Strain Differences in Production of Direct Plaque‐Forming Cells in Response to DNP‐Ficoll, a Thymus‐Independent Antigen, in Mice

Abstract

2, 4-Dinitrophenyl (DNP) and 2,4,6-trinitrophenyl (TNP) derivatives of Ficoll are well-known thymus-independent antigens which trigger a subset of B cells and cause them to differentiate into antibody-forming cells with the help of macrophages (2). The distinctive characteristics of this response to the thymus-independent antigens in mice are the restriction of the antibody response to IgM and IgG 2 classes (13), the response by ontogenetically late-appearing B cells lacking complement receptors (6) and expressed surface IgD receptors (9), the discovery of X-linked unresponsiveness in an inbred strain of mice (l), and the regulation of antibody production by anti-idiotypic antibodies in vivo (3,12).In the course of analyzing the response of various strains of mice to DNPFicoll, we realized that anti-DNP or anti-TNP plaque-forming cell (PFC) response is strain specific. However, these strain differences were observed only in in vivo experiments; they were not demonstrable in vitro.The C57BL/6Slc (B6) female mice used in this study were obtained from the Shizuoka Agricultural Cooperative for Laboratory Animals, and the C57BL/6J, A/J, SJL/J, and DBA/lJ mice were purchased from Jackson Laboratories. The C3H/HeJ (C3H), C3H/HeMs, (B6 X C3H)Fl, and B6 X F 1 backcross animals were bred in our laboratory.The DNP-Ficoll (36 DNP residues/400,000 molecular weight) and DNP-LPS (lipopolysaccharide extracted from Salmonella typhimurium was obtained from Difco Laboratories) were prepared by the method of Mitchell et al (8). Fluorescein (FITC)-Ficoll (24 residues of FITC/400,000 molecular weight) was prepared by the direct reaction of aminoethyl-carboxymethyl (AECM)-Ficoll with FITC at pH 9.0. PFC assays against sheep red cells (SRBC), DNP-SRBC, TNP-SRBC, and FITC-SRBC were carried out by the method of Jerne and Nordin (4), and the indicator cells for these PFC assays were prepared by the method of Rittenberg and Pratt (11) with the following concentrations of chemically reactive haptens: 50 mM dinitrobenzene sulfonate at pH 9.2, 2 mM trinitrobenzene sulfonate at pH 7.0 and 1 mg of FITC/l0 ml at pH 9.0. Figure 1 shows the direct anti-hapten PFC responses to the thymus-independent antigens including DNP-Ficoll. The mice received either 20 p,g of

Restricted antibody formation to sheep erythrocytes of allogeneic bone marrow chimeras histoincompatible at the K end of the H-2 complex.

“…This observation too fits well with those of our prior report (9) in which the degree of the response to DNP-Ficoll was linked to the donor type of bone marrow ceils and not to the responses of the recipient strain. The quantity of such responses is most likely inheritable, but controlled by non-H-2 and non-Ig heavy chain genes (11). The results presented in Table II also are consonant with our previous findings (9, 11) because allogeneic bone marrow chimeras prepared with bone marrow cells of mice of B10 H-2-congenic lines uniformly showed low responsiveness to DNP-Ficoll.…”

“…None of the cells from the chimeras showed recipient type (Thy-1.1) specificity. quantified by the PFC assay of Jerne described previously (3,(9)(10)(11).…”