The Hb-2d cross-reactive idiotype. A common idiotype expressed by monoclonal and polyclonal antibodies to human haemoglobin.

Hb-2d is a monoclonal antibody of B10.D2 origin that is specific for the beta chain of human adult haemoglobin (HuHb-beta). Polyclonal anti-idiotypic sera to Hb-2d were produced in B10.D2, SJL/J and BALB/c mice. Using anti-idiotypic sera from SJL/J it was observed that Hb-2d expresses a cross-reactive idiotype (CRI) also found on both polyclonal and monoclonal antibodies to HuHb. Polyclonal antisera against HuHb-beta from H-2 congenic mice on the C57BL/10 (B10) background contained antibodies expressing the Hb-2d CRI; these antisera, however, contained little if any antibody to the antigenic determinant on HuHb-beta recognized by Hb-2d. Polyclonal antisera to HuHb-beta from the strains A.CA, A.SW, C3H.OL, BALB/cByJ, DBA/2 and SJL/J contained lower, but nevertheless detectable, amounts of antibody expressing the Hb-2d CRI. Unlike B10-H-2 congenic mice, antisera from the strains A.CA, A.SW and BALB/c bound to the same or a closely associated determinant as that recognized by Hb-2d. Two anti-HuHb monoclonal antibodies, Hb-48a and Hb-53a, both derived from B10-H-2 congenic mice, were shown to possess at least part of the Hb-2d idiotype. These antibodies are specific for epitopes on the human haemoglobin alpha chain (HuHb-alpha). It would appear, therefore, that Hb-2d possesses a CRI that is carried by antibodies to various antigenic determinants on HuHb. The linkage of these different antibodies by the CRI may allow for a common regulatory pathway.