Antibody production in mice. 3. The suppressive effect of antibody on the initiation of secondary immune response

The suppressive effect of antibody on the secondary immune response was analysed using a technique of memory cell transfer into X-irradiated recipients. The response of memory cells stimulated by antigen-bearing cells was markedly suppressed when antibody was passively administered to recipients and this had its maximal effect when administered simultaneously with the cell transfer. The capacity of memory cells to respond to antigenic stimulation and the capacity of antigen-bearing cells to stimulate memory cells were not directly impaired by the suppressive antibody. The marked suppression was observed only when both memory cells and antigen-bearing cells were present together with antibody. These results suggest that antibody-induced suppression appears to be caused by blocking the effective antigenic stimulus from antigen-bearing cells to memory cells.

Evidence is presented indicating that pre-existing antibody plays a regulatory role in the initiation of the secondary response and also controls the expression of memory.

Lung hypoplasia in congenital diaphragmatic hernia. A quantitative study of airway, artery, and alveolar development

From a case of congenital diaphragmatic hernia the pattern of growth of the airways, alveoli, and pulmonary arteries of both lungs, each hypoplastic, has been analysed quantitatively. The impairment of growth for each type of structure is not necessarily the same and differs in each lung. Airway and alveolar numbers are both greatly reduced, although the latter are more nearly normal when related to the number of terminal bronchioli in the lung. In each lung the size of the pulmonary artery at the hilum is appropriate to the lung volume but small for the age of the child. Muscle is found in much smaller arteries than is normal but not to a more peripheral level.

The way the lungs in a case of congenital diaphragmatic hernia might grow after surgical correction of the hernia is discussed and a plea made for respiratory physiological studies in such cases.

Antibody production in mice. II. The mechanism of antigenic stimulation in the secondary immune response

To study the mechanism of antigenic stimulation in the secondary immune response, primed lymphoid cells were stimulated with antigen in various ways in vitro. The effect of antigenic stimulation was assessed by the antibody titres obtained after in vivo culture of primed cells in X-irradiated recipients.

Primed cells were much more effectively stimulated by antigen—antibody (Ag—Ab) complex than by free antigen. Primed cells could also be stimulated by spleen or lymph node cells from normal mice which had been exposed to free antigen or Ag—Ab complex in vitro or in vivo and thoroughly washed. Under these conditions, Ag—Ab complex was again much more effective than free antigen. When the cells were incubated with Ag—Ab complex, the dose of antigen bound to the cells was somewhat increased. But this increased binding of antigen could not solely account for the increase in immunogenicity.

It is suggested that the ingestion of antigen by macrophages is facilitated by the presence of antibody and that the macrophages mediate the effective immune stimulus to memory cells.

The effect of antibody in increasing the immunogenicity of antigen was lost completely when antibody was digested with pepsin. Thus, the Fc portion of antibody seemed to be important for this effect. However, it was demonstrated that antibody does not operate by becoming attached to macrophages as cytophilic antibody, and that complement is not involved in this process. The augmenting mechanism of antibody on the antigenic stimulation mediated by macrophages was discussed.

Antibody production in mice. I. The analysis of immunological memory

The development of immunological memory was analysed by the use of `in vivo culture technique'. The lymphoid cells from primed mice were transferred into heavily irradiated recipients and the size of memory cell population in primed donor mice was estimated quantitatively by the magnitude of secondary responsiveness.

The production of memory cells was detected about 1 week after the primary administration of antigen, and increased gradually up to approximately 6 weeks. The development of the memory cells carrying information for the synthesis of γG₁-antibodies (γG₁-memory cells) was initiated at the early stage of priming and followed by that of the γG₂-memory cells. Although the ratio of population of γG₂- to γG₁-memory cells changed with lapse of time in primed mice, the original ratio of each population in donor, at any stage after priming, was apparently maintained when cultured in recipients for at least 4 weeks. This indicates that the conversion from γG₁- to γG₂-memory cells does not occur.

From these results, it was suggested that the γG₁- and γG₂-memory cells develop independently in primed mice under the continuous stimulation of primarily administered antigen.

Histologic and immunofluorescent studies on the site of origin of glucagon in mammalian pancreas

The present study was designed to investigate the site of origin of glucagon in the adult rabbit pancreas. Tissue fragments, fixed with Carnoy's solution and embedded in paraffin, were sectioned 4 µ in thickness. In a section stained with Gomori's chromium hematoxylin-phloxine, several islets were marked and photographed for comparison with immunofluorescent staining. The same section was then stained by an indirect immunofluorescent method using antiglucagon serum to identify glucagon-containing cells after transfer through xylene, decreasing concentrations of alcohol and buffered saline in succession. The islets previously marked were again observed and photographed under the fluorescent microscope. The specificity of the fluorescent staining was confirmed by the block test, absorption test and others. Good agreement between histologic and immunofluorescent staining of identical sections indicated the α cell origin of glucagon in the rabbit pancreas.