SpA-Induced Immunoglobulin Production in Human Peripheral Blood Lymphocytes. : I. Conditions of SpA-Induced Immunoglobulin Production

Abstract

The capacity of soluble Protein A (SpA) to elicite immunoglobulin production of human peripheral blood lymphocytes (PBL) was investigated. Both IgM and IgG class of immunogolbulin (Ig) were produced. Presence of soluble SpA for 2 days in the culture was sufficient for the induction of Ig production of PBL. However, in some subjects, presence of soluble SpA beyond day 2 suppressed Ig production of PBL. Accordingly, in order to obtain optimal responses, cultures were routinely washed on day 2 to remove the free soluble SpA. The magnitude of PFC responses was about one third lower than the Pokeweed mitogen (PWM) induced responses. The magnitude of PFC responses depended upon the concentration of SpA and the highest responses were obtained with concentrations between 10 and 25μg/ml. In the kinetics study, a significant increase in the number of PFC was observed on day 3. The PFC numbers reached a peak on day 5. On the contrary, in PWM-induced responses, the PFC responses reached a peak on day 7. Thus SpA was proved to be have the capacity to induce polyclonal Ig production by PBL as is the case with PWM and to be a useful tool for the study of the mechanisms of human antibody responses.