (RID) method and the number of B and T lymphocytes by flow cytometry analysis.

RESULTS

The altered values of Igs concentration and B cell number were registered in each patient before therapy. Generally, the therapy did not normalize the pretreatment alterations of these parameters, though it depleted malignant clones from peripheral blood. Nevertheless, IgM and IgA concentrations have been considerably changed from baseline level (35-74%) in 5 patients. The concentration of IgA and IgM raised in 4, while the IgM declined from baseline values in 1 patient, irrespective of their therapeutic response. Four of these patients had a normal concentration of these Igs classes, and a profound B cell number alteration before therapy.

CONCLUSION

The changes of IgM and IgA concentrations in relation to pretreatment B cell number, although found in a small number of patients, might deserve further investigation with an aim to study any interference of the anti-CD20-based therapy with lymphocytes function.