Marginal Zone and Marginal Sinus Macrophages in the Mouse are Distinct Populations

Abstract

The observations reported here arose from the finding that hapten-conjugated pneumococcal type 3 capsular polysaccharide (S3) is a potent specific inhibitor of anti-hapten antibody responses, especially secondary IgG responses (1). The mechanism involves inactivation of B lymphocytes with receptors for the hapten, and the relevant properties of the conjugate appear to be that sufficient hapten groups are attached to a high molecular weight polymeric carrier which does not itself elicit a thymus dependent response and which is only very slowly degradable in the body (e.g. 2). In a survey of other polysaccharide carriers which might be more readily available than S3 and equally effective after conjugation with haptens at suppressing anti-hapten antibody responses, a variety of neutral and negatively charged polysaccharides were examined. These were directly conjugated with DNP-lysine via CNBr (or via carbodi-imide in the case of pectin and alginic acid) and a small number of tryamine residues were introduced at the same time in order to make it possible to label the conjugates with ¹³¹I or ¹²⁵I for metabolic and autoradiographic studies.