Ontogeny of B-lymphocyte function. II. Ability of endotoxin to increase the heterogeneity of affinity of the immune response of B lymphocytes from fetal mice.

Abstract

We (1) have previously demonstrated that B lymphocytes from neonatal or late fetal mice produced an immune response which was highly restricted with respect to heterogeneity of avidity of the plaque-forming cells (PFC) 1 as compared with the PFC response produced by B lymphocytes from adult donors. These studies were carried out by transferring the lymphoid population to be tested, together with excess adult thymus cells, into lethally irradiated, syngeneic mice. Under these conditions the functional capacity of the B lymphocytes from immature animals could be assayed in an adult environment in the presence of excess adult T lymphocytes. Thus, the restricted heterogeneity of the immune response observed with B lymphocytes from neonatal or 17-day fetal donors could be ascribed to a functional immaturity of the B lymphocyte itself. When evaluated in this system, it was found that B lymphocytes acquire adult functional capabilities between 7 and 10 days of age in LAF1 mice. Our studies described above (1), together with work from a number of other laboratories (2-17), have thus demonstrated an ordered development of various functional and morphological characteristics of the immune system. It was suggested (1) that the temporally abrupt maturation of the competence of B lymphocytes to generate an adult-type, heterogeneous, immune response implied a differentiation event rather than the accumulation of somatic mutations. If this hypothesis were correct, then the B-cell population present in a neonatal animal should have the genetic information required to synthesize the same heterogeneous population of antibody molecules as the adult is capable of producing. This prediction was tested in the present paper by determining whether neonatal or fetal B lymphocytes could be induced, in the transfer system described above, to produce a heterogeneous antibody response if given

Ontogeny of B-lymphocyte function. III. In vivo and in vitro studies on the ease of tolerance induction in B lymphocytes from fetal, neonatal, and adult mice

“…It has been previously shown that cells from 14-or 16-day fetal mice produce mainly IgM PFC. Between day 16 and 17 of fetal life the capacity of B cells to produce indirect PFC develops (10,15). It is also possible that rapid proliferation of this immature B-cell population is at least in part responsible for the failure to induce tolerance.…”

“…The target cells to detect anti-BGG PFC were prepared as described by Golub et al (14) by coupling 24 mg BGG to 0.5 ml washed, packed SRBC in phosphate-buffered saline, pH 6.0, by using 250 mg 1-ethyl-3 (3-dimethylaminopropyl)-carbodiimide HC1 (Sigma Chemical Co.). Anti-DNP PFC were detected by use of picryl coated SRBC as described previously (10,11,15).…”

Immunological studies of aging. II. Loss of IgG and high avidity plaque-forming cells and increased suppressor cell activity in aging mice.

“…The avidity of the indirect anti-DNP PFC was assayed by the inhibition of plaque formation by various concentrations of DNP-EACA according to the method of Andersson (12), as modified by Goidl et al (13). Nine concentrations of DNP-EACA ranging from 1 × 10 -9 to 1 × 10 -5 M in half-log increments were used.…”

“…The Mann-Whitney "U" test has been employed to test significance of difference in PFC numbers between experimental groups. The heterogeneity index is derived from Shannon's formula, as described previously (13).…”

Administration of Adenosine Diphosphate-Ribosyl Transferase Antagonist Allows in vivo Control of Anti-Dinitrophenyl Response

“…An estimate of the range of affinity of anti-DNP antibodies pro duced by immunised control or 3MB-treated mice was obtained by addition of DNP-lysine to the Cunningham chamber, as described elsewhere [10]. Plaque formation around high affinity cells is inhib ited by low concentrations of hapten, while a high concentration of hapten is required for the inhibition of plaque formation around low affinity antibody-secreting cells.…”