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In order to elucidate the mechanisms for the elimination of Leishmania, the histological evolution of the lesions of cutaneous leishmaniasis was studied in 118 biopsies from four geographical areas known to be associated with different species or sub-species of Leishmania. Basically there were 3 types of response: A, parasites were eliminated within intact macrophages which later evolved as epithelioid cells; B, they were eliminated as a result of the lysis of the macrophages either individually or in small clusters, but the process was incomplete; C, there was necrosis proceeding to completion at the centre of a focalised mass of macrophages. In B and C the release of parasites caused tissue destruction; epithelioid cells were immature and often sparse, though giant cells were seen in C. A more definite tuberculoid response was found in draining lymph nodes. The response (A, B or C) depended partly on the parasite load, partly on geographical factors. The relative proportions of macrophages, plasma cells and lymphocytes in the lesions varied with the parasite index, but the relationship was the same in all 3 types of response. This suggested that the 3 responses might be the outcome of a common immunological mechanism operating at different antigen levels or antigen-antibody ratios.

Since, however, albumin and globulin values obtained by electrophoresis are likely to become more widely used in clinical work, and since Majoor's method gives results said to be closer to those of electrophoresis than Howe's method, this alone would seem to be a good reason for employing Majoor's. Summary Howe's (using 22% sodium sulphate concentration) and Majoor's (using 26%/ sodium sulphate concentration) methods for differential plasma protein estimation were compared by means of parallel assays on a series of normal and pathological plasnmas.We found that there is little advantage in one method over the other, because the reproducibility of results is identical, the normal ranges are equal, and the separation of results into diagnostic patterns is only slightly better when Majcor's method is used. The arithmetic difference between the two albumin levels is relatively constant in the conditions studied, and therefore either albumin level is reasonably predictable from the other.Since Majoor's method is said to give results closer to those of electrophoresis than Howe's, this, together with the slight advantage indicated by our own results, would seem to be a good reason for employing Majoor's method.

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