beta(2)-microglobulin was detected on the cell surface and in the medium of human lymphoid cells established in long-term culture. The secretion of beta(2)-microglobulin was relatively uniform when different cell lines were compared, whereas IgG production varied widely. kappa- and micro-membrane antigens were modulated by specific antibody; beta(2)-microglobulin was not modulated. Anti-kappa and anti-micro antisera had no effect on the expression of membrane beta(2)-microglobulin, nor had anti-beta(2)-microglobulin antiserum any effect on the expression of kappa- and micro-membrane antigens.