Effect of T cell-derived lymphokines containing B cell differentiation factor(s) for IgG (BCDF gamma) on gamma-specific mRNA in murine B cells

Cytoplasmic RNA was isolated from cells cultured with LPS and LPS plus a T cell-derived supernatant (SN) (PK 7.1) containing B cell differentiation factors. The steady state levels of isotype-specific mRNA were assessed by Northern blot analysis with gamma-specific CH3 probes. It was demonstrated that the SN induces an increase in the level of mRNA for gamma 1 and a concomitant decrease in the levels of mRNA for gamma 2b and gamma 3.

Effect of T cell-derived lymphokines containing B cell differentiation factor(s) for IgG (BCDF gamma) on gamma-specific mRNA in murine B cells

Cytoplasmic RNA was isolated from cells cultured with LPS and LPS plus a T cell-derived supernatant (SN) (PK 7.1) containing B cell differentiation factors. The steady state levels of isotype-specific mRNA were assessed by Northern blot analysis with gamma-specific CH3 probes. It was demonstrated that the SN induces an increase in the level of mRNA for gamma 1 and a concomitant decrease in the levels of mRNA for gamma 2b and gamma 3.

Ontogeny of B-lymphocyte function. XIV. Maturation of the capacity of B cells to re-express surface immunoglobulin after treatment with anti-immunoglobulin

The maturation of the ability of the B-cell population to re-express surface immunoglobulin (sIg) after its removal by treatment with rabbit anti-mouse immunoglobulin (RAMIg) was studied in LAF1, C57BL/6, and C57L mice. As demonstrated by previous workers, the B-cell population from immature mice failed to re-express sIg after treatment with RAMIg. We have shown that the age at which the B-cell population acquires the capacity to re-express sIg is different in different strains and that the order in which the B-cell population of the different strains acquires the capacity to re-express sIg is different from the order in which their B-cell populations acquire the capacity to produce high-affinity antibodies. This suggests that these represent distinct differentiation events in the development of the B-cell population. In all of the strains studied the maturation of the capacity to re-express sIg occurred in two steps. After the first maturation step the B-cell population was able to re-express sIg after treatment with RAMIg for 1 hr but did not re-express sIg after treatment with RAMIg for 24 hr. After the second maturation step the B-cell population could re-express sIg even after 24 hr treatment with RAMIg. It has been suggested by previous workers that the inability of the immature B-cell population to re-express sIg could represent one of the mechanisms responsible for the development of B-cell self-tolerance. It is suggested here that the existence of a period during which cells become tolerant only upon prolonged exposure to antigen could protect the developing B cells from becoming unresponsive to transiently experienced foreign antigens but still permit them to become tolerant to self antigens which are continuously present.

Physiology of Igd. II. Lack of humoral immune responsiveness in lymph nodes of mice treated with anti-IgD from birth

Previous studies have shown that anti-IgD-suppressed mice give normal primary and secondary splenic plaque-forming cell responses following i.v. challenge, although mice suppressed by the injection of anti-IgD from birth lack IgD-bearing cells in all lymphoid tissue examined. The present studies show that, in contrast, secondary immune responses in regional lymph nodes of such mice, even after i.v. priming with trinitrophenylated B. abortus, respond to a challenge injection in the footpad up to only less than 10% of control levels. When compared with respect to B cell numbers transferred, primed spleen cells from control and anti-IgD-suppressed mice are about equally effective in producing adoptive secondary plaque-forming cell responses in the spleens of recipient mice. Lymph nodes in recipients of anti-IgD-suppressed primed spleen cells show much lower responses than do lymph nodes in recipients of control primed cells, both upon immediate and delayed challenge with antigen in the footpads. It is concluded that the immunodeficiency caused by suppression with anti-IgD is much more marked in peripheral lymph nodes than in the spleen. The possible relationship of these results to the migratory properties of IgD+ as compared to IgD-B cells is discussed.

Physiology of IgD. I. Compensatory phenomena in B lymphocyte activation in mice treated with anti-IgD antibodies

The role of delta-positive cells in the immune response was studied by comparing the effects of treatment with allotype-specific IgD hybridoma antibody on homozygous BALB/c or SJL/J and heterozygous (BALB x SJL)F1 mice. Homozygous mice, injected from birth with the relevant anti-delta antibody, made primary or secondary immune responses to intravenously injected trinitrophenyl (TNP)-Brucella abortus, TNP-Ficoll, and TNP-keyhole limpet hemocyanin, which did not differ significantly from those of control mice, despite the fact that IgD+ cells were depleted and Ig+ cells were markedly reduced in the spleens of treated mice. Responses in nodes draining a local injection of TNP-Brucella abortus were, however, significantly suppressed. Heterozygous mice, injected from birth with either anti-Ig-5a or anti-Ig-5b, showed a marked reduction in the number cells producing IgG antibody of linked allotype specificity in the secondary response to intravenously injected sheep erythrocytes. A corresponding decrease in the amount of serum IgG2a of that allotype specificity was also noted. However, in agreement with the results obtained in homozygotes, heterozygotes injected simultaneously with anti-IgD directed against each of the allotypes made normal, if not enhanced, plaque-forming cell responses of both allotype specificities. Similarly, serum IgG2a levels were normal in all but one mouse treated in this fashion. These results indicate that IgD+ cells are not essential for an immune response in vivo. Although the delta-positive cell is used preferentially under normal conditions, it appears that an alternative mechanism exists by which, in the absence of these cells, the animal is able to make a normal immune response.