IgG subclass levels in patients with B cell chronic lymphocytic leukaemia.

Patients with B-cell chronic lymphocytic leukaemia (BCLL) have low levels of serum IgG. In order to determine if this is a pan IgG deficiency or a selective suppression of one or more IgG subclasses, levels of IgG 1, 2, 3 and 4 in nine BCLL patients were determined and compared to those of nine age and sex matched controls. No significant differences were found in the levels of IgG1 and IgG2, but the patients were found to have significantly lower levels of IgG3 (p < 0.05) and IgG4 (p < 0.05). Selective deficiencies of these isotypes may explain the particular pattern of infection seen in BCLL patients.