Clonal Nature of the Immune Response to Phosphorylcholine

Abstract

The interaction of antigen with immunoglobulin-like receptors on immunocompetent lymphocytes is considered fundamental to the activation of these committed lymphocytes (1). Using a variety of techniques, independent laboratories have demonstrated the existence of such receptor-bearing cells and their predominantly bone marrow (B)-lymphocyte nature. Selective depletion or enrichment of lymphoid cell function by passage through antigen-coated immunoadsorbents (2-4), by treatment with heavily labeled radioactive antigen (5), or after specific fluorescent labeling and separation in a photoactivated cell sorter (6) has demonstrated indirectly the immunocompetence of these cells. More direct evidence for the presence of lymphocyte receptors has been obtained from autoradiographic studies of specific binding of radioactive antigen to the surface of lymphocytes (4, 7-9). In these studies, the receptors were found to possess heavy-and light-chain determinants (10), and the high degree of hapten specificity (4, 9, 11) classically attributed to circulating antibody. However, neither the immunocompetence of these antigen-binding cells nor their relationship to precursor cells has been proven.A corollary theme and one central to clonal selection theories of antibody formation is that the receptors on a given clone of immunocompetent cells possess essentially the same structural features, at least in the region of the antibody-combining site, as the antibody molecules to be secreted by the descendents of this clone of precursor cells (1). Indirect evidence in support of this hypothesis has been provided by recent studies which have utilized antisera directed to variable region, if not binding site, antigenic determinants. Passive transfer of such specific anti-idiotypic antiserum into unimmunized mice renders them incompetent to produce antibody bearing that idiotype upon immunization (12,13). This suggests the existence, before immunization, of a population of committed lymphocytes with receptors bearing the same idiotypic determinants as circulating antibody.We have pursued directly the relationship between cell surface receptor and secreted antibody molecules in the immune response to phosphorylcholine

Subclass restriction of murine antibodies. II. The IgG plaque-forming cell response to thymus-independent type 1 and type 2 antigens in normal mice and mice expressing an X-linked immunodeficiency.

“…Discussion The TI-2 antigens TNP-FicoI1, dextran, PC-vaccine, and GA-vaccine generate IgG antibody responses predominantly, but not exclusively, of the IgG3 subclass. This fact may explain the difficulty encountered in the past in detecting indirect PFC to these antigens (18,19,22). It is likely that the usual polyspecific facilitating antisera have little activity against the rare subclass IgG3.…”

“…Furthermore, our laboratory has reported the absence of facilitated PFC to PC-vaccine and GAC even though serum IgG antibodies were known to exist (18,19). Thus, it was important to develop efficient methods for detecting IgG PFC to polysaccharides, as well as other determinants.…”

“…Mice in groups of five were immunized with 100 ~g TNP-FicolI, 109 TNP-BA, 100/~g TNP-LPS, 100 #g dextran B1355 (obtained from Dr. M. Slodki, U. S. Department of Agriculture, Peoria, Ill.), or 108 heat-killed Streptococcus pneumoniae strain R36A (PC-vaccine) (18), all in saline intraperitoneally; responses were measured 7 d later. The response to sheep erythrocytes (SRBC) was measured 5 d after the fifth weekly injection of 0.1 ml of 2% washed SRBC intraperitoneally.…”

“…Spleen cells secreting antibody of IgM, IgG1, IgG2 (a+b), and IgG3 subclasses were detected in antigen-specific plaque assay systems with the use of subclassspecific facilitating antisera. SRBC were coated with group A streptococcal carbohydrate (GAC) (19), TNP (20), PC (18), and a(1 ~ 3) dextran (19) by previously described methods. The preparation of rabbit anti-y3 was described previously (10); rabbit anti-y2 and anti-yl were purchased from Gateway Immunosera, Cahokia, Ill. and rendered subclass-specific by solid-phase immunoabsorption.…”

The characterization fo the B-cell repertoire specific for the 2,4-dinitrophenyl and 2,4,6-trinitrophenyl determinants in neonatal BALB/c mice.

“…If a clonotype precursor of one specificity first appears in the fetal spleen (or liver) at day 15 of gestation and subsequently commences a clonal expansion with a B-cell doubling time of 24 h, then by the 2nd day of neonatal life, that clonotype pool size will consist of approximately 200-400 precursor cells, and thus appear as a predominant clonotype. If a second clonotype precursor cell appears somewhat later in gestation (days [16][17], then this second clonotype, after undergoing expansion, would appear predominant at a slightly later time . A process such as this might well explain why the DNP-specific clonotype with a pI of 5.55 appears to be predominant slightly earlier than the DNP-specific clonotype with a pI of 5.25.…”