Antigen presentation, antigen-presenting cells and antigen processing.

To summarize, during the period under review there have been considerable advances in our understanding of how antigen is associated with MHC on the surface of a presenting cell. Basic rules which govern this association have been confirmed as including both the nature and the configuration of the antigen. Although the different processing pathways which generate the antigen-MHC complex have remained ill-defined, it is now much more clear what the optimum end point of such processing must be.

Vasitis nodosa and associated clinical findings.

To establish the prevalence of vasitis nodosa in patients who had undergone vasectomy segments of vas deferens resected from 40 patients at the time of vasectomy reversal were examined histologically and immunohistochemically. The findings were correlated with clinical history and postoperative outcome. Controls comprised segments of normal vas deferens excised at vasectomy.

Induction of delayed-type hypersensitivity responses to PPD: dendritic cells in synergy with 5-hydroxytryptamine can substitute for macrophages.

We describe the use of 5-hydroxytryptamine (5HT) as an adjuvant in the induction of the delayed-type hypersensitivity (DTH) response to purified protein derivative (PPD). Based upon our previous studies with antigen-pulsed macrophages (M phi), we have shown that both the Day 2 early (2 hr) reaction and the Day 3 (24 hr) reaction are augmented if 5HT is incorporated into the priming injection. Furthermore, we have confirmed that in contrast to M phi, antigen-pulsed dendritic cells (DC) fail to prime the early (2 hr) component of DTH.

Human T-cell activation: comparative studies on the role of different phorbol esters.

We confirm here previous studies that have shown synergy between anti-CD3 and phorbol esters in the induction of T-cell proliferation. However, for this study we have used tonsillar rather than peripheral blood T cells, and have compared the role of different phorbol esters rather than different anti-CD3 antibodies in the activation process. Three phorbol esters (phorbol myristate acetate, -dibenzoate and -didecanoate) showed a synergistic relationship.

Interaction of lipoproteins with the artery wall.

Atherosclerosis can be defined in terms of the processes involved rather than in morphological terms, and there is evidence for possible roles of the macrophage in atherogenesis. The relevance of hyperlipidaemia to the morphogenesis of the atherosclerotic plaque is important, and this has been described in animal models including a strain of rabbit with a genetically determined hyperlipidaemia resembling familial combined hyperlipidaemia. Treatment of these animals with the HMG CoA reductase inhibitor lovastatin from the time of weaning results in a significant degree of inhibition of lesion formation.

Appendicitis revisited: a comparative study of Malawian and English appendices.

The incidence of appendicitis shows a marked variation between populations which has been attributed to dietary differences. Neural mechanisms and serotonin discharge from subepithelial neurosecretory cells have been previously implicated in pain referable to the appendix and appendicitis. Forty consecutive appendicectomy specimens from Malawi were studied by staining with haematoxylin and eosin, an alcian blue - PAS diastase sequence coupled with lead haematoxylin (PbH) and immunohistology for serotonin and NSE.

The pathology of atherosclerosis with particular reference to the effects of hyperlipidaemia.

A brief description has been given of the major processes involved in the genesis of atherosclerosis, and of the morphological features of fatty streaks, gelatinous elevations and fibrolipid plaques. The effects of hyperlipidaemia, genetically and dietarily determined, are described, with special reference to the possible role of macrophages in the development of arterial lesions caused by such hyperlipidaemias. The administration of a competitive inhibitor of HMG-CoA reductase (lovastatin) to genetically hyperlipidaemic rabbits markedly reduced the extent of intimal surface involvement by lipid-rich lesions.

Dendritic cells from human tissues express receptors for the immunoregulatory vitamin D3 metabolite, dihydroxycholecalciferol.

Dendritic cells have been isolated from human tonsillar tissue and shown to act as accessory cells in a mitogenic response. The dendritic cells will induced receptors for the active metabolite of vitamin D3, 1,25(OH)2D3, in the responder E+ T cells. The dendritic cells themselves constitutively express receptors for the metabolite, and this distinguishes them from other non-T cells in lymphomedullary tissue.

Rationale for the histological spectrum of tuberculosis. A basis for classification.

There is need to re-appraise the cellular response to Mycobacterium tuberculosis. Histological analysis of 54 untreated patients with established disease demonstrated a continuous spectrum of tissue responses in which six groups correlated with evidence of resistance to bacterial multiplication. A predominance of cases in the two middle groups (82%) signified an immunological equilibrium in middle grade resistant patients that is absent in related diseases such as leprosy and cutaneous leishmaniasis.