On a mechanism of low level of Ig in a patient with Bence-Jones type myeloma

Abstract

A mechanism of the decrease in polyclonal immunoglobulin (Ig) levels in a patient with multiple myeloma of Bence-Jones type was investigated by measuring Ig synthesis in vitro by mononuclear cells from peripheral blood and bone marrow aspirates. The levels of IgG, A and M in the serum were 579, 37 and 9 mg/dl, respectively. The lymphocytes in the peripheral blood were normal in number and no myeloma cells were found in the Giemsa stained preparation. Ig synthesis by peripheral mononuclear cells was slightly decreased because of the increase in suppressor activity in T cell fraction. Ig synthesis by mononuclear cells from the bone marrow specimen was decreased, approximately to one tenth of the normal controls. Co-culture of the patient's T and B cells with counterpart lymphocytes from a normal donor revealed increase in suppressor activity in T cells in peripheral blood and decrease in bone marrow B cell function in response to T cell stimulation. Considering these results, low levels of Ig in the serum in this patient were considered to be caused mainly by impaired synthesis of Ig in the bone marrow.